Upgrade der to 0.7.8

This project was upgraded with external_updater.
Usage: tools/external_updater/updater.sh update rust/crates/der
For more info, check https://cs.android.com/android/platform/superproject/+/main:tools/external_updater/README.md

Test: TreeHugger
Change-Id: I0a00984745d9de4a1a4c578703e46c6be05334a2

61 files changed, 3278 insertions, 1401 deletions

diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index db1ff23..2f03863 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,6 +1,6 @@
 {
   "git": {
-    "sha1": "14164f9dccd1ba4ceed9938f792b4e99874ef8e0"
+    "sha1": "bb80aa06b3566b0828185e0349e11295ba1aa2f9"
   },
   "path_in_vcs": "der"
 }
\ No newline at end of file
diff --git a/Android.bp b/Android.bp
index 85389e1..31a63ba 100644
--- a/Android.bp
+++ b/Android.bp
@@ -35,13 +35,11 @@ rust_library_host {
     name: "libder",
     crate_name: "der",
     cargo_env_compat: true,
-    cargo_pkg_version: "0.6.1",
+    cargo_pkg_version: "0.7.8",
     srcs: ["src/lib.rs"],
     edition: "2021",
     features: [
         "alloc",
-        "const-oid",
-        "der_derive",
         "derive",
         "flagset",
         "oid",
@@ -59,13 +57,11 @@ rust_library_rlib {
     name: "libder_nostd",
     crate_name: "der",
     cargo_env_compat: true,
-    cargo_pkg_version: "0.6.1",
+    cargo_pkg_version: "0.7.8",
     srcs: ["src/lib.rs"],
     edition: "2021",
     features: [
         "alloc",
-        "const-oid",
-        "der_derive",
         "derive",
         "flagset",
         "oid",
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0472850..0285152 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,124 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## 0.7.8 (2023-08-07)
+### Added
+- `bytes` feature ([#1156])
+- impl `RefToOwned`/`OwnedToRef` for `&[u8]`/`Box<[u8]>` ([#1188])
+- `BmpString` ([#1164])
+
+### Changed
+- no-panic cleanup ([#1169])
+- Bump `der_derive` dependency to v0.7.2 ([#1192])
+
+[#1156]: https://github.com/RustCrypto/formats/pull/1156
+[#1164]: https://github.com/RustCrypto/formats/pull/1164
+[#1169]: https://github.com/RustCrypto/formats/pull/1169
+[#1188]: https://github.com/RustCrypto/formats/pull/1188
+[#1192]: https://github.com/RustCrypto/formats/pull/1192
+
+## 0.7.7 (2023-06-29)
+### Added
+- `TryFrom<String>` impl for strings based on `StrOwned` ([#1064])
+
+[#1064]: https://github.com/RustCrypto/formats/pull/1064
+
+## 0.7.6 (2023-05-16)
+### Added
+- `SetOfVec::{extend, from_iter}` methods ([#1065])
+- `SetOf(Vec)::{insert, insert_ordered}` methods ([#1067])
+
+### Changed
+- Deprecate `SetOf(Vec)::add` ([#1067])
+
+### Fixed
+- Off-by-one error in `BMPString` tag ([#1037])
+- Handling of non-unique items in `SetOf`(Vec) ([#1066])
+
+[#1037]: https://github.com/RustCrypto/formats/pull/1037
+[#1065]: https://github.com/RustCrypto/formats/pull/1065
+[#1066]: https://github.com/RustCrypto/formats/pull/1066
+[#1067]: https://github.com/RustCrypto/formats/pull/1067
+
+## 0.7.5 (2023-04-24)
+### Added
+- adds support for `DateTime::INFINITY` ([#1026])
+
+[#1026]: https://github.com/RustCrypto/formats/pull/1026
+
+## 0.7.4 (2023-04-19)
+### Added
+- `Decode` and `Encode` impls for `PhantomData` ([#1009])
+- `ValueOrd` and `DerOrd` impls for `PhantomData` ([#1012])
+
+### Changed
+- Bump `hex-literal` dependency to v0.4.1 ([#999])
+- Bump `der_derive` dependency to v0.7.1 ([#1016])
+
+[#1009]: https://github.com/RustCrypto/formats/pull/1009
+[#1012]: https://github.com/RustCrypto/formats/pull/1012
+[#1016]: https://github.com/RustCrypto/formats/pull/1016
+
+## 0.7.3 (2023-04-06)
+### Added
+- `UtcTime::MAX_YEAR` associated constant ([#989])
+
+[#989]: https://github.com/RustCrypto/formats/pull/989
+
+## 0.7.2 (2023-04-04)
+### Added
+- Expose `NestedReader ([#925])
+- `From<ObjectIdentifier>` impl for `Any` ([#965])
+- `Any::null` helper ([#969])
+- `Any::encode_from` ([#976])
+
+[#925]: https://github.com/RustCrypto/formats/pull/925
+[#965]: https://github.com/RustCrypto/formats/pull/965
+[#969]: https://github.com/RustCrypto/formats/pull/969
+[#976]: https://github.com/RustCrypto/formats/pull/976
+
+## 0.7.1 (2023-03-07)
+### Changed
+- Make `zeroize`'s `alloc` feature conditional ([#920])
+
+[#920]: https://github.com/RustCrypto/formats/pull/920
+
+## 0.7.0 (2023-02-26) [YANKED]
+### Added
+- `OwnedtoRef`/`RefToOwned` traits; MSRV 1.65 ([#797])
+- `OctetStringRef::decode_into` ([#817])
+- `Int` and `IntRef` types ([#823])
+- `IndefiniteLength` type ([#830])
+- `Any::value` accessor ([#833])
+- Buffered PEM reader ([#839])
+- `OctetString::into_bytes` ([#845])
+- Blanket impls on `Box<T>` for `DecodeValue`, `EncodeValue`, and `Sequence` ([#860])
+
+### Changed
+- Rename `UIntRef` => `UintRef` ([#786])
+- Replace use of `dyn Writer` with `impl Writer` ([#828])
+- Rename `AnyRef::decode_into` -> `::decode_as` ([#829])
+- Bump `pem-rfc7468` dependency to v0.7 ([#894])
+- Rename `Encode::to_vec` => `::to_der` ([#898])
+
+### Removed
+- `Sequence::fields` method ([#828])
+- Inherent `AnyRef` decoding methods ([#829])
+
+[#786]: https://github.com/RustCrypto/formats/pull/786
+[#797]: https://github.com/RustCrypto/formats/pull/797
+[#817]: https://github.com/RustCrypto/formats/pull/817
+[#823]: https://github.com/RustCrypto/formats/pull/823
+[#828]: https://github.com/RustCrypto/formats/pull/828
+[#829]: https://github.com/RustCrypto/formats/pull/829
+[#830]: https://github.com/RustCrypto/formats/pull/830
+[#833]: https://github.com/RustCrypto/formats/pull/833
+[#839]: https://github.com/RustCrypto/formats/pull/839
+[#845]: https://github.com/RustCrypto/formats/pull/845
+[#860]: https://github.com/RustCrypto/formats/pull/860
+[#894]: https://github.com/RustCrypto/formats/pull/894
+[#898]: https://github.com/RustCrypto/formats/pull/898
+
 ## 0.6.1 (2022-12-05)
 ### Added
 - Rudimentary implementation of `TeletexString` and `VideotexString` ([#691])
diff --git a/Cargo.toml b/Cargo.toml
index 1296c9f..a1fcaf1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,9 +11,9 @@
 
 [package]
 edition = "2021"
-rust-version = "1.57"
+rust-version = "1.65"
 name = "der"
-version = "0.6.1"
+version = "0.7.8"
 authors = ["RustCrypto Developers"]
 description = """
 Pure Rust embedded-friendly implementation of the Distinguished Encoding Rules
@@ -44,12 +44,22 @@ rustdoc-args = [
     "docsrs",
 ]
 
+[dependencies.arbitrary]
+version = "1.3"
+features = ["derive"]
+optional = true
+
+[dependencies.bytes]
+version = "1"
+optional = true
+default-features = false
+
 [dependencies.const-oid]
-version = "0.9"
+version = "0.9.2"
 optional = true
 
 [dependencies.der_derive]
-version = "0.6"
+version = "0.7.2"
 optional = true
 
 [dependencies.flagset]
@@ -57,7 +67,8 @@ version = "0.4.3"
 optional = true
 
 [dependencies.pem-rfc7468]
-version = "0.6"
+version = "0.7"
+features = ["alloc"]
 optional = true
 
 [dependencies.time]
@@ -67,23 +78,31 @@ default-features = false
 
 [dependencies.zeroize]
 version = "1.5"
-features = ["alloc"]
 optional = true
 default-features = false
 
 [dev-dependencies.hex-literal]
-version = "0.3.3"
+version = "0.4.1"
 
 [dev-dependencies.proptest]
 version = "1"
 
 [features]
-alloc = []
-derive = ["der_derive"]
-oid = ["const-oid"]
+alloc = ["zeroize?/alloc"]
+arbitrary = [
+    "dep:arbitrary",
+    "const-oid?/arbitrary",
+    "std",
+]
+bytes = [
+    "dep:bytes",
+    "alloc",
+]
+derive = ["dep:der_derive"]
+oid = ["dep:const-oid"]
 pem = [
+    "dep:pem-rfc7468",
     "alloc",
-    "pem-rfc7468/alloc",
     "zeroize",
 ]
 real = []
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
index f8c7dfe..49011a0 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -1,6 +1,6 @@
 [package]
 name = "der"
-version = "0.6.1"
+version = "0.7.8"
 description = """
 Pure Rust embedded-friendly implementation of the Distinguished Encoding Rules
 (DER) for Abstract Syntax Notation One (ASN.1) as described in ITU X.690 with
@@ -13,28 +13,33 @@ categories = ["cryptography", "data-structures", "encoding", "no-std", "parser-i
 keywords = ["asn1", "crypto", "itu", "pkcs"]
 readme = "README.md"
 edition = "2021"
-rust-version = "1.57"
+rust-version = "1.65"
 
 [dependencies]
-const-oid = { version = "0.9", optional = true, path = "../const-oid" }
-der_derive = { version = "0.6", optional = true, path = "derive" }
+arbitrary = { version = "1.3", features = ["derive"], optional = true }
+bytes = { version = "1", optional = true, default-features = false }
+const-oid = { version = "0.9.2", optional = true }
+der_derive = { version = "0.7.2", optional = true }
 flagset = { version = "0.4.3", optional = true }
-pem-rfc7468 = { version = "0.6", optional = true, path = "../pem-rfc7468" }
+pem-rfc7468 = { version = "0.7", optional = true, features = ["alloc"] }
 time = { version = "0.3.4", optional = true, default-features = false }
-zeroize = { version = "1.5", optional = true, default-features = false, features = ["alloc"] }
+zeroize = { version = "1.5", optional = true, default-features = false }
 
 [dev-dependencies]
-hex-literal = "0.3.3"
+hex-literal = "0.4.1"
 proptest = "1"
 
 [features]
-alloc = []
-derive = ["der_derive"]
-oid = ["const-oid"]
-pem = ["alloc", "pem-rfc7468/alloc", "zeroize"]
-real = []
+alloc = ["zeroize?/alloc"]
 std = ["alloc"]
 
+arbitrary = ["dep:arbitrary", "const-oid?/arbitrary", "std"]
+bytes = ["dep:bytes", "alloc"]
+derive = ["dep:der_derive"]
+oid = ["dep:const-oid"]
+pem = ["dep:pem-rfc7468", "alloc", "zeroize"]
+real = []
+
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
diff --git a/LICENSE-MIT b/LICENSE-MIT
index 1b78809..e0d0827 100644
--- a/LICENSE-MIT
+++ b/LICENSE-MIT
@@ -1,4 +1,4 @@
-Copyright (c) 2020-2022 The RustCrypto Project Developers
+Copyright (c) 2020-2023 The RustCrypto Project Developers
 
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated
diff --git a/METADATA b/METADATA
index 3217d88..234bf10 100644
--- a/METADATA
+++ b/METADATA
@@ -1,23 +1,20 @@
 # This project was upgraded with external_updater.
 # Usage: tools/external_updater/updater.sh update rust/crates/der
-# For more info, check https://cs.android.com/android/platform/superproject/+/master:tools/external_updater/README.md
+# For more info, check https://cs.android.com/android/platform/superproject/+/main:tools/external_updater/README.md
 
 name: "der"
 description: "Pure Rust embedded-friendly implementation of the Distinguished Encoding Rules (DER) for Abstract Syntax Notation One (ASN.1) as described in ITU X.690."
 third_party {
-  url {
-    type: HOMEPAGE
-    value: "https://crates.io/crates/der"
-  }
-  url {
-    type: ARCHIVE
-    value: "https://static.crates.io/crates/der/der-0.6.1.crate"
-  }
-  version: "0.6.1"
   license_type: NOTICE
   last_upgrade_date {
-    year: 2022
+    year: 2023
     month: 12
-    day: 9
+    day: 15
+  }
+  homepage: "https://crates.io/crates/der"
+  identifier {
+    type: "Archive"
+    value: "https://static.crates.io/crates/der/der-0.7.8.crate"
+    version: "0.7.8"
   }
 }
diff --git a/README.md b/README.md
index f7bb015..f13053f 100644
--- a/README.md
+++ b/README.md
@@ -49,7 +49,7 @@ encountered. There is currently no way to disable these checks.
 
 ## Minimum Supported Rust Version
 
-This crate requires **Rust 1.57** at a minimum.
+This crate requires **Rust 1.65** at a minimum.
 
 We may change the MSRV in the future, but it will be accompanied by a minor
 version bump.
@@ -78,7 +78,7 @@ dual licensed as above, without any additional terms or conditions.
 [build-image]: https://github.com/RustCrypto/formats/actions/workflows/der.yml/badge.svg
 [build-link]: https://github.com/RustCrypto/formats/actions/workflows/der.yml
 [license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg
-[rustc-image]: https://img.shields.io/badge/rustc-1.57+-blue.svg
+[rustc-image]: https://img.shields.io/badge/rustc-1.65+-blue.svg
 [chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg
 [chat-link]: https://rustcrypto.zulipchat.com/#narrow/stream/300570-formats
 
diff --git a/src/arrayvec.rs b/src/arrayvec.rs
index 21f1341..6ce608d 100644
--- a/src/arrayvec.rs
+++ b/src/arrayvec.rs
@@ -23,14 +23,11 @@ impl<T, const N: usize> ArrayVec<T, N> {
         }
     }
 
-    /// Add an element to this [`ArrayVec`].
-    ///
-    /// Items MUST be added in lexicographical order according to the `Ord`
-    /// impl on `T`.
-    pub fn add(&mut self, element: T) -> Result<()> {
+    /// Push an item into this [`ArrayVec`].
+    pub fn push(&mut self, item: T) -> Result<()> {
         match self.length.checked_add(1) {
             Some(n) if n <= N => {
-                self.elements[self.length] = Some(element);
+                self.elements[self.length] = Some(item);
                 self.length = n;
                 Ok(())
             }
@@ -138,11 +135,11 @@ mod tests {
     #[test]
     fn add() {
         let mut vec = ArrayVec::<u8, 3>::new();
-        vec.add(1).unwrap();
-        vec.add(2).unwrap();
-        vec.add(3).unwrap();
+        vec.push(1).unwrap();
+        vec.push(2).unwrap();
+        vec.push(3).unwrap();
 
-        assert_eq!(vec.add(4).err().unwrap(), ErrorKind::Overlength.into());
+        assert_eq!(vec.push(4).err().unwrap(), ErrorKind::Overlength.into());
         assert_eq!(vec.len(), 3);
     }
 }
diff --git a/src/asn1.rs b/src/asn1.rs
index 34d692b..b04b1b5 100644
--- a/src/asn1.rs
+++ b/src/asn1.rs
@@ -1,8 +1,13 @@
 //! Module containing all of the various ASN.1 built-in types supported by
 //! this library.
 
+#[macro_use]
+mod internal_macros;
+
 mod any;
 mod bit_string;
+#[cfg(feature = "alloc")]
+mod bmp_string;
 mod boolean;
 mod choice;
 mod context_specific;
@@ -32,7 +37,7 @@ pub use self::{
     context_specific::{ContextSpecific, ContextSpecificRef},
     generalized_time::GeneralizedTime,
     ia5_string::Ia5StringRef,
-    integer::bigint::UIntRef,
+    integer::{int::IntRef, uint::UintRef},
     null::Null,
     octet_string::OctetStringRef,
     printable_string::PrintableStringRef,
@@ -46,9 +51,17 @@ pub use self::{
 };
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
-pub use self::{any::Any, bit_string::BitString, octet_string::OctetString, set_of::SetOfVec};
+pub use self::{
+    any::Any,
+    bit_string::BitString,
+    bmp_string::BmpString,
+    ia5_string::Ia5String,
+    integer::{int::Int, uint::Uint},
+    octet_string::OctetString,
+    printable_string::PrintableString,
+    set_of::SetOfVec,
+    teletex_string::TeletexString,
+};
 
 #[cfg(feature = "oid")]
-#[cfg_attr(docsrs, doc(cfg(feature = "oid")))]
 pub use const_oid::ObjectIdentifier;
diff --git a/src/asn1/any.rs b/src/asn1/any.rs
index cb65f23..017a909 100644
--- a/src/asn1/any.rs
+++ b/src/asn1/any.rs
@@ -1,16 +1,15 @@
 //! ASN.1 `ANY` type.
 
+#![cfg_attr(feature = "arbitrary", allow(clippy::integer_arithmetic))]
+
 use crate::{
-    asn1::*, ByteSlice, Choice, Decode, DecodeValue, DerOrd, EncodeValue, Error, ErrorKind,
-    FixedTag, Header, Length, Reader, Result, SliceReader, Tag, Tagged, ValueOrd, Writer,
+    BytesRef, Choice, Decode, DecodeValue, DerOrd, EncodeValue, Error, ErrorKind, Header, Length,
+    Reader, Result, SliceReader, Tag, Tagged, ValueOrd, Writer,
 };
 use core::cmp::Ordering;
 
 #[cfg(feature = "alloc")]
-use alloc::vec::Vec;
-
-#[cfg(feature = "oid")]
-use crate::asn1::ObjectIdentifier;
+use crate::SliceWriter;
 
 /// ASN.1 `ANY`: represents any explicitly tagged ASN.1 value.
 ///
@@ -23,30 +22,31 @@ use crate::asn1::ObjectIdentifier;
 /// Nevertheless, this crate defines an `ANY` type as it remains a familiar
 /// and useful concept which is still extensively used in things like
 /// PKI-related RFCs.
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 pub struct AnyRef<'a> {
     /// Tag representing the type of the encoded value.
     tag: Tag,
 
     /// Inner value encoded as bytes.
-    value: ByteSlice<'a>,
+    value: BytesRef<'a>,
 }
 
 impl<'a> AnyRef<'a> {
     /// [`AnyRef`] representation of the ASN.1 `NULL` type.
     pub const NULL: Self = Self {
         tag: Tag::Null,
-        value: ByteSlice::EMPTY,
+        value: BytesRef::EMPTY,
     };
 
     /// Create a new [`AnyRef`] from the provided [`Tag`] and DER bytes.
     pub fn new(tag: Tag, bytes: &'a [u8]) -> Result<Self> {
-        let value = ByteSlice::new(bytes).map_err(|_| ErrorKind::Length { tag })?;
+        let value = BytesRef::new(bytes).map_err(|_| ErrorKind::Length { tag })?;
         Ok(Self { tag, value })
     }
 
-    /// Infallible creation of an [`AnyRef`] from a [`ByteSlice`].
-    pub(crate) fn from_tag_and_value(tag: Tag, value: ByteSlice<'a>) -> Self {
+    /// Infallible creation of an [`AnyRef`] from a [`BytesRef`].
+    pub(crate) fn from_tag_and_value(tag: Tag, value: BytesRef<'a>) -> Self {
         Self { tag, value }
     }
 
@@ -56,11 +56,14 @@ impl<'a> AnyRef<'a> {
     }
 
     /// Attempt to decode this [`AnyRef`] type into the inner value.
-    pub fn decode_into<T>(self) -> Result<T>
+    pub fn decode_as<T>(self) -> Result<T>
     where
-        T: DecodeValue<'a> + FixedTag,
+        T: Choice<'a> + DecodeValue<'a>,
     {
-        self.tag.assert_eq(T::TAG)?;
+        if !T::can_decode(self.tag) {
+            return Err(self.tag.unexpected_error(None));
+        }
+
         let header = Header {
             tag: self.tag,
             length: self.value.len(),
@@ -76,68 +79,6 @@ impl<'a> AnyRef<'a> {
         self == Self::NULL
     }
 
-    /// Attempt to decode an ASN.1 `BIT STRING`.
-    pub fn bit_string(self) -> Result<BitStringRef<'a>> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `CONTEXT-SPECIFIC` field.
-    pub fn context_specific<T>(self) -> Result<ContextSpecific<T>>
-    where
-        T: Decode<'a>,
-    {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `GeneralizedTime`.
-    pub fn generalized_time(self) -> Result<GeneralizedTime> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `IA5String`.
-    pub fn ia5_string(self) -> Result<Ia5StringRef<'a>> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `OCTET STRING`.
-    pub fn octet_string(self) -> Result<OctetStringRef<'a>> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `OBJECT IDENTIFIER`.
-    #[cfg(feature = "oid")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "oid")))]
-    pub fn oid(self) -> Result<ObjectIdentifier> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `OPTIONAL` value.
-    pub fn optional<T>(self) -> Result<Option<T>>
-    where
-        T: Choice<'a> + TryFrom<Self, Error = Error>,
-    {
-        if T::can_decode(self.tag) {
-            T::try_from(self).map(Some)
-        } else {
-            Ok(None)
-        }
-    }
-
-    /// Attempt to decode an ASN.1 `PrintableString`.
-    pub fn printable_string(self) -> Result<PrintableStringRef<'a>> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `TeletexString`.
-    pub fn teletex_string(self) -> Result<TeletexStringRef<'a>> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `VideotexString`.
-    pub fn videotex_string(self) -> Result<VideotexStringRef<'a>> {
-        self.try_into()
-    }
-
     /// Attempt to decode this value an ASN.1 `SEQUENCE`, creating a new
     /// nested reader and calling the provided argument with it.
     pub fn sequence<F, T>(self, f: F) -> Result<T>
@@ -149,16 +90,6 @@ impl<'a> AnyRef<'a> {
         let result = f(&mut reader)?;
         reader.finish(result)
     }
-
-    /// Attempt to decode an ASN.1 `UTCTime`.
-    pub fn utc_time(self) -> Result<UtcTime> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `UTF8String`.
-    pub fn utf8_string(self) -> Result<Utf8StringRef<'a>> {
-        self.try_into()
-    }
 }
 
 impl<'a> Choice<'a> for AnyRef<'a> {
@@ -170,10 +101,15 @@ impl<'a> Choice<'a> for AnyRef<'a> {
 impl<'a> Decode<'a> for AnyRef<'a> {
     fn decode<R: Reader<'a>>(reader: &mut R) -> Result<AnyRef<'a>> {
         let header = Header::decode(reader)?;
+        Self::decode_value(reader, header)
+    }
+}
 
+impl<'a> DecodeValue<'a> for AnyRef<'a> {
+    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         Ok(Self {
             tag: header.tag,
-            value: ByteSlice::decode_value(reader, header)?,
+            value: BytesRef::decode_value(reader, header)?,
         })
     }
 }
@@ -183,7 +119,7 @@ impl EncodeValue for AnyRef<'_> {
         Ok(self.value.len())
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         writer.write(self.value())
     }
 }
@@ -200,8 +136,8 @@ impl ValueOrd for AnyRef<'_> {
     }
 }
 
-impl<'a> From<AnyRef<'a>> for ByteSlice<'a> {
-    fn from(any: AnyRef<'a>) -> ByteSlice<'a> {
+impl<'a> From<AnyRef<'a>> for BytesRef<'a> {
+    fn from(any: AnyRef<'a>) -> BytesRef<'a> {
         any.value
     }
 }
@@ -214,71 +150,166 @@ impl<'a> TryFrom<&'a [u8]> for AnyRef<'a> {
     }
 }
 
-/// ASN.1 `ANY`: represents any explicitly tagged ASN.1 value.
-///
-/// This type provides the same functionality as [`AnyRef`] but owns the
-/// backing data.
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
-#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
-pub struct Any {
-    /// Tag representing the type of the encoded value.
-    tag: Tag,
-
-    /// Inner value encoded as bytes.
-    value: Vec<u8>,
-}
+pub use self::allocating::Any;
 
 #[cfg(feature = "alloc")]
-impl Any {
-    /// Create a new [`Any`] from the provided [`Tag`] and DER bytes.
-    pub fn new(tag: Tag, bytes: impl Into<Vec<u8>>) -> Result<Self> {
-        let value = bytes.into();
+mod allocating {
+    use super::*;
+    use crate::{referenced::*, BytesOwned};
+    use alloc::boxed::Box;
+
+    /// ASN.1 `ANY`: represents any explicitly tagged ASN.1 value.
+    ///
+    /// This type provides the same functionality as [`AnyRef`] but owns the
+    /// backing data.
+    #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+    #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+    pub struct Any {
+        /// Tag representing the type of the encoded value.
+        tag: Tag,
+
+        /// Inner value encoded as bytes.
+        value: BytesOwned,
+    }
+
+    impl Any {
+        /// Create a new [`Any`] from the provided [`Tag`] and DER bytes.
+        pub fn new(tag: Tag, bytes: impl Into<Box<[u8]>>) -> Result<Self> {
+            let value = BytesOwned::new(bytes)?;
+
+            // Ensure the tag and value are a valid `AnyRef`.
+            AnyRef::new(tag, value.as_slice())?;
+            Ok(Self { tag, value })
+        }
 
-        // Ensure the tag and value are a valid `AnyRef`.
-        AnyRef::new(tag, &value)?;
-        Ok(Self { tag, value })
+        /// Allow access to value
+        pub fn value(&self) -> &[u8] {
+            self.value.as_slice()
+        }
+
+        /// Attempt to decode this [`Any`] type into the inner value.
+        pub fn decode_as<'a, T>(&'a self) -> Result<T>
+        where
+            T: Choice<'a> + DecodeValue<'a>,
+        {
+            AnyRef::from(self).decode_as()
+        }
+
+        /// Encode the provided type as an [`Any`] value.
+        pub fn encode_from<T>(msg: &T) -> Result<Self>
+        where
+            T: Tagged + EncodeValue,
+        {
+            let encoded_len = usize::try_from(msg.value_len()?)?;
+            let mut buf = vec![0u8; encoded_len];
+            let mut writer = SliceWriter::new(&mut buf);
+            msg.encode_value(&mut writer)?;
+            writer.finish()?;
+            Any::new(msg.tag(), buf)
+        }
+
+        /// Attempt to decode this value an ASN.1 `SEQUENCE`, creating a new
+        /// nested reader and calling the provided argument with it.
+        pub fn sequence<'a, F, T>(&'a self, f: F) -> Result<T>
+        where
+            F: FnOnce(&mut SliceReader<'a>) -> Result<T>,
+        {
+            AnyRef::from(self).sequence(f)
+        }
+
+        /// [`Any`] representation of the ASN.1 `NULL` type.
+        pub fn null() -> Self {
+            Self {
+                tag: Tag::Null,
+                value: BytesOwned::default(),
+            }
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl Choice<'_> for Any {
-    fn can_decode(_: Tag) -> bool {
-        true
+    impl Choice<'_> for Any {
+        fn can_decode(_: Tag) -> bool {
+            true
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl<'a> Decode<'a> for Any {
-    fn decode<R: Reader<'a>>(reader: &mut R) -> Result<Self> {
-        let header = Header::decode(reader)?;
-        let value = reader.read_vec(header.length)?;
-        Self::new(header.tag, value)
+    impl<'a> Decode<'a> for Any {
+        fn decode<R: Reader<'a>>(reader: &mut R) -> Result<Self> {
+            let header = Header::decode(reader)?;
+            Self::decode_value(reader, header)
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl EncodeValue for Any {
-    fn value_len(&self) -> Result<Length> {
-        self.value.len().try_into()
+    impl<'a> DecodeValue<'a> for Any {
+        fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+            let value = reader.read_vec(header.length)?;
+            Self::new(header.tag, value)
+        }
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        writer.write(&self.value)
+    impl EncodeValue for Any {
+        fn value_len(&self) -> Result<Length> {
+            Ok(self.value.len())
+        }
+
+        fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+            writer.write(self.value.as_slice())
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl<'a> From<&'a Any> for AnyRef<'a> {
-    fn from(any: &'a Any) -> AnyRef<'a> {
-        // Ensured to parse successfully in constructor
-        AnyRef::new(any.tag, &any.value).expect("invalid ANY")
+    impl<'a> From<&'a Any> for AnyRef<'a> {
+        fn from(any: &'a Any) -> AnyRef<'a> {
+            // Ensured to parse successfully in constructor
+            AnyRef::new(any.tag, any.value.as_slice()).expect("invalid ANY")
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl Tagged for Any {
-    fn tag(&self) -> Tag {
-        self.tag
+    impl Tagged for Any {
+        fn tag(&self) -> Tag {
+            self.tag
+        }
+    }
+
+    impl ValueOrd for Any {
+        fn value_cmp(&self, other: &Self) -> Result<Ordering> {
+            self.value.der_cmp(&other.value)
+        }
+    }
+
+    impl<'a, T> From<T> for Any
+    where
+        T: Into<AnyRef<'a>>,
+    {
+        fn from(input: T) -> Any {
+            let anyref: AnyRef<'a> = input.into();
+            Self {
+                tag: anyref.tag(),
+                value: BytesOwned::from(anyref.value),
+            }
+        }
+    }
+
+    impl<'a> RefToOwned<'a> for AnyRef<'a> {
+        type Owned = Any;
+        fn ref_to_owned(&self) -> Self::Owned {
+            Any {
+                tag: self.tag(),
+                value: BytesOwned::from(self.value),
+            }
+        }
+    }
+
+    impl OwnedToRef for Any {
+        type Borrowed<'a> = AnyRef<'a>;
+        fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+            self.into()
+        }
+    }
+
+    impl Any {
+        /// Is this value an ASN.1 `NULL` value?
+        pub fn is_null(&self) -> bool {
+            self.owned_to_ref() == AnyRef::NULL
+        }
     }
 }
diff --git a/src/asn1/bit_string.rs b/src/asn1/bit_string.rs
index eed14e4..bf3371c 100644
--- a/src/asn1/bit_string.rs
+++ b/src/asn1/bit_string.rs
@@ -1,14 +1,11 @@
 //! ASN.1 `BIT STRING` support.
 
 use crate::{
-    asn1::AnyRef, ByteSlice, DecodeValue, DerOrd, EncodeValue, Error, ErrorKind, FixedTag, Header,
-    Length, Reader, Result, Tag, ValueOrd, Writer,
+    BytesRef, DecodeValue, DerOrd, EncodeValue, Error, ErrorKind, FixedTag, Header, Length, Reader,
+    Result, Tag, ValueOrd, Writer,
 };
 use core::{cmp::Ordering, iter::FusedIterator};
 
-#[cfg(feature = "alloc")]
-use alloc::vec::Vec;
-
 /// ASN.1 `BIT STRING` type.
 ///
 /// This type contains a sequence of any number of bits, modeled internally as
@@ -24,7 +21,7 @@ pub struct BitStringRef<'a> {
     bit_length: usize,
 
     /// Bitstring represented as a slice of bytes.
-    inner: ByteSlice<'a>,
+    inner: BytesRef<'a>,
 }
 
 impl<'a> BitStringRef<'a> {
@@ -40,7 +37,7 @@ impl<'a> BitStringRef<'a> {
             return Err(Self::TAG.value_error());
         }
 
-        let inner = ByteSlice::new(bytes).map_err(|_| Self::TAG.length_error())?;
+        let inner = BytesRef::new(bytes).map_err(|_| Self::TAG.length_error())?;
 
         let bit_length = usize::try_from(inner.len())?
             .checked_mul(8)
@@ -120,6 +117,8 @@ impl<'a> BitStringRef<'a> {
     }
 }
 
+impl_any_conversions!(BitStringRef<'a>, 'a);
+
 impl<'a> DecodeValue<'a> for BitStringRef<'a> {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         let header = Header {
@@ -128,7 +127,7 @@ impl<'a> DecodeValue<'a> for BitStringRef<'a> {
         };
 
         let unused_bits = reader.read_byte()?;
-        let inner = ByteSlice::decode_value(reader, header)?;
+        let inner = BytesRef::decode_value(reader, header)?;
         Self::new(unused_bits, inner.as_slice())
     }
 }
@@ -138,7 +137,7 @@ impl EncodeValue for BitStringRef<'_> {
         self.byte_len() + Length::ONE
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         writer.write_byte(self.unused_bits)?;
         writer.write(self.raw_bytes())
     }
@@ -159,14 +158,6 @@ impl<'a> From<&BitStringRef<'a>> for BitStringRef<'a> {
     }
 }
 
-impl<'a> TryFrom<AnyRef<'a>> for BitStringRef<'a> {
-    type Error = Error;
-
-    fn try_from(any: AnyRef<'a>) -> Result<BitStringRef<'a>> {
-        any.decode_into()
-    }
-}
-
 impl<'a> TryFrom<&'a [u8]> for BitStringRef<'a> {
     type Error = Error;
 
@@ -180,7 +171,7 @@ impl<'a> TryFrom<&&'a [u8]> for BitStringRef<'a> {
     type Error = Error;
 
     fn try_from(bytes: &&'a [u8]) -> Result<BitStringRef<'a>> {
-        BitStringRef::from_bytes(*bytes)
+        BitStringRef::from_bytes(bytes)
     }
 }
 
@@ -198,141 +189,198 @@ impl<'a> FixedTag for BitStringRef<'a> {
     const TAG: Tag = Tag::BitString;
 }
 
-/// Owned form of ASN.1 `BIT STRING` type.
-///
-/// This type provides the same functionality as [`BitStringRef`] but owns the
-/// backing data.
-#[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
-#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
-pub struct BitString {
-    /// Number of unused bits in the final octet.
-    unused_bits: u8,
-
-    /// Length of this `BIT STRING` in bits.
-    bit_length: usize,
+// Implement by hand because the derive would create invalid values.
+// Use the constructor to create a valid value.
+#[cfg(feature = "arbitrary")]
+impl<'a> arbitrary::Arbitrary<'a> for BitStringRef<'a> {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        Self::new(
+            u.int_in_range(0..=Self::MAX_UNUSED_BITS)?,
+            BytesRef::arbitrary(u)?.as_slice(),
+        )
+        .map_err(|_| arbitrary::Error::IncorrectFormat)
+    }
 
-    /// Bitstring represented as a slice of bytes.
-    inner: Vec<u8>,
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        arbitrary::size_hint::and(u8::size_hint(depth), BytesRef::size_hint(depth))
+    }
 }
 
 #[cfg(feature = "alloc")]
-impl BitString {
-    /// Maximum number of unused bits allowed.
-    pub const MAX_UNUSED_BITS: u8 = 7;
+pub use self::allocating::BitString;
 
-    /// Create a new ASN.1 `BIT STRING` from a byte slice.
+#[cfg(feature = "alloc")]
+mod allocating {
+    use super::*;
+    use crate::referenced::*;
+    use alloc::vec::Vec;
+
+    /// Owned form of ASN.1 `BIT STRING` type.
     ///
-    /// Accepts an optional number of "unused bits" (0-7) which are omitted
-    /// from the final octet. This number is 0 if the value is octet-aligned.
-    pub fn new(unused_bits: u8, bytes: impl Into<Vec<u8>>) -> Result<Self> {
-        let inner = bytes.into();
+    /// This type provides the same functionality as [`BitStringRef`] but owns the
+    /// backing data.
+    #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+    pub struct BitString {
+        /// Number of unused bits in the final octet.
+        unused_bits: u8,
+
+        /// Length of this `BIT STRING` in bits.
+        bit_length: usize,
+
+        /// Bitstring represented as a slice of bytes.
+        inner: Vec<u8>,
+    }
+
+    impl BitString {
+        /// Maximum number of unused bits allowed.
+        pub const MAX_UNUSED_BITS: u8 = 7;
+
+        /// Create a new ASN.1 `BIT STRING` from a byte slice.
+        ///
+        /// Accepts an optional number of "unused bits" (0-7) which are omitted
+        /// from the final octet. This number is 0 if the value is octet-aligned.
+        pub fn new(unused_bits: u8, bytes: impl Into<Vec<u8>>) -> Result<Self> {
+            let inner = bytes.into();
+
+            // Ensure parameters parse successfully as a `BitStringRef`.
+            let bit_length = BitStringRef::new(unused_bits, &inner)?.bit_length;
+
+            Ok(BitString {
+                unused_bits,
+                bit_length,
+                inner,
+            })
+        }
 
-        // Ensure parameters parse successfully as a `BitStringRef`.
-        let bit_length = BitStringRef::new(unused_bits, &inner)?.bit_length;
+        /// Create a new ASN.1 `BIT STRING` from the given bytes.
+        ///
+        /// The "unused bits" are set to 0.
+        pub fn from_bytes(bytes: &[u8]) -> Result<Self> {
+            Self::new(0, bytes)
+        }
 
-        Ok(BitString {
-            unused_bits,
-            bit_length,
-            inner,
-        })
-    }
+        /// Get the number of unused bits in the octet serialization of this
+        /// `BIT STRING`.
+        pub fn unused_bits(&self) -> u8 {
+            self.unused_bits
+        }
 
-    /// Create a new ASN.1 `BIT STRING` from the given bytes.
-    ///
-    /// The "unused bits" are set to 0.
-    pub fn from_bytes(bytes: &[u8]) -> Result<Self> {
-        Self::new(0, bytes)
-    }
+        /// Is the number of unused bits a value other than 0?
+        pub fn has_unused_bits(&self) -> bool {
+            self.unused_bits != 0
+        }
 
-    /// Get the number of unused bits in the octet serialization of this
-    /// `BIT STRING`.
-    pub fn unused_bits(&self) -> u8 {
-        self.unused_bits
-    }
+        /// Get the length of this `BIT STRING` in bits.
+        pub fn bit_len(&self) -> usize {
+            self.bit_length
+        }
 
-    /// Is the number of unused bits a value other than 0?
-    pub fn has_unused_bits(&self) -> bool {
-        self.unused_bits != 0
-    }
+        /// Is the inner byte slice empty?
+        pub fn is_empty(&self) -> bool {
+            self.inner.is_empty()
+        }
 
-    /// Get the length of this `BIT STRING` in bits.
-    pub fn bit_len(&self) -> usize {
-        self.bit_length
-    }
+        /// Borrow the inner byte slice.
+        ///
+        /// Returns `None` if the number of unused bits is *not* equal to zero,
+        /// i.e. if the `BIT STRING` is not octet aligned.
+        ///
+        /// Use [`BitString::raw_bytes`] to obtain access to the raw value
+        /// regardless of the presence of unused bits.
+        pub fn as_bytes(&self) -> Option<&[u8]> {
+            if self.has_unused_bits() {
+                None
+            } else {
+                Some(self.raw_bytes())
+            }
+        }
 
-    /// Is the inner byte slice empty?
-    pub fn is_empty(&self) -> bool {
-        self.inner.is_empty()
-    }
+        /// Borrow the raw bytes of this `BIT STRING`.
+        pub fn raw_bytes(&self) -> &[u8] {
+            self.inner.as_slice()
+        }
 
-    /// Borrow the inner byte slice.
-    ///
-    /// Returns `None` if the number of unused bits is *not* equal to zero,
-    /// i.e. if the `BIT STRING` is not octet aligned.
-    ///
-    /// Use [`BitString::raw_bytes`] to obtain access to the raw value
-    /// regardless of the presence of unused bits.
-    pub fn as_bytes(&self) -> Option<&[u8]> {
-        if self.has_unused_bits() {
-            None
-        } else {
-            Some(self.raw_bytes())
+        /// Iterator over the bits of this `BIT STRING`.
+        pub fn bits(&self) -> BitStringIter<'_> {
+            BitStringRef::from(self).bits()
         }
     }
 
-    /// Borrow the raw bytes of this `BIT STRING`.
-    pub fn raw_bytes(&self) -> &[u8] {
-        self.inner.as_slice()
+    impl_any_conversions!(BitString);
+
+    impl<'a> DecodeValue<'a> for BitString {
+        fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+            let inner_len = (header.length - Length::ONE)?;
+            let unused_bits = reader.read_byte()?;
+            let inner = reader.read_vec(inner_len)?;
+            Self::new(unused_bits, inner)
+        }
     }
 
-    /// Iterator over the bits of this `BIT STRING`.
-    pub fn bits(&self) -> BitStringIter<'_> {
-        BitStringRef::from(self).bits()
+    impl EncodeValue for BitString {
+        fn value_len(&self) -> Result<Length> {
+            Length::ONE + Length::try_from(self.inner.len())?
+        }
+
+        fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+            writer.write_byte(self.unused_bits)?;
+            writer.write(&self.inner)
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl<'a> DecodeValue<'a> for BitString {
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        let inner_len = (header.length - Length::ONE)?;
-        let unused_bits = reader.read_byte()?;
-        let inner = reader.read_vec(inner_len)?;
-        Self::new(unused_bits, inner)
+    impl FixedTag for BitString {
+        const TAG: Tag = Tag::BitString;
     }
-}
 
-#[cfg(feature = "alloc")]
-impl EncodeValue for BitString {
-    fn value_len(&self) -> Result<Length> {
-        Length::ONE + Length::try_from(self.inner.len())?
+    impl<'a> From<&'a BitString> for BitStringRef<'a> {
+        fn from(bit_string: &'a BitString) -> BitStringRef<'a> {
+            // Ensured to parse successfully in constructor
+            BitStringRef::new(bit_string.unused_bits, &bit_string.inner)
+                .expect("invalid BIT STRING")
+        }
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        writer.write_byte(self.unused_bits)?;
-        writer.write(&self.inner)
+    impl ValueOrd for BitString {
+        fn value_cmp(&self, other: &Self) -> Result<Ordering> {
+            match self.unused_bits.cmp(&other.unused_bits) {
+                Ordering::Equal => self.inner.der_cmp(&other.inner),
+                ordering => Ok(ordering),
+            }
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl FixedTag for BitString {
-    const TAG: Tag = Tag::BitString;
-}
+    // Implement by hand because the derive would create invalid values.
+    // Use the constructor to create a valid value.
+    #[cfg(feature = "arbitrary")]
+    impl<'a> arbitrary::Arbitrary<'a> for BitString {
+        fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+            Self::new(
+                u.int_in_range(0..=Self::MAX_UNUSED_BITS)?,
+                BytesRef::arbitrary(u)?.as_slice(),
+            )
+            .map_err(|_| arbitrary::Error::IncorrectFormat)
+        }
 
-#[cfg(feature = "alloc")]
-impl<'a> From<&'a BitString> for BitStringRef<'a> {
-    fn from(bit_string: &'a BitString) -> BitStringRef<'a> {
-        // Ensured to parse successfully in constructor
-        BitStringRef::new(bit_string.unused_bits, &bit_string.inner).expect("invalid BIT STRING")
+        fn size_hint(depth: usize) -> (usize, Option<usize>) {
+            arbitrary::size_hint::and(u8::size_hint(depth), BytesRef::size_hint(depth))
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl ValueOrd for BitString {
-    fn value_cmp(&self, other: &Self) -> Result<Ordering> {
-        match self.unused_bits.cmp(&other.unused_bits) {
-            Ordering::Equal => self.inner.der_cmp(&other.inner),
-            ordering => Ok(ordering),
+    impl<'a> RefToOwned<'a> for BitStringRef<'a> {
+        type Owned = BitString;
+        fn ref_to_owned(&self) -> Self::Owned {
+            BitString {
+                unused_bits: self.unused_bits,
+                bit_length: self.bit_length,
+                inner: Vec::from(self.inner.as_slice()),
+            }
+        }
+    }
+
+    impl OwnedToRef for BitString {
+        type Borrowed<'a> = BitStringRef<'a>;
+        fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+            self.into()
         }
     }
 }
@@ -445,7 +493,7 @@ where
         BitStringRef::new((lead % 8) as u8, buff)?.value_len()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         let (lead, buff) = encode_flagset(self);
         let buff = &buff[..buff.len() - lead / 8];
         BitStringRef::new((lead % 8) as u8, buff)?.encode_value(writer)
@@ -486,7 +534,7 @@ mod tests {
         assert_eq!(bits.len(), 18);
 
         for bit in [0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1] {
-            assert_eq!(bits.next().unwrap() as u8, bit)
+            assert_eq!(u8::from(bits.next().unwrap()), bit)
         }
 
         // Ensure `None` is returned on successive calls
diff --git a/src/asn1/bmp_string.rs b/src/asn1/bmp_string.rs
new file mode 100644
index 0000000..b4135d5
--- /dev/null
+++ b/src/asn1/bmp_string.rs
@@ -0,0 +1,164 @@
+//! ASN.1 `BMPString` support.
+
+use crate::{
+    BytesOwned, DecodeValue, EncodeValue, Error, FixedTag, Header, Length, Reader, Result, Tag,
+    Writer,
+};
+use alloc::{boxed::Box, vec::Vec};
+use core::{fmt, str::FromStr};
+
+/// ASN.1 `BMPString` type.
+///
+/// Encodes Basic Multilingual Plane (BMP) subset of Unicode (ISO 10646),
+/// a.k.a. UCS-2.
+#[derive(Clone, Eq, PartialEq, PartialOrd, Ord)]
+pub struct BmpString {
+    bytes: BytesOwned,
+}
+
+impl BmpString {
+    /// Create a new [`BmpString`] from its UCS-2 encoding.
+    pub fn from_ucs2(bytes: impl Into<Box<[u8]>>) -> Result<Self> {
+        let bytes = bytes.into();
+
+        if bytes.len() % 2 != 0 {
+            return Err(Tag::BmpString.length_error());
+        }
+
+        let ret = Self {
+            bytes: bytes.try_into()?,
+        };
+
+        for maybe_char in char::decode_utf16(ret.codepoints()) {
+            match maybe_char {
+                // All surrogates paired and character is in the Basic Multilingual Plane
+                Ok(c) if (c as u64) < u64::from(u16::MAX) => (),
+                // Unpaired surrogates or characters outside Basic Multilingual Plane
+                _ => return Err(Tag::BmpString.value_error()),
+            }
+        }
+
+        Ok(ret)
+    }
+
+    /// Create a new [`BmpString`] from a UTF-8 string.
+    pub fn from_utf8(utf8: &str) -> Result<Self> {
+        let capacity = utf8
+            .len()
+            .checked_mul(2)
+            .ok_or_else(|| Tag::BmpString.length_error())?;
+
+        let mut bytes = Vec::with_capacity(capacity);
+
+        for code_point in utf8.encode_utf16() {
+            bytes.extend(code_point.to_be_bytes());
+        }
+
+        Self::from_ucs2(bytes)
+    }
+
+    /// Borrow the encoded UCS-2 as bytes.
+    pub fn as_bytes(&self) -> &[u8] {
+        self.bytes.as_ref()
+    }
+
+    /// Obtain the inner bytes.
+    #[inline]
+    pub fn into_bytes(self) -> Box<[u8]> {
+        self.bytes.into()
+    }
+
+    /// Get an iterator over characters in the string.
+    pub fn chars(&self) -> impl Iterator<Item = char> + '_ {
+        char::decode_utf16(self.codepoints())
+            .map(|maybe_char| maybe_char.expect("unpaired surrogates checked in constructor"))
+    }
+
+    /// Get an iterator over the `u16` codepoints.
+    pub fn codepoints(&self) -> impl Iterator<Item = u16> + '_ {
+        // TODO(tarcieri): use `array_chunks`
+        self.as_bytes()
+            .chunks_exact(2)
+            .map(|chunk| u16::from_be_bytes([chunk[0], chunk[1]]))
+    }
+}
+
+impl AsRef<[u8]> for BmpString {
+    fn as_ref(&self) -> &[u8] {
+        self.as_bytes()
+    }
+}
+
+impl<'a> DecodeValue<'a> for BmpString {
+    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+        Self::from_ucs2(reader.read_vec(header.length)?)
+    }
+}
+
+impl EncodeValue for BmpString {
+    fn value_len(&self) -> Result<Length> {
+        Ok(self.bytes.len())
+    }
+
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+        writer.write(self.as_bytes())
+    }
+}
+
+impl FixedTag for BmpString {
+    const TAG: Tag = Tag::BmpString;
+}
+
+impl FromStr for BmpString {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        Self::from_utf8(s)
+    }
+}
+
+impl fmt::Debug for BmpString {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "BmpString(\"{}\")", self)
+    }
+}
+
+impl fmt::Display for BmpString {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for c in self.chars() {
+            write!(f, "{}", c)?;
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::BmpString;
+    use crate::{Decode, Encode};
+    use alloc::string::ToString;
+    use hex_literal::hex;
+
+    const EXAMPLE_BYTES: &[u8] = &hex!(
+        "1e 26 00 43 00 65 00 72 00 74"
+        "      00 69 00 66 00 69 00 63"
+        "      00 61 00 74 00 65 00 54"
+        "      00 65 00 6d 00 70 00 6c"
+        "      00 61 00 74 00 65"
+    );
+
+    const EXAMPLE_UTF8: &str = "CertificateTemplate";
+
+    #[test]
+    fn decode() {
+        let bmp_string = BmpString::from_der(EXAMPLE_BYTES).unwrap();
+        assert_eq!(bmp_string.to_string(), EXAMPLE_UTF8);
+    }
+
+    #[test]
+    fn encode() {
+        let bmp_string = BmpString::from_utf8(EXAMPLE_UTF8).unwrap();
+        let encoded = bmp_string.to_der().unwrap();
+        assert_eq!(encoded, EXAMPLE_BYTES);
+    }
+}
diff --git a/src/asn1/boolean.rs b/src/asn1/boolean.rs
index e032181..3eb0f2e 100644
--- a/src/asn1/boolean.rs
+++ b/src/asn1/boolean.rs
@@ -1,8 +1,8 @@
 //! ASN.1 `BOOLEAN` support.
 
 use crate::{
-    asn1::AnyRef, ord::OrdIsValueOrd, ByteSlice, DecodeValue, EncodeValue, Error, ErrorKind,
-    FixedTag, Header, Length, Reader, Result, Tag, Writer,
+    asn1::AnyRef, ord::OrdIsValueOrd, DecodeValue, EncodeValue, Error, ErrorKind, FixedTag, Header,
+    Length, Reader, Result, Tag, Writer,
 };
 
 /// Byte used to encode `true` in ASN.1 DER. From X.690 Section 11.1:
@@ -33,7 +33,7 @@ impl EncodeValue for bool {
         Ok(Length::ONE)
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         writer.write_byte(if *self { TRUE_OCTET } else { FALSE_OCTET })
     }
 }
@@ -44,17 +44,6 @@ impl FixedTag for bool {
 
 impl OrdIsValueOrd for bool {}
 
-impl From<bool> for AnyRef<'static> {
-    fn from(value: bool) -> AnyRef<'static> {
-        let value = ByteSlice::from(match value {
-            false => &[FALSE_OCTET],
-            true => &[TRUE_OCTET],
-        });
-
-        AnyRef::from_tag_and_value(Tag::Boolean, value)
-    }
-}
-
 impl TryFrom<AnyRef<'_>> for bool {
     type Error = Error;
 
diff --git a/src/asn1/context_specific.rs b/src/asn1/context_specific.rs
index 311b5fe..101ddf0 100644
--- a/src/asn1/context_specific.rs
+++ b/src/asn1/context_specific.rs
@@ -145,7 +145,7 @@ where
         }
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         match self.tag_mode {
             TagMode::Explicit => self.value.encode(writer),
             TagMode::Implicit => self.value.encode_value(writer),
@@ -239,7 +239,7 @@ where
         self.encoder().value_len()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         self.encoder().encode_value(writer)
     }
 }
diff --git a/src/asn1/generalized_time.rs b/src/asn1/generalized_time.rs
index 9950e36..8837917 100644
--- a/src/asn1/generalized_time.rs
+++ b/src/asn1/generalized_time.rs
@@ -1,16 +1,18 @@
 //! ASN.1 `GeneralizedTime` support.
+#![cfg_attr(feature = "arbitrary", allow(clippy::integer_arithmetic))]
 
 use crate::{
-    asn1::AnyRef,
     datetime::{self, DateTime},
     ord::OrdIsValueOrd,
-    DecodeValue, EncodeValue, Error, ErrorKind, FixedTag, Header, Length, Reader, Result, Tag,
-    Writer,
+    DecodeValue, EncodeValue, ErrorKind, FixedTag, Header, Length, Reader, Result, Tag, Writer,
 };
 use core::time::Duration;
 
 #[cfg(feature = "std")]
-use std::time::SystemTime;
+use {
+    crate::{asn1::AnyRef, Error},
+    std::time::SystemTime,
+};
 
 #[cfg(feature = "time")]
 use time::PrimitiveDateTime;
@@ -26,6 +28,7 @@ use time::PrimitiveDateTime;
 /// > is zero.  GeneralizedTime values MUST NOT include fractional seconds.
 ///
 /// [1]: https://tools.ietf.org/html/rfc5280#section-4.1.2.5.2
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 pub struct GeneralizedTime(DateTime);
 
@@ -34,7 +37,7 @@ impl GeneralizedTime {
     const LENGTH: usize = 15;
 
     /// Create a [`GeneralizedTime`] from a [`DateTime`].
-    pub fn from_date_time(datetime: DateTime) -> Self {
+    pub const fn from_date_time(datetime: DateTime) -> Self {
         Self(datetime)
     }
 
@@ -58,7 +61,6 @@ impl GeneralizedTime {
 
     /// Instantiate from [`SystemTime`].
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn from_system_time(time: SystemTime) -> Result<Self> {
         DateTime::try_from(time)
             .map(Into::into)
@@ -67,12 +69,13 @@ impl GeneralizedTime {
 
     /// Convert to [`SystemTime`].
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn to_system_time(&self) -> SystemTime {
         self.0.to_system_time()
     }
 }
 
+impl_any_conversions!(GeneralizedTime);
+
 impl<'a> DecodeValue<'a> for GeneralizedTime {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         if Self::LENGTH != usize::try_from(header.length)? {
@@ -111,7 +114,7 @@ impl EncodeValue for GeneralizedTime {
         Self::LENGTH.try_into()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         let year_hi = u8::try_from(self.0.year() / 100)?;
         let year_lo = u8::try_from(self.0.year() % 100)?;
 
@@ -162,14 +165,6 @@ impl From<&DateTime> for GeneralizedTime {
     }
 }
 
-impl TryFrom<AnyRef<'_>> for GeneralizedTime {
-    type Error = Error;
-
-    fn try_from(any: AnyRef<'_>) -> Result<GeneralizedTime> {
-        any.decode_into()
-    }
-}
-
 impl<'a> DecodeValue<'a> for DateTime {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         Ok(GeneralizedTime::decode_value(reader, header)?.into())
@@ -181,7 +176,7 @@ impl EncodeValue for DateTime {
         GeneralizedTime::from(self).value_len()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         GeneralizedTime::from(self).encode_value(writer)
     }
 }
@@ -193,7 +188,6 @@ impl FixedTag for DateTime {
 impl OrdIsValueOrd for DateTime {}
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<'a> DecodeValue<'a> for SystemTime {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         Ok(GeneralizedTime::decode_value(reader, header)?.into())
@@ -201,19 +195,17 @@ impl<'a> DecodeValue<'a> for SystemTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl EncodeValue for SystemTime {
     fn value_len(&self) -> Result<Length> {
         GeneralizedTime::try_from(self)?.value_len()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         GeneralizedTime::try_from(self)?.encode_value(writer)
     }
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl From<GeneralizedTime> for SystemTime {
     fn from(time: GeneralizedTime) -> SystemTime {
         time.to_system_time()
@@ -221,7 +213,6 @@ impl From<GeneralizedTime> for SystemTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl From<&GeneralizedTime> for SystemTime {
     fn from(time: &GeneralizedTime) -> SystemTime {
         time.to_system_time()
@@ -229,7 +220,6 @@ impl From<&GeneralizedTime> for SystemTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl TryFrom<SystemTime> for GeneralizedTime {
     type Error = Error;
 
@@ -239,7 +229,6 @@ impl TryFrom<SystemTime> for GeneralizedTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl TryFrom<&SystemTime> for GeneralizedTime {
     type Error = Error;
 
@@ -249,7 +238,6 @@ impl TryFrom<&SystemTime> for GeneralizedTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<'a> TryFrom<AnyRef<'a>> for SystemTime {
     type Error = Error;
 
@@ -259,17 +247,14 @@ impl<'a> TryFrom<AnyRef<'a>> for SystemTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl FixedTag for SystemTime {
     const TAG: Tag = Tag::GeneralizedTime;
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl OrdIsValueOrd for SystemTime {}
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 impl<'a> DecodeValue<'a> for PrimitiveDateTime {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         GeneralizedTime::decode_value(reader, header)?.try_into()
@@ -277,29 +262,25 @@ impl<'a> DecodeValue<'a> for PrimitiveDateTime {
 }
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 impl EncodeValue for PrimitiveDateTime {
     fn value_len(&self) -> Result<Length> {
         GeneralizedTime::try_from(self)?.value_len()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         GeneralizedTime::try_from(self)?.encode_value(writer)
     }
 }
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 impl FixedTag for PrimitiveDateTime {
     const TAG: Tag = Tag::GeneralizedTime;
 }
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 impl OrdIsValueOrd for PrimitiveDateTime {}
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 impl TryFrom<PrimitiveDateTime> for GeneralizedTime {
     type Error = Error;
 
@@ -309,7 +290,6 @@ impl TryFrom<PrimitiveDateTime> for GeneralizedTime {
 }
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 impl TryFrom<&PrimitiveDateTime> for GeneralizedTime {
     type Error = Error;
 
@@ -319,7 +299,6 @@ impl TryFrom<&PrimitiveDateTime> for GeneralizedTime {
 }
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 impl TryFrom<GeneralizedTime> for PrimitiveDateTime {
     type Error = Error;
 
diff --git a/src/asn1/ia5_string.rs b/src/asn1/ia5_string.rs
index 3971270..1b06dce 100644
--- a/src/asn1/ia5_string.rs
+++ b/src/asn1/ia5_string.rs
@@ -1,10 +1,26 @@
 //! ASN.1 `IA5String` support.
 
-use crate::{
-    asn1::AnyRef, ord::OrdIsValueOrd, ByteSlice, DecodeValue, EncodeValue, Error, FixedTag, Header,
-    Length, Reader, Result, StrSlice, Tag, Writer,
-};
-use core::{fmt, ops::Deref, str};
+use crate::{asn1::AnyRef, FixedTag, Result, StrRef, Tag};
+use core::{fmt, ops::Deref};
+
+macro_rules! impl_ia5_string {
+    ($type: ty) => {
+        impl_ia5_string!($type,);
+    };
+    ($type: ty, $($li: lifetime)?) => {
+        impl_string_type!($type, $($li),*);
+
+        impl<$($li),*> FixedTag for $type {
+            const TAG: Tag = Tag::Ia5String;
+        }
+
+        impl<$($li),*> fmt::Debug for $type {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                write!(f, "Ia5String({:?})", self.as_str())
+            }
+        }
+    };
+}
 
 /// ASN.1 `IA5String` type.
 ///
@@ -21,7 +37,7 @@ use core::{fmt, ops::Deref, str};
 #[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord)]
 pub struct Ia5StringRef<'a> {
     /// Inner value
-    inner: StrSlice<'a>,
+    inner: StrRef<'a>,
 }
 
 impl<'a> Ia5StringRef<'a> {
@@ -37,83 +53,130 @@ impl<'a> Ia5StringRef<'a> {
             return Err(Self::TAG.value_error());
         }
 
-        StrSlice::from_bytes(input)
+        StrRef::from_bytes(input)
             .map(|inner| Self { inner })
             .map_err(|_| Self::TAG.value_error())
     }
 }
 
+impl_ia5_string!(Ia5StringRef<'a>, 'a);
+
 impl<'a> Deref for Ia5StringRef<'a> {
-    type Target = StrSlice<'a>;
+    type Target = StrRef<'a>;
 
     fn deref(&self) -> &Self::Target {
         &self.inner
     }
 }
 
-impl AsRef<str> for Ia5StringRef<'_> {
-    fn as_ref(&self) -> &str {
-        self.as_str()
+impl<'a> From<&Ia5StringRef<'a>> for Ia5StringRef<'a> {
+    fn from(value: &Ia5StringRef<'a>) -> Ia5StringRef<'a> {
+        *value
     }
 }
 
-impl AsRef<[u8]> for Ia5StringRef<'_> {
-    fn as_ref(&self) -> &[u8] {
-        self.as_bytes()
+impl<'a> From<Ia5StringRef<'a>> for AnyRef<'a> {
+    fn from(internationalized_string: Ia5StringRef<'a>) -> AnyRef<'a> {
+        AnyRef::from_tag_and_value(Tag::Ia5String, internationalized_string.inner.into())
     }
 }
 
-impl<'a> DecodeValue<'a> for Ia5StringRef<'a> {
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        Self::new(ByteSlice::decode_value(reader, header)?.as_slice())
-    }
-}
+#[cfg(feature = "alloc")]
+pub use self::allocation::Ia5String;
 
-impl EncodeValue for Ia5StringRef<'_> {
-    fn value_len(&self) -> Result<Length> {
-        self.inner.value_len()
+#[cfg(feature = "alloc")]
+mod allocation {
+    use super::Ia5StringRef;
+    use crate::{
+        asn1::AnyRef,
+        referenced::{OwnedToRef, RefToOwned},
+        Error, FixedTag, Result, StrOwned, Tag,
+    };
+    use alloc::string::String;
+    use core::{fmt, ops::Deref};
+
+    /// ASN.1 `IA5String` type.
+    ///
+    /// Supports the [International Alphabet No. 5 (IA5)] character encoding, i.e.
+    /// the lower 128 characters of the ASCII alphabet. (Note: IA5 is now
+    /// technically known as the International Reference Alphabet or IRA as
+    /// specified in the ITU-T's T.50 recommendation).
+    ///
+    /// For UTF-8, use [`String`][`alloc::string::String`].
+    ///
+    /// [International Alphabet No. 5 (IA5)]: https://en.wikipedia.org/wiki/T.50_%28standard%29
+    #[derive(Clone, Eq, PartialEq, PartialOrd, Ord)]
+    pub struct Ia5String {
+        /// Inner value
+        inner: StrOwned,
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        self.inner.encode_value(writer)
+    impl Ia5String {
+        /// Create a new `IA5String`.
+        pub fn new<T>(input: &T) -> Result<Self>
+        where
+            T: AsRef<[u8]> + ?Sized,
+        {
+            let input = input.as_ref();
+            Ia5StringRef::new(input)?;
+
+            StrOwned::from_bytes(input)
+                .map(|inner| Self { inner })
+                .map_err(|_| Self::TAG.value_error())
+        }
     }
-}
 
-impl<'a> FixedTag for Ia5StringRef<'a> {
-    const TAG: Tag = Tag::Ia5String;
-}
+    impl_ia5_string!(Ia5String);
 
-impl OrdIsValueOrd for Ia5StringRef<'_> {}
+    impl Deref for Ia5String {
+        type Target = StrOwned;
 
-impl<'a> From<&Ia5StringRef<'a>> for Ia5StringRef<'a> {
-    fn from(value: &Ia5StringRef<'a>) -> Ia5StringRef<'a> {
-        *value
+        fn deref(&self) -> &Self::Target {
+            &self.inner
+        }
     }
-}
 
-impl<'a> TryFrom<AnyRef<'a>> for Ia5StringRef<'a> {
-    type Error = Error;
+    impl<'a> From<Ia5StringRef<'a>> for Ia5String {
+        fn from(international_string: Ia5StringRef<'a>) -> Ia5String {
+            let inner = international_string.inner.into();
+            Self { inner }
+        }
+    }
 
-    fn try_from(any: AnyRef<'a>) -> Result<Ia5StringRef<'a>> {
-        any.decode_into()
+    impl<'a> From<&'a Ia5String> for AnyRef<'a> {
+        fn from(international_string: &'a Ia5String) -> AnyRef<'a> {
+            AnyRef::from_tag_and_value(Tag::Ia5String, (&international_string.inner).into())
+        }
     }
-}
 
-impl<'a> From<Ia5StringRef<'a>> for AnyRef<'a> {
-    fn from(printable_string: Ia5StringRef<'a>) -> AnyRef<'a> {
-        AnyRef::from_tag_and_value(Tag::Ia5String, printable_string.inner.into())
+    impl<'a> RefToOwned<'a> for Ia5StringRef<'a> {
+        type Owned = Ia5String;
+        fn ref_to_owned(&self) -> Self::Owned {
+            Ia5String {
+                inner: self.inner.ref_to_owned(),
+            }
+        }
     }
-}
 
-impl<'a> fmt::Display for Ia5StringRef<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(self.as_str())
+    impl OwnedToRef for Ia5String {
+        type Borrowed<'a> = Ia5StringRef<'a>;
+        fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+            Ia5StringRef {
+                inner: self.inner.owned_to_ref(),
+            }
+        }
     }
-}
 
-impl<'a> fmt::Debug for Ia5StringRef<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "Ia5String({:?})", self.as_str())
+    impl TryFrom<String> for Ia5String {
+        type Error = Error;
+
+        fn try_from(input: String) -> Result<Self> {
+            Ia5StringRef::new(&input)?;
+
+            StrOwned::new(input)
+                .map(|inner| Self { inner })
+                .map_err(|_| Self::TAG.value_error())
+        }
     }
 }
 
@@ -126,7 +189,7 @@ mod tests {
     #[test]
     fn parse_bytes() {
         let example_bytes = hex!("16 0d 74 65 73 74 31 40 72 73 61 2e 63 6f 6d");
-        let printable_string = Ia5StringRef::from_der(&example_bytes).unwrap();
-        assert_eq!(printable_string.as_str(), "test1@rsa.com");
+        let internationalized_string = Ia5StringRef::from_der(&example_bytes).unwrap();
+        assert_eq!(internationalized_string.as_str(), "test1@rsa.com");
     }
 }
diff --git a/src/asn1/integer.rs b/src/asn1/integer.rs
index 20e2f01..a6e913d 100644
--- a/src/asn1/integer.rs
+++ b/src/asn1/integer.rs
@@ -1,132 +1,17 @@
 //! ASN.1 `INTEGER` support.
 
-pub(super) mod bigint;
 pub(super) mod int;
 pub(super) mod uint;
 
-use crate::{
-    asn1::AnyRef, ByteSlice, DecodeValue, EncodeValue, Error, FixedTag, Header, Length, Reader,
-    Result, SliceWriter, Tag, ValueOrd, Writer,
-};
 use core::{cmp::Ordering, mem};
 
-macro_rules! impl_int_encoding {
-    ($($int:ty => $uint:ty),+) => {
-        $(
-            impl<'a> DecodeValue<'a> for $int {
-                fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-                    let bytes = ByteSlice::decode_value(reader, header)?.as_slice();
+use crate::{EncodeValue, Result, SliceWriter};
 
-                    let result = if is_highest_bit_set(bytes) {
-                        <$uint>::from_be_bytes(int::decode_to_array(bytes)?) as $int
-                    } else {
-                        Self::from_be_bytes(uint::decode_to_array(bytes)?)
-                    };
-
-                    // Ensure we compute the same encoded length as the original any value
-                    if header.length != result.value_len()? {
-                        return Err(Self::TAG.non_canonical_error());
-                    }
-
-                    Ok(result)
-                }
-            }
-
-            impl EncodeValue for $int {
-                fn value_len(&self) -> Result<Length> {
-                    if *self < 0 {
-                        int::encoded_len(&(*self as $uint).to_be_bytes())
-                    } else {
-                        uint::encoded_len(&self.to_be_bytes())
-                    }
-                }
-
-                fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-                    if *self < 0 {
-                        int::encode_bytes(writer, &(*self as $uint).to_be_bytes())
-                    } else {
-                        uint::encode_bytes(writer, &self.to_be_bytes())
-                    }
-                }
-            }
-
-            impl FixedTag for $int {
-                const TAG: Tag = Tag::Integer;
-            }
-
-            impl ValueOrd for $int {
-                fn value_cmp(&self, other: &Self) -> Result<Ordering> {
-                    value_cmp(*self, *other)
-                }
-            }
-
-            impl TryFrom<AnyRef<'_>> for $int {
-                type Error = Error;
-
-                fn try_from(any: AnyRef<'_>) -> Result<Self> {
-                    any.decode_into()
-                }
-            }
-        )+
-    };
-}
-
-macro_rules! impl_uint_encoding {
-    ($($uint:ty),+) => {
-        $(
-            impl<'a> DecodeValue<'a> for $uint {
-                fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-                    let bytes = ByteSlice::decode_value(reader, header)?.as_slice();
-                    let result = Self::from_be_bytes(uint::decode_to_array(bytes)?);
-
-                    // Ensure we compute the same encoded length as the original any value
-                    if header.length != result.value_len()? {
-                        return Err(Self::TAG.non_canonical_error());
-                    }
-
-                    Ok(result)
-                }
-            }
-
-            impl EncodeValue for $uint {
-                fn value_len(&self) -> Result<Length> {
-                    uint::encoded_len(&self.to_be_bytes())
-                }
-
-                fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-                    uint::encode_bytes(writer, &self.to_be_bytes())
-                }
-            }
-
-            impl FixedTag for $uint {
-                const TAG: Tag = Tag::Integer;
-            }
-
-            impl ValueOrd for $uint {
-                fn value_cmp(&self, other: &Self) -> Result<Ordering> {
-                    value_cmp(*self, *other)
-                }
-            }
-
-            impl TryFrom<AnyRef<'_>> for $uint {
-                type Error = Error;
-
-                fn try_from(any: AnyRef<'_>) -> Result<Self> {
-                    any.decode_into()
-                }
-            }
-        )+
-    };
-}
-
-impl_int_encoding!(i8 => u8, i16 => u16, i32 => u32, i64 => u64, i128 => u128);
-impl_uint_encoding!(u8, u16, u32, u64, u128);
-
-/// Is the highest bit of the first byte in the slice 1? (if present)
+/// Is the highest bit of the first byte in the slice set to `1`? (if present)
 #[inline]
 fn is_highest_bit_set(bytes: &[u8]) -> bool {
     bytes
-        .get(0)
+        .first()
         .map(|byte| byte & 0b10000000 != 0)
         .unwrap_or(false)
 }
diff --git a/src/asn1/integer/bigint.rs b/src/asn1/integer/bigint.rs
deleted file mode 100644
index f896406..0000000
--- a/src/asn1/integer/bigint.rs
+++ /dev/null
@@ -1,152 +0,0 @@
-//! "Big" ASN.1 `INTEGER` types.
-
-use super::uint;
-use crate::{
-    asn1::AnyRef, ord::OrdIsValueOrd, ByteSlice, DecodeValue, EncodeValue, Error, ErrorKind,
-    FixedTag, Header, Length, Reader, Result, Tag, Writer,
-};
-
-/// "Big" unsigned ASN.1 `INTEGER` type.
-///
-/// Provides direct access to the underlying big endian bytes which comprise an
-/// unsigned integer value.
-///
-/// Intended for use cases like very large integers that are used in
-/// cryptographic applications (e.g. keys, signatures).
-#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
-pub struct UIntRef<'a> {
-    /// Inner value
-    inner: ByteSlice<'a>,
-}
-
-impl<'a> UIntRef<'a> {
-    /// Create a new [`UIntRef`] from a byte slice.
-    pub fn new(bytes: &'a [u8]) -> Result<Self> {
-        let inner = ByteSlice::new(uint::strip_leading_zeroes(bytes))
-            .map_err(|_| ErrorKind::Length { tag: Self::TAG })?;
-
-        Ok(Self { inner })
-    }
-
-    /// Borrow the inner byte slice which contains the least significant bytes
-    /// of a big endian integer value with all leading zeros stripped.
-    pub fn as_bytes(&self) -> &'a [u8] {
-        self.inner.as_slice()
-    }
-
-    /// Get the length of this [`UIntRef`] in bytes.
-    pub fn len(&self) -> Length {
-        self.inner.len()
-    }
-
-    /// Is the inner byte slice empty?
-    pub fn is_empty(&self) -> bool {
-        self.inner.is_empty()
-    }
-}
-
-impl<'a> DecodeValue<'a> for UIntRef<'a> {
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        let bytes = ByteSlice::decode_value(reader, header)?.as_slice();
-        let result = Self::new(uint::decode_to_slice(bytes)?)?;
-
-        // Ensure we compute the same encoded length as the original any value.
-        if result.value_len()? != header.length {
-            return Err(Self::TAG.non_canonical_error());
-        }
-
-        Ok(result)
-    }
-}
-
-impl<'a> EncodeValue for UIntRef<'a> {
-    fn value_len(&self) -> Result<Length> {
-        uint::encoded_len(self.inner.as_slice())
-    }
-
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        // Add leading `0x00` byte if required
-        if self.value_len()? > self.len() {
-            writer.write_byte(0)?;
-        }
-
-        writer.write(self.as_bytes())
-    }
-}
-
-impl<'a> From<&UIntRef<'a>> for UIntRef<'a> {
-    fn from(value: &UIntRef<'a>) -> UIntRef<'a> {
-        *value
-    }
-}
-
-impl<'a> TryFrom<AnyRef<'a>> for UIntRef<'a> {
-    type Error = Error;
-
-    fn try_from(any: AnyRef<'a>) -> Result<UIntRef<'a>> {
-        any.decode_into()
-    }
-}
-
-impl<'a> FixedTag for UIntRef<'a> {
-    const TAG: Tag = Tag::Integer;
-}
-
-impl<'a> OrdIsValueOrd for UIntRef<'a> {}
-
-#[cfg(test)]
-mod tests {
-    use super::UIntRef;
-    use crate::{
-        asn1::{integer::tests::*, AnyRef},
-        Decode, Encode, ErrorKind, SliceWriter, Tag,
-    };
-
-    #[test]
-    fn decode_uint_bytes() {
-        assert_eq!(&[0], UIntRef::from_der(I0_BYTES).unwrap().as_bytes());
-        assert_eq!(&[127], UIntRef::from_der(I127_BYTES).unwrap().as_bytes());
-        assert_eq!(&[128], UIntRef::from_der(I128_BYTES).unwrap().as_bytes());
-        assert_eq!(&[255], UIntRef::from_der(I255_BYTES).unwrap().as_bytes());
-
-        assert_eq!(
-            &[0x01, 0x00],
-            UIntRef::from_der(I256_BYTES).unwrap().as_bytes()
-        );
-
-        assert_eq!(
-            &[0x7F, 0xFF],
-            UIntRef::from_der(I32767_BYTES).unwrap().as_bytes()
-        );
-    }
-
-    #[test]
-    fn encode_uint_bytes() {
-        for &example in &[
-            I0_BYTES,
-            I127_BYTES,
-            I128_BYTES,
-            I255_BYTES,
-            I256_BYTES,
-            I32767_BYTES,
-        ] {
-            let uint = UIntRef::from_der(example).unwrap();
-
-            let mut buf = [0u8; 128];
-            let mut encoder = SliceWriter::new(&mut buf);
-            uint.encode(&mut encoder).unwrap();
-
-            let result = encoder.finish().unwrap();
-            assert_eq!(example, result);
-        }
-    }
-
-    #[test]
-    fn reject_oversize_without_extra_zero() {
-        let err = UIntRef::try_from(AnyRef::new(Tag::Integer, &[0x81]).unwrap())
-            .err()
-            .unwrap();
-
-        assert_eq!(err.kind(), ErrorKind::Value { tag: Tag::Integer });
-    }
-}
diff --git a/src/asn1/integer/int.rs b/src/asn1/integer/int.rs
index a9fe438..bccc521 100644
--- a/src/asn1/integer/int.rs
+++ b/src/asn1/integer/int.rs
@@ -1,12 +1,310 @@
-//! Support for encoding negative integers
+//! Support for encoding signed integers
 
-use super::is_highest_bit_set;
-use crate::{ErrorKind, Length, Result, Writer};
+use super::{is_highest_bit_set, uint, value_cmp};
+use crate::{
+    ord::OrdIsValueOrd, AnyRef, BytesRef, DecodeValue, EncodeValue, Error, ErrorKind, FixedTag,
+    Header, Length, Reader, Result, Tag, ValueOrd, Writer,
+};
+use core::cmp::Ordering;
 
-/// Decode an unsigned integer of the specified size.
+#[cfg(feature = "alloc")]
+pub use allocating::Int;
+
+macro_rules! impl_encoding_traits {
+    ($($int:ty => $uint:ty),+) => {
+        $(
+            impl<'a> DecodeValue<'a> for $int {
+                fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+                    let mut buf = [0u8; Self::BITS as usize / 8];
+                    let max_length = u32::from(header.length) as usize;
+
+                    if max_length > buf.len() {
+                        return Err(Self::TAG.non_canonical_error());
+                    }
+
+                    let bytes = reader.read_into(&mut buf[..max_length])?;
+
+                    let result = if is_highest_bit_set(bytes) {
+                        <$uint>::from_be_bytes(decode_to_array(bytes)?) as $int
+                    } else {
+                        Self::from_be_bytes(uint::decode_to_array(bytes)?)
+                    };
+
+                    // Ensure we compute the same encoded length as the original any value
+                    if header.length != result.value_len()? {
+                        return Err(Self::TAG.non_canonical_error());
+                    }
+
+                    Ok(result)
+                }
+            }
+
+            impl EncodeValue for $int {
+                fn value_len(&self) -> Result<Length> {
+                    if *self < 0 {
+                        negative_encoded_len(&(*self as $uint).to_be_bytes())
+                    } else {
+                        uint::encoded_len(&self.to_be_bytes())
+                    }
+                }
+
+                fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+                    if *self < 0 {
+                        encode_bytes(writer, &(*self as $uint).to_be_bytes())
+                    } else {
+                        uint::encode_bytes(writer, &self.to_be_bytes())
+                    }
+                }
+            }
+
+            impl FixedTag for $int {
+                const TAG: Tag = Tag::Integer;
+            }
+
+            impl ValueOrd for $int {
+                fn value_cmp(&self, other: &Self) -> Result<Ordering> {
+                    value_cmp(*self, *other)
+                }
+            }
+
+            impl TryFrom<AnyRef<'_>> for $int {
+                type Error = Error;
+
+                fn try_from(any: AnyRef<'_>) -> Result<Self> {
+                    any.decode_as()
+                }
+            }
+        )+
+    };
+}
+
+impl_encoding_traits!(i8 => u8, i16 => u16, i32 => u32, i64 => u64, i128 => u128);
+
+/// Signed arbitrary precision ASN.1 `INTEGER` reference type.
+///
+/// Provides direct access to the underlying big endian bytes which comprise
+/// an signed integer value.
+///
+/// Intended for use cases like very large integers that are used in
+/// cryptographic applications (e.g. keys, signatures).
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+pub struct IntRef<'a> {
+    /// Inner value
+    inner: BytesRef<'a>,
+}
+
+impl<'a> IntRef<'a> {
+    /// Create a new [`IntRef`] from a byte slice.
+    pub fn new(bytes: &'a [u8]) -> Result<Self> {
+        let inner = BytesRef::new(strip_leading_ones(bytes))
+            .map_err(|_| ErrorKind::Length { tag: Self::TAG })?;
+
+        Ok(Self { inner })
+    }
+
+    /// Borrow the inner byte slice which contains the least significant bytes
+    /// of a big endian integer value with all leading ones stripped.
+    pub fn as_bytes(&self) -> &'a [u8] {
+        self.inner.as_slice()
+    }
+
+    /// Get the length of this [`IntRef`] in bytes.
+    pub fn len(&self) -> Length {
+        self.inner.len()
+    }
+
+    /// Is the inner byte slice empty?
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+}
+
+impl_any_conversions!(IntRef<'a>, 'a);
+
+impl<'a> DecodeValue<'a> for IntRef<'a> {
+    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+        let bytes = BytesRef::decode_value(reader, header)?;
+        validate_canonical(bytes.as_slice())?;
+
+        let result = Self::new(bytes.as_slice())?;
+
+        // Ensure we compute the same encoded length as the original any value.
+        if result.value_len()? != header.length {
+            return Err(Self::TAG.non_canonical_error());
+        }
+
+        Ok(result)
+    }
+}
+
+impl<'a> EncodeValue for IntRef<'a> {
+    fn value_len(&self) -> Result<Length> {
+        // Signed integers always hold their full encoded form.
+        Ok(self.inner.len())
+    }
+
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+        writer.write(self.as_bytes())
+    }
+}
+
+impl<'a> From<&IntRef<'a>> for IntRef<'a> {
+    fn from(value: &IntRef<'a>) -> IntRef<'a> {
+        *value
+    }
+}
+
+impl<'a> FixedTag for IntRef<'a> {
+    const TAG: Tag = Tag::Integer;
+}
+
+impl<'a> OrdIsValueOrd for IntRef<'a> {}
+
+#[cfg(feature = "alloc")]
+mod allocating {
+    use super::{strip_leading_ones, validate_canonical, IntRef};
+    use crate::{
+        asn1::Uint,
+        ord::OrdIsValueOrd,
+        referenced::{OwnedToRef, RefToOwned},
+        BytesOwned, DecodeValue, EncodeValue, ErrorKind, FixedTag, Header, Length, Reader, Result,
+        Tag, Writer,
+    };
+    use alloc::vec::Vec;
+
+    /// Signed arbitrary precision ASN.1 `INTEGER` type.
+    ///
+    /// Provides heap-allocated storage for big endian bytes which comprise an
+    /// signed integer value.
+    ///
+    /// Intended for use cases like very large integers that are used in
+    /// cryptographic applications (e.g. keys, signatures).
+    #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+    pub struct Int {
+        /// Inner value
+        inner: BytesOwned,
+    }
+
+    impl Int {
+        /// Create a new [`Int`] from a byte slice.
+        pub fn new(bytes: &[u8]) -> Result<Self> {
+            let inner = BytesOwned::new(strip_leading_ones(bytes))
+                .map_err(|_| ErrorKind::Length { tag: Self::TAG })?;
+
+            Ok(Self { inner })
+        }
+
+        /// Borrow the inner byte slice which contains the least significant bytes
+        /// of a big endian integer value with all leading ones stripped.
+        pub fn as_bytes(&self) -> &[u8] {
+            self.inner.as_slice()
+        }
+
+        /// Get the length of this [`Int`] in bytes.
+        pub fn len(&self) -> Length {
+            self.inner.len()
+        }
+
+        /// Is the inner byte slice empty?
+        pub fn is_empty(&self) -> bool {
+            self.inner.is_empty()
+        }
+    }
+
+    impl_any_conversions!(Int);
+
+    impl<'a> DecodeValue<'a> for Int {
+        fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+            let bytes = BytesOwned::decode_value(reader, header)?;
+            validate_canonical(bytes.as_slice())?;
+
+            let result = Self::new(bytes.as_slice())?;
+
+            // Ensure we compute the same encoded length as the original any value.
+            if result.value_len()? != header.length {
+                return Err(Self::TAG.non_canonical_error());
+            }
+
+            Ok(result)
+        }
+    }
+
+    impl EncodeValue for Int {
+        fn value_len(&self) -> Result<Length> {
+            // Signed integers always hold their full encoded form.
+            Ok(self.inner.len())
+        }
+
+        fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+            writer.write(self.as_bytes())
+        }
+    }
+
+    impl<'a> From<&IntRef<'a>> for Int {
+        fn from(value: &IntRef<'a>) -> Int {
+            let inner = BytesOwned::new(value.as_bytes()).expect("Invalid Int");
+            Int { inner }
+        }
+    }
+
+    impl From<Uint> for Int {
+        fn from(value: Uint) -> Self {
+            let mut inner: Vec<u8> = Vec::new();
+
+            // Add leading `0x00` byte if required
+            if value.value_len().expect("invalid Uint") > value.len() {
+                inner.push(0x00);
+            }
+
+            inner.extend_from_slice(value.as_bytes());
+            let inner = BytesOwned::new(inner).expect("invalid Uint");
+
+            Int { inner }
+        }
+    }
+
+    impl FixedTag for Int {
+        const TAG: Tag = Tag::Integer;
+    }
+
+    impl OrdIsValueOrd for Int {}
+
+    impl<'a> RefToOwned<'a> for IntRef<'a> {
+        type Owned = Int;
+        fn ref_to_owned(&self) -> Self::Owned {
+            let inner = self.inner.ref_to_owned();
+
+            Int { inner }
+        }
+    }
+
+    impl OwnedToRef for Int {
+        type Borrowed<'a> = IntRef<'a>;
+        fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+            let inner = self.inner.owned_to_ref();
+
+            IntRef { inner }
+        }
+    }
+}
+
+/// Ensure `INTEGER` is canonically encoded.
+fn validate_canonical(bytes: &[u8]) -> Result<()> {
+    // The `INTEGER` type always encodes a signed value and we're decoding
+    // as signed here, so we allow a zero extension or sign extension byte,
+    // but only as permitted under DER canonicalization.
+    match bytes {
+        [] => Err(Tag::Integer.non_canonical_error()),
+        [0x00, byte, ..] if *byte < 0x80 => Err(Tag::Integer.non_canonical_error()),
+        [0xFF, byte, ..] if *byte >= 0x80 => Err(Tag::Integer.non_canonical_error()),
+        _ => Ok(()),
+    }
+}
+
+/// Decode an signed integer of the specified size.
 ///
 /// Returns a byte array of the requested size containing a big endian integer.
-pub(super) fn decode_to_array<const N: usize>(bytes: &[u8]) -> Result<[u8; N]> {
+fn decode_to_array<const N: usize>(bytes: &[u8]) -> Result<[u8; N]> {
     match N.checked_sub(bytes.len()) {
         Some(offset) => {
             let mut output = [0xFFu8; N];
@@ -27,21 +325,21 @@ pub(super) fn decode_to_array<const N: usize>(bytes: &[u8]) -> Result<[u8; N]> {
 }
 
 /// Encode the given big endian bytes representing an integer as ASN.1 DER.
-pub(super) fn encode_bytes<W>(writer: &mut W, bytes: &[u8]) -> Result<()>
+fn encode_bytes<W>(writer: &mut W, bytes: &[u8]) -> Result<()>
 where
     W: Writer + ?Sized,
 {
     writer.write(strip_leading_ones(bytes))
 }
 
-/// Get the encoded length for the given unsigned integer serialized as bytes.
+/// Get the encoded length for the given **negative** integer serialized as bytes.
 #[inline]
-pub(super) fn encoded_len(bytes: &[u8]) -> Result<Length> {
+fn negative_encoded_len(bytes: &[u8]) -> Result<Length> {
     Length::try_from(strip_leading_ones(bytes).len())
 }
 
 /// Strip the leading all-ones bytes from the given byte slice.
-fn strip_leading_ones(mut bytes: &[u8]) -> &[u8] {
+pub(crate) fn strip_leading_ones(mut bytes: &[u8]) -> &[u8] {
     while let Some((byte, rest)) = bytes.split_first() {
         if *byte == 0xFF && is_highest_bit_set(rest) {
             bytes = rest;
@@ -53,3 +351,92 @@ fn strip_leading_ones(mut bytes: &[u8]) -> &[u8] {
 
     bytes
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{validate_canonical, IntRef};
+    use crate::{asn1::integer::tests::*, Decode, Encode, SliceWriter};
+
+    #[test]
+    fn validate_canonical_ok() {
+        assert_eq!(validate_canonical(&[0x00]), Ok(()));
+        assert_eq!(validate_canonical(&[0x01]), Ok(()));
+        assert_eq!(validate_canonical(&[0x00, 0x80]), Ok(()));
+        assert_eq!(validate_canonical(&[0xFF, 0x00]), Ok(()));
+    }
+
+    #[test]
+    fn validate_canonical_err() {
+        // Empty integers are always non-canonical.
+        assert!(validate_canonical(&[]).is_err());
+
+        // Positives with excessive zero extension are non-canonical.
+        assert!(validate_canonical(&[0x00, 0x00]).is_err());
+
+        // Negatives with excessive sign extension are non-canonical.
+        assert!(validate_canonical(&[0xFF, 0x80]).is_err());
+    }
+
+    #[test]
+    fn decode_intref() {
+        // Positive numbers decode, but have zero extensions as necessary
+        // (to distinguish them from negative representations).
+        assert_eq!(&[0], IntRef::from_der(I0_BYTES).unwrap().as_bytes());
+        assert_eq!(&[127], IntRef::from_der(I127_BYTES).unwrap().as_bytes());
+        assert_eq!(&[0, 128], IntRef::from_der(I128_BYTES).unwrap().as_bytes());
+        assert_eq!(&[0, 255], IntRef::from_der(I255_BYTES).unwrap().as_bytes());
+
+        assert_eq!(
+            &[0x01, 0x00],
+            IntRef::from_der(I256_BYTES).unwrap().as_bytes()
+        );
+
+        assert_eq!(
+            &[0x7F, 0xFF],
+            IntRef::from_der(I32767_BYTES).unwrap().as_bytes()
+        );
+
+        // Negative integers decode.
+        assert_eq!(&[128], IntRef::from_der(INEG128_BYTES).unwrap().as_bytes());
+        assert_eq!(
+            &[255, 127],
+            IntRef::from_der(INEG129_BYTES).unwrap().as_bytes()
+        );
+        assert_eq!(
+            &[128, 0],
+            IntRef::from_der(INEG32768_BYTES).unwrap().as_bytes()
+        );
+    }
+
+    #[test]
+    fn encode_intref() {
+        for &example in &[
+            I0_BYTES,
+            I127_BYTES,
+            I128_BYTES,
+            I255_BYTES,
+            I256_BYTES,
+            I32767_BYTES,
+        ] {
+            let uint = IntRef::from_der(example).unwrap();
+
+            let mut buf = [0u8; 128];
+            let mut encoder = SliceWriter::new(&mut buf);
+            uint.encode(&mut encoder).unwrap();
+
+            let result = encoder.finish().unwrap();
+            assert_eq!(example, result);
+        }
+
+        for &example in &[INEG128_BYTES, INEG129_BYTES, INEG32768_BYTES] {
+            let uint = IntRef::from_der(example).unwrap();
+
+            let mut buf = [0u8; 128];
+            let mut encoder = SliceWriter::new(&mut buf);
+            uint.encode(&mut encoder).unwrap();
+
+            let result = encoder.finish().unwrap();
+            assert_eq!(example, result);
+        }
+    }
+}
diff --git a/src/asn1/integer/uint.rs b/src/asn1/integer/uint.rs
index e45a72f..95c6297 100644
--- a/src/asn1/integer/uint.rs
+++ b/src/asn1/integer/uint.rs
@@ -1,6 +1,270 @@
 //! Unsigned integer decoders/encoders.
 
-use crate::{Length, Result, Tag, Writer};
+use super::value_cmp;
+use crate::{
+    ord::OrdIsValueOrd, AnyRef, BytesRef, DecodeValue, EncodeValue, Error, ErrorKind, FixedTag,
+    Header, Length, Reader, Result, Tag, ValueOrd, Writer,
+};
+use core::cmp::Ordering;
+
+#[cfg(feature = "alloc")]
+pub use allocating::Uint;
+
+macro_rules! impl_encoding_traits {
+    ($($uint:ty),+) => {
+        $(
+            impl<'a> DecodeValue<'a> for $uint {
+                fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+                    // Integers always encodes as a signed value, unsigned gets a leading 0x00 that
+                    // needs to be stripped off. We need to provide room for it.
+                    const UNSIGNED_HEADROOM: usize = 1;
+
+                    let mut buf = [0u8; (Self::BITS as usize / 8) + UNSIGNED_HEADROOM];
+                    let max_length = u32::from(header.length) as usize;
+
+                    if max_length > buf.len() {
+                        return Err(Self::TAG.non_canonical_error());
+                    }
+
+                    let bytes = reader.read_into(&mut buf[..max_length])?;
+
+                    let result = Self::from_be_bytes(decode_to_array(bytes)?);
+
+                    // Ensure we compute the same encoded length as the original any value
+                    if header.length != result.value_len()? {
+                        return Err(Self::TAG.non_canonical_error());
+                    }
+
+                    Ok(result)
+                }
+            }
+
+            impl EncodeValue for $uint {
+                fn value_len(&self) -> Result<Length> {
+                    encoded_len(&self.to_be_bytes())
+                }
+
+                fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+                    encode_bytes(writer, &self.to_be_bytes())
+                }
+            }
+
+            impl FixedTag for $uint {
+                const TAG: Tag = Tag::Integer;
+            }
+
+            impl ValueOrd for $uint {
+                fn value_cmp(&self, other: &Self) -> Result<Ordering> {
+                    value_cmp(*self, *other)
+                }
+            }
+
+            impl TryFrom<AnyRef<'_>> for $uint {
+                type Error = Error;
+
+                fn try_from(any: AnyRef<'_>) -> Result<Self> {
+                    any.decode_as()
+                }
+            }
+        )+
+    };
+}
+
+impl_encoding_traits!(u8, u16, u32, u64, u128);
+
+/// Unsigned arbitrary precision ASN.1 `INTEGER` reference type.
+///
+/// Provides direct access to the underlying big endian bytes which comprise an
+/// unsigned integer value.
+///
+/// Intended for use cases like very large integers that are used in
+/// cryptographic applications (e.g. keys, signatures).
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+pub struct UintRef<'a> {
+    /// Inner value
+    inner: BytesRef<'a>,
+}
+
+impl<'a> UintRef<'a> {
+    /// Create a new [`UintRef`] from a byte slice.
+    pub fn new(bytes: &'a [u8]) -> Result<Self> {
+        let inner = BytesRef::new(strip_leading_zeroes(bytes))
+            .map_err(|_| ErrorKind::Length { tag: Self::TAG })?;
+
+        Ok(Self { inner })
+    }
+
+    /// Borrow the inner byte slice which contains the least significant bytes
+    /// of a big endian integer value with all leading zeros stripped.
+    pub fn as_bytes(&self) -> &'a [u8] {
+        self.inner.as_slice()
+    }
+
+    /// Get the length of this [`UintRef`] in bytes.
+    pub fn len(&self) -> Length {
+        self.inner.len()
+    }
+
+    /// Is the inner byte slice empty?
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+}
+
+impl_any_conversions!(UintRef<'a>, 'a);
+
+impl<'a> DecodeValue<'a> for UintRef<'a> {
+    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+        let bytes = BytesRef::decode_value(reader, header)?.as_slice();
+        let result = Self::new(decode_to_slice(bytes)?)?;
+
+        // Ensure we compute the same encoded length as the original any value.
+        if result.value_len()? != header.length {
+            return Err(Self::TAG.non_canonical_error());
+        }
+
+        Ok(result)
+    }
+}
+
+impl<'a> EncodeValue for UintRef<'a> {
+    fn value_len(&self) -> Result<Length> {
+        encoded_len(self.inner.as_slice())
+    }
+
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+        // Add leading `0x00` byte if required
+        if self.value_len()? > self.len() {
+            writer.write_byte(0)?;
+        }
+
+        writer.write(self.as_bytes())
+    }
+}
+
+impl<'a> From<&UintRef<'a>> for UintRef<'a> {
+    fn from(value: &UintRef<'a>) -> UintRef<'a> {
+        *value
+    }
+}
+
+impl<'a> FixedTag for UintRef<'a> {
+    const TAG: Tag = Tag::Integer;
+}
+
+impl<'a> OrdIsValueOrd for UintRef<'a> {}
+
+#[cfg(feature = "alloc")]
+mod allocating {
+    use super::{decode_to_slice, encoded_len, strip_leading_zeroes, UintRef};
+    use crate::{
+        ord::OrdIsValueOrd,
+        referenced::{OwnedToRef, RefToOwned},
+        BytesOwned, DecodeValue, EncodeValue, ErrorKind, FixedTag, Header, Length, Reader, Result,
+        Tag, Writer,
+    };
+
+    /// Unsigned arbitrary precision ASN.1 `INTEGER` type.
+    ///
+    /// Provides heap-allocated storage for big endian bytes which comprise an
+    /// unsigned integer value.
+    ///
+    /// Intended for use cases like very large integers that are used in
+    /// cryptographic applications (e.g. keys, signatures).
+    #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+    pub struct Uint {
+        /// Inner value
+        inner: BytesOwned,
+    }
+
+    impl Uint {
+        /// Create a new [`Uint`] from a byte slice.
+        pub fn new(bytes: &[u8]) -> Result<Self> {
+            let inner = BytesOwned::new(strip_leading_zeroes(bytes))
+                .map_err(|_| ErrorKind::Length { tag: Self::TAG })?;
+
+            Ok(Self { inner })
+        }
+
+        /// Borrow the inner byte slice which contains the least significant bytes
+        /// of a big endian integer value with all leading zeros stripped.
+        pub fn as_bytes(&self) -> &[u8] {
+            self.inner.as_slice()
+        }
+
+        /// Get the length of this [`Uint`] in bytes.
+        pub fn len(&self) -> Length {
+            self.inner.len()
+        }
+
+        /// Is the inner byte slice empty?
+        pub fn is_empty(&self) -> bool {
+            self.inner.is_empty()
+        }
+    }
+
+    impl_any_conversions!(Uint);
+
+    impl<'a> DecodeValue<'a> for Uint {
+        fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+            let bytes = BytesOwned::decode_value(reader, header)?;
+            let result = Self::new(decode_to_slice(bytes.as_slice())?)?;
+
+            // Ensure we compute the same encoded length as the original any value.
+            if result.value_len()? != header.length {
+                return Err(Self::TAG.non_canonical_error());
+            }
+
+            Ok(result)
+        }
+    }
+
+    impl EncodeValue for Uint {
+        fn value_len(&self) -> Result<Length> {
+            encoded_len(self.inner.as_slice())
+        }
+
+        fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+            // Add leading `0x00` byte if required
+            if self.value_len()? > self.len() {
+                writer.write_byte(0)?;
+            }
+
+            writer.write(self.as_bytes())
+        }
+    }
+
+    impl<'a> From<&UintRef<'a>> for Uint {
+        fn from(value: &UintRef<'a>) -> Uint {
+            let inner = BytesOwned::new(value.as_bytes()).expect("Invalid Uint");
+            Uint { inner }
+        }
+    }
+
+    impl FixedTag for Uint {
+        const TAG: Tag = Tag::Integer;
+    }
+
+    impl OrdIsValueOrd for Uint {}
+
+    impl<'a> RefToOwned<'a> for UintRef<'a> {
+        type Owned = Uint;
+        fn ref_to_owned(&self) -> Self::Owned {
+            let inner = self.inner.ref_to_owned();
+
+            Uint { inner }
+        }
+    }
+
+    impl OwnedToRef for Uint {
+        type Borrowed<'a> = UintRef<'a>;
+        fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+            let inner = self.inner.owned_to_ref();
+
+            UintRef { inner }
+        }
+    }
+}
 
 /// Decode an unsigned integer into a big endian byte slice with all leading
 /// zeroes removed.
@@ -75,13 +339,13 @@ pub(crate) fn strip_leading_zeroes(mut bytes: &[u8]) -> &[u8] {
 
 /// Does the given integer need a leading zero?
 fn needs_leading_zero(bytes: &[u8]) -> bool {
-    matches!(bytes.get(0), Some(byte) if *byte >= 0x80)
+    matches!(bytes.first(), Some(byte) if *byte >= 0x80)
 }
 
 #[cfg(test)]
 mod tests {
-    use super::decode_to_array;
-    use crate::{ErrorKind, Tag};
+    use super::{decode_to_array, UintRef};
+    use crate::{asn1::integer::tests::*, AnyRef, Decode, Encode, ErrorKind, SliceWriter, Tag};
 
     #[test]
     fn decode_to_array_no_leading_zero() {
@@ -113,4 +377,52 @@ mod tests {
         let err = decode_to_array::<1>(&[1, 2, 3]).err().unwrap();
         assert_eq!(err.kind(), ErrorKind::Length { tag: Tag::Integer });
     }
+
+    #[test]
+    fn decode_uintref() {
+        assert_eq!(&[0], UintRef::from_der(I0_BYTES).unwrap().as_bytes());
+        assert_eq!(&[127], UintRef::from_der(I127_BYTES).unwrap().as_bytes());
+        assert_eq!(&[128], UintRef::from_der(I128_BYTES).unwrap().as_bytes());
+        assert_eq!(&[255], UintRef::from_der(I255_BYTES).unwrap().as_bytes());
+
+        assert_eq!(
+            &[0x01, 0x00],
+            UintRef::from_der(I256_BYTES).unwrap().as_bytes()
+        );
+
+        assert_eq!(
+            &[0x7F, 0xFF],
+            UintRef::from_der(I32767_BYTES).unwrap().as_bytes()
+        );
+    }
+
+    #[test]
+    fn encode_uintref() {
+        for &example in &[
+            I0_BYTES,
+            I127_BYTES,
+            I128_BYTES,
+            I255_BYTES,
+            I256_BYTES,
+            I32767_BYTES,
+        ] {
+            let uint = UintRef::from_der(example).unwrap();
+
+            let mut buf = [0u8; 128];
+            let mut encoder = SliceWriter::new(&mut buf);
+            uint.encode(&mut encoder).unwrap();
+
+            let result = encoder.finish().unwrap();
+            assert_eq!(example, result);
+        }
+    }
+
+    #[test]
+    fn reject_oversize_without_extra_zero() {
+        let err = UintRef::try_from(AnyRef::new(Tag::Integer, &[0x81]).unwrap())
+            .err()
+            .unwrap();
+
+        assert_eq!(err.kind(), ErrorKind::Value { tag: Tag::Integer });
+    }
 }
diff --git a/src/asn1/internal_macros.rs b/src/asn1/internal_macros.rs
new file mode 100644
index 0000000..10ad99d
--- /dev/null
+++ b/src/asn1/internal_macros.rs
@@ -0,0 +1,75 @@
+macro_rules! impl_any_conversions {
+    ($type: ty) => {
+        impl_any_conversions!($type, );
+    };
+    ($type: ty, $($li: lifetime)?) => {
+        impl<'__der: $($li),*, $($li),*> TryFrom<$crate::AnyRef<'__der>> for $type {
+            type Error = $crate::Error;
+
+            fn try_from(any: $crate::AnyRef<'__der>) -> Result<$type> {
+                any.decode_as()
+            }
+        }
+
+        #[cfg(feature = "alloc")]
+        impl<'__der: $($li),*, $($li),*> TryFrom<&'__der $crate::Any> for $type {
+            type Error = $crate::Error;
+
+            fn try_from(any: &'__der $crate::Any) -> Result<$type> {
+                any.decode_as()
+            }
+        }
+    };
+}
+
+macro_rules! impl_string_type {
+    ($type: ty, $($li: lifetime)?) => {
+        impl_any_conversions!($type, $($li),*);
+
+        mod __impl_string {
+            use super::*;
+
+            use crate::{
+                ord::OrdIsValueOrd, BytesRef, DecodeValue, EncodeValue, Header, Length, Reader,
+                Result, Writer,
+            };
+            use core::{fmt, str};
+
+            impl<$($li),*> AsRef<str> for $type {
+                fn as_ref(&self) -> &str {
+                    self.as_str()
+                }
+            }
+
+            impl<$($li),*> AsRef<[u8]> for $type {
+                fn as_ref(&self) -> &[u8] {
+                    self.as_bytes()
+                }
+            }
+
+            impl<'__der: $($li),*, $($li),*> DecodeValue<'__der> for $type {
+                fn decode_value<R: Reader<'__der>>(reader: &mut R, header: Header) -> Result<Self> {
+                    Self::new(BytesRef::decode_value(reader, header)?.as_slice())
+                }
+            }
+
+            impl<$($li),*> EncodeValue for $type {
+                fn value_len(&self) -> Result<Length> {
+                    self.inner.value_len()
+                }
+
+                fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+                    self.inner.encode_value(writer)
+                }
+            }
+
+            impl<$($li),*> OrdIsValueOrd for $type {}
+
+            impl<$($li),*> fmt::Display for $type {
+                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    f.write_str(self.as_str())
+                }
+            }
+        }
+    };
+}
diff --git a/src/asn1/null.rs b/src/asn1/null.rs
index e87729f..7c1e205 100644
--- a/src/asn1/null.rs
+++ b/src/asn1/null.rs
@@ -1,7 +1,7 @@
 //! ASN.1 `NULL` support.
 
 use crate::{
-    asn1::AnyRef, ord::OrdIsValueOrd, ByteSlice, DecodeValue, EncodeValue, Error, ErrorKind,
+    asn1::AnyRef, ord::OrdIsValueOrd, BytesRef, DecodeValue, EncodeValue, Error, ErrorKind,
     FixedTag, Header, Length, Reader, Result, Tag, Writer,
 };
 
@@ -9,6 +9,8 @@ use crate::{
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 pub struct Null;
 
+impl_any_conversions!(Null);
+
 impl<'a> DecodeValue<'a> for Null {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         if header.length.is_zero() {
@@ -24,7 +26,7 @@ impl EncodeValue for Null {
         Ok(Length::ZERO)
     }
 
-    fn encode_value(&self, _writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, _writer: &mut impl Writer) -> Result<()> {
         Ok(())
     }
 }
@@ -37,15 +39,7 @@ impl OrdIsValueOrd for Null {}
 
 impl<'a> From<Null> for AnyRef<'a> {
     fn from(_: Null) -> AnyRef<'a> {
-        AnyRef::from_tag_and_value(Tag::Null, ByteSlice::default())
-    }
-}
-
-impl TryFrom<AnyRef<'_>> for Null {
-    type Error = Error;
-
-    fn try_from(any: AnyRef<'_>) -> Result<Null> {
-        any.decode_into()
+        AnyRef::from_tag_and_value(Tag::Null, BytesRef::default())
     }
 }
 
@@ -75,7 +69,7 @@ impl EncodeValue for () {
         Ok(Length::ZERO)
     }
 
-    fn encode_value(&self, _writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, _writer: &mut impl Writer) -> Result<()> {
         Ok(())
     }
 }
diff --git a/src/asn1/octet_string.rs b/src/asn1/octet_string.rs
index 6f5b91a..53d8ecb 100644
--- a/src/asn1/octet_string.rs
+++ b/src/asn1/octet_string.rs
@@ -1,13 +1,10 @@
 //! ASN.1 `OCTET STRING` support.
 
 use crate::{
-    asn1::AnyRef, ord::OrdIsValueOrd, ByteSlice, DecodeValue, EncodeValue, Error, ErrorKind,
+    asn1::AnyRef, ord::OrdIsValueOrd, BytesRef, Decode, DecodeValue, EncodeValue, ErrorKind,
     FixedTag, Header, Length, Reader, Result, Tag, Writer,
 };
 
-#[cfg(feature = "alloc")]
-use alloc::vec::Vec;
-
 /// ASN.1 `OCTET STRING` type: borrowed form.
 ///
 /// Octet strings represent contiguous sequences of octets, a.k.a. bytes.
@@ -16,13 +13,13 @@ use alloc::vec::Vec;
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 pub struct OctetStringRef<'a> {
     /// Inner value
-    inner: ByteSlice<'a>,
+    inner: BytesRef<'a>,
 }
 
 impl<'a> OctetStringRef<'a> {
     /// Create a new ASN.1 `OCTET STRING` from a byte slice.
     pub fn new(slice: &'a [u8]) -> Result<Self> {
-        ByteSlice::new(slice)
+        BytesRef::new(slice)
             .map(|inner| Self { inner })
             .map_err(|_| ErrorKind::Length { tag: Self::TAG }.into())
     }
@@ -41,8 +38,15 @@ impl<'a> OctetStringRef<'a> {
     pub fn is_empty(&self) -> bool {
         self.inner.is_empty()
     }
+
+    /// Parse `T` from this `OCTET STRING`'s contents.
+    pub fn decode_into<T: Decode<'a>>(&self) -> Result<T> {
+        Decode::from_der(self.as_bytes())
+    }
 }
 
+impl_any_conversions!(OctetStringRef<'a>, 'a);
+
 impl AsRef<[u8]> for OctetStringRef<'_> {
     fn as_ref(&self) -> &[u8] {
         self.as_bytes()
@@ -51,7 +55,7 @@ impl AsRef<[u8]> for OctetStringRef<'_> {
 
 impl<'a> DecodeValue<'a> for OctetStringRef<'a> {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        let inner = ByteSlice::decode_value(reader, header)?;
+        let inner = BytesRef::decode_value(reader, header)?;
         Ok(Self { inner })
     }
 }
@@ -61,7 +65,7 @@ impl EncodeValue for OctetStringRef<'_> {
         self.inner.value_len()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         self.inner.encode_value(writer)
     }
 }
@@ -78,14 +82,6 @@ impl<'a> From<&OctetStringRef<'a>> for OctetStringRef<'a> {
     }
 }
 
-impl<'a> TryFrom<AnyRef<'a>> for OctetStringRef<'a> {
-    type Error = Error;
-
-    fn try_from(any: AnyRef<'a>) -> Result<OctetStringRef<'a>> {
-        any.decode_into()
-    }
-}
-
 impl<'a> From<OctetStringRef<'a>> for AnyRef<'a> {
     fn from(octet_string: OctetStringRef<'a>) -> AnyRef<'a> {
         AnyRef::from_tag_and_value(Tag::OctetString, octet_string.inner)
@@ -98,85 +94,164 @@ impl<'a> From<OctetStringRef<'a>> for &'a [u8] {
     }
 }
 
-/// ASN.1 `OCTET STRING` type: owned form..
-///
-/// Octet strings represent contiguous sequences of octets, a.k.a. bytes.
-///
-/// This type provides the same functionality as [`OctetStringRef`] but owns
-/// the backing data.
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
-#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
-pub struct OctetString {
-    /// Bitstring represented as a slice of bytes.
-    inner: Vec<u8>,
-}
+pub use self::allocating::OctetString;
 
 #[cfg(feature = "alloc")]
-impl OctetString {
-    /// Create a new ASN.1 `OCTET STRING`.
-    pub fn new(bytes: impl Into<Vec<u8>>) -> Result<Self> {
-        let inner = bytes.into();
+mod allocating {
+    use super::*;
+    use crate::referenced::*;
+    use alloc::vec::Vec;
+
+    /// ASN.1 `OCTET STRING` type: owned form..
+    ///
+    /// Octet strings represent contiguous sequences of octets, a.k.a. bytes.
+    ///
+    /// This type provides the same functionality as [`OctetStringRef`] but owns
+    /// the backing data.
+    #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+    pub struct OctetString {
+        /// Bitstring represented as a slice of bytes.
+        pub(super) inner: Vec<u8>,
+    }
 
-        // Ensure the bytes parse successfully as an `OctetStringRef`
-        OctetStringRef::new(&inner)?;
+    impl OctetString {
+        /// Create a new ASN.1 `OCTET STRING`.
+        pub fn new(bytes: impl Into<Vec<u8>>) -> Result<Self> {
+            let inner = bytes.into();
 
-        Ok(Self { inner })
+            // Ensure the bytes parse successfully as an `OctetStringRef`
+            OctetStringRef::new(&inner)?;
+
+            Ok(Self { inner })
+        }
+
+        /// Borrow the inner byte slice.
+        pub fn as_bytes(&self) -> &[u8] {
+            self.inner.as_slice()
+        }
+
+        /// Take ownership of the octet string.
+        pub fn into_bytes(self) -> Vec<u8> {
+            self.inner
+        }
+
+        /// Get the length of the inner byte slice.
+        pub fn len(&self) -> Length {
+            self.value_len().expect("invalid OCTET STRING length")
+        }
+
+        /// Is the inner byte slice empty?
+        pub fn is_empty(&self) -> bool {
+            self.inner.is_empty()
+        }
     }
 
-    /// Borrow the inner byte slice.
-    pub fn as_bytes(&self) -> &[u8] {
-        self.inner.as_slice()
+    impl_any_conversions!(OctetString);
+
+    impl AsRef<[u8]> for OctetString {
+        fn as_ref(&self) -> &[u8] {
+            self.as_bytes()
+        }
     }
 
-    /// Get the length of the inner byte slice.
-    pub fn len(&self) -> Length {
-        self.value_len().expect("invalid OCTET STRING length")
+    impl<'a> DecodeValue<'a> for OctetString {
+        fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+            Self::new(reader.read_vec(header.length)?)
+        }
     }
 
-    /// Is the inner byte slice empty?
-    pub fn is_empty(&self) -> bool {
-        self.inner.is_empty()
+    impl EncodeValue for OctetString {
+        fn value_len(&self) -> Result<Length> {
+            self.inner.len().try_into()
+        }
+
+        fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+            writer.write(&self.inner)
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl AsRef<[u8]> for OctetString {
-    fn as_ref(&self) -> &[u8] {
-        self.as_bytes()
+    impl FixedTag for OctetString {
+        const TAG: Tag = Tag::OctetString;
     }
-}
 
-#[cfg(feature = "alloc")]
-impl<'a> DecodeValue<'a> for OctetString {
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        Self::new(reader.read_vec(header.length)?)
+    impl<'a> From<&'a OctetString> for OctetStringRef<'a> {
+        fn from(octet_string: &'a OctetString) -> OctetStringRef<'a> {
+            // Ensured to parse successfully in constructor
+            OctetStringRef::new(&octet_string.inner).expect("invalid OCTET STRING")
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl EncodeValue for OctetString {
-    fn value_len(&self) -> Result<Length> {
-        self.inner.len().try_into()
+    impl OrdIsValueOrd for OctetString {}
+
+    impl<'a> RefToOwned<'a> for OctetStringRef<'a> {
+        type Owned = OctetString;
+        fn ref_to_owned(&self) -> Self::Owned {
+            OctetString {
+                inner: Vec::from(self.inner.as_slice()),
+            }
+        }
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        writer.write(&self.inner)
+    impl OwnedToRef for OctetString {
+        type Borrowed<'a> = OctetStringRef<'a>;
+        fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+            self.into()
+        }
     }
-}
 
-#[cfg(feature = "alloc")]
-impl FixedTag for OctetString {
-    const TAG: Tag = Tag::OctetString;
+    // Implement by hand because the derive would create invalid values.
+    // Use the constructor to create a valid value.
+    #[cfg(feature = "arbitrary")]
+    impl<'a> arbitrary::Arbitrary<'a> for OctetString {
+        fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+            Self::new(Vec::arbitrary(u)?).map_err(|_| arbitrary::Error::IncorrectFormat)
+        }
+
+        fn size_hint(depth: usize) -> (usize, Option<usize>) {
+            arbitrary::size_hint::and(u8::size_hint(depth), Vec::<u8>::size_hint(depth))
+        }
+    }
 }
 
-#[cfg(feature = "alloc")]
-impl<'a> From<&'a OctetString> for OctetStringRef<'a> {
-    fn from(octet_string: &'a OctetString) -> OctetStringRef<'a> {
-        // Ensured to parse successfully in constructor
-        OctetStringRef::new(&octet_string.inner).expect("invalid OCTET STRING")
+#[cfg(feature = "bytes")]
+mod bytes {
+    use super::OctetString;
+    use crate::{DecodeValue, EncodeValue, FixedTag, Header, Length, Reader, Result, Tag, Writer};
+    use bytes::Bytes;
+
+    impl<'a> DecodeValue<'a> for Bytes {
+        fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+            OctetString::decode_value(reader, header).map(|octet_string| octet_string.inner.into())
+        }
+    }
+
+    impl EncodeValue for Bytes {
+        fn value_len(&self) -> Result<Length> {
+            self.len().try_into()
+        }
+
+        fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+            writer.write(self.as_ref())
+        }
+    }
+
+    impl FixedTag for Bytes {
+        const TAG: Tag = Tag::OctetString;
     }
 }
 
-#[cfg(feature = "alloc")]
-impl OrdIsValueOrd for OctetString {}
+#[cfg(test)]
+mod tests {
+    use crate::asn1::{OctetStringRef, PrintableStringRef};
+
+    #[test]
+    fn octet_string_decode_into() {
+        // PrintableString "hi"
+        let der = b"\x13\x02\x68\x69";
+        let oct = OctetStringRef::new(der).unwrap();
+
+        let res = oct.decode_into::<PrintableStringRef<'_>>().unwrap();
+        assert_eq!(AsRef::<str>::as_ref(&res), "hi");
+    }
+}
diff --git a/src/asn1/oid.rs b/src/asn1/oid.rs
index 8b28718..3daa452 100644
--- a/src/asn1/oid.rs
+++ b/src/asn1/oid.rs
@@ -6,6 +6,9 @@ use crate::{
 };
 use const_oid::ObjectIdentifier;
 
+#[cfg(feature = "alloc")]
+use super::Any;
+
 impl<'a> DecodeValue<'a> for ObjectIdentifier {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         let mut buf = [0u8; ObjectIdentifier::MAX_SIZE];
@@ -24,7 +27,7 @@ impl EncodeValue for ObjectIdentifier {
         Length::try_from(self.as_bytes().len())
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         writer.write(self.as_bytes())
     }
 }
@@ -50,6 +53,13 @@ impl<'a> From<&'a ObjectIdentifier> for AnyRef<'a> {
     }
 }
 
+#[cfg(feature = "alloc")]
+impl From<ObjectIdentifier> for Any {
+    fn from(oid: ObjectIdentifier) -> Any {
+        AnyRef::from(&oid).into()
+    }
+}
+
 impl TryFrom<AnyRef<'_>> for ObjectIdentifier {
     type Error = Error;
 
diff --git a/src/asn1/optional.rs b/src/asn1/optional.rs
index a9b923c..ecda4f8 100644
--- a/src/asn1/optional.rs
+++ b/src/asn1/optional.rs
@@ -41,7 +41,7 @@ where
         (&self).encoded_len()
     }
 
-    fn encode(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode(&self, writer: &mut impl Writer) -> Result<()> {
         (&self).encode(writer)
     }
 }
@@ -57,7 +57,7 @@ where
         }
     }
 
-    fn encode(&self, encoder: &mut dyn Writer) -> Result<()> {
+    fn encode(&self, encoder: &mut impl Writer) -> Result<()> {
         match self {
             Some(encodable) => encodable.encode(encoder),
             None => Ok(()),
diff --git a/src/asn1/printable_string.rs b/src/asn1/printable_string.rs
index d48f90f..d2e51d7 100644
--- a/src/asn1/printable_string.rs
+++ b/src/asn1/printable_string.rs
@@ -1,10 +1,26 @@
 //! ASN.1 `PrintableString` support.
 
-use crate::{
-    asn1::AnyRef, ord::OrdIsValueOrd, ByteSlice, DecodeValue, EncodeValue, Error, FixedTag, Header,
-    Length, Reader, Result, StrSlice, Tag, Writer,
-};
-use core::{fmt, ops::Deref, str};
+use crate::{asn1::AnyRef, FixedTag, Result, StrRef, Tag};
+use core::{fmt, ops::Deref};
+
+macro_rules! impl_printable_string {
+    ($type: ty) => {
+        impl_printable_string!($type,);
+    };
+    ($type: ty, $($li: lifetime)?) => {
+        impl_string_type!($type, $($li),*);
+
+        impl<$($li),*> FixedTag for $type {
+            const TAG: Tag = Tag::PrintableString;
+        }
+
+        impl<$($li),*> fmt::Debug for $type {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                write!(f, "PrintableString({:?})", self.as_str())
+            }
+        }
+    };
+}
 
 /// ASN.1 `PrintableString` type.
 ///
@@ -38,7 +54,7 @@ use core::{fmt, ops::Deref, str};
 #[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord)]
 pub struct PrintableStringRef<'a> {
     /// Inner value
-    inner: StrSlice<'a>,
+    inner: StrRef<'a>,
 }
 
 impl<'a> PrintableStringRef<'a> {
@@ -71,83 +87,151 @@ impl<'a> PrintableStringRef<'a> {
             }
         }
 
-        StrSlice::from_bytes(input)
+        StrRef::from_bytes(input)
             .map(|inner| Self { inner })
             .map_err(|_| Self::TAG.value_error())
     }
 }
 
+impl_printable_string!(PrintableStringRef<'a>, 'a);
+
 impl<'a> Deref for PrintableStringRef<'a> {
-    type Target = StrSlice<'a>;
+    type Target = StrRef<'a>;
 
     fn deref(&self) -> &Self::Target {
         &self.inner
     }
 }
-
-impl AsRef<str> for PrintableStringRef<'_> {
-    fn as_ref(&self) -> &str {
-        self.as_str()
+impl<'a> From<&PrintableStringRef<'a>> for PrintableStringRef<'a> {
+    fn from(value: &PrintableStringRef<'a>) -> PrintableStringRef<'a> {
+        *value
     }
 }
 
-impl AsRef<[u8]> for PrintableStringRef<'_> {
-    fn as_ref(&self) -> &[u8] {
-        self.as_bytes()
+impl<'a> From<PrintableStringRef<'a>> for AnyRef<'a> {
+    fn from(printable_string: PrintableStringRef<'a>) -> AnyRef<'a> {
+        AnyRef::from_tag_and_value(Tag::PrintableString, printable_string.inner.into())
     }
 }
 
-impl<'a> DecodeValue<'a> for PrintableStringRef<'a> {
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        Self::new(ByteSlice::decode_value(reader, header)?.as_slice())
-    }
-}
+#[cfg(feature = "alloc")]
+pub use self::allocation::PrintableString;
+
+#[cfg(feature = "alloc")]
+mod allocation {
+    use super::PrintableStringRef;
 
-impl<'a> EncodeValue for PrintableStringRef<'a> {
-    fn value_len(&self) -> Result<Length> {
-        self.inner.value_len()
+    use crate::{
+        asn1::AnyRef,
+        referenced::{OwnedToRef, RefToOwned},
+        BytesRef, Error, FixedTag, Result, StrOwned, Tag,
+    };
+    use alloc::string::String;
+    use core::{fmt, ops::Deref};
+
+    /// ASN.1 `PrintableString` type.
+    ///
+    /// Supports a subset the ASCII character set (described below).
+    ///
+    /// For UTF-8, use [`Utf8StringRef`][`crate::asn1::Utf8StringRef`] instead.
+    /// For the full ASCII character set, use
+    /// [`Ia5StringRef`][`crate::asn1::Ia5StringRef`].
+    ///
+    /// # Supported characters
+    ///
+    /// The following ASCII characters/ranges are supported:
+    ///
+    /// - `A..Z`
+    /// - `a..z`
+    /// - `0..9`
+    /// - "` `" (i.e. space)
+    /// - `\`
+    /// - `(`
+    /// - `)`
+    /// - `+`
+    /// - `,`
+    /// - `-`
+    /// - `.`
+    /// - `/`
+    /// - `:`
+    /// - `=`
+    /// - `?`
+    #[derive(Clone, Eq, PartialEq, PartialOrd, Ord)]
+    pub struct PrintableString {
+        /// Inner value
+        inner: StrOwned,
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        self.inner.encode_value(writer)
+    impl PrintableString {
+        /// Create a new ASN.1 `PrintableString`.
+        pub fn new<T>(input: &T) -> Result<Self>
+        where
+            T: AsRef<[u8]> + ?Sized,
+        {
+            let input = input.as_ref();
+            PrintableStringRef::new(input)?;
+
+            StrOwned::from_bytes(input)
+                .map(|inner| Self { inner })
+                .map_err(|_| Self::TAG.value_error())
+        }
     }
-}
 
-impl FixedTag for PrintableStringRef<'_> {
-    const TAG: Tag = Tag::PrintableString;
-}
+    impl_printable_string!(PrintableString);
 
-impl OrdIsValueOrd for PrintableStringRef<'_> {}
+    impl Deref for PrintableString {
+        type Target = StrOwned;
 
-impl<'a> From<&PrintableStringRef<'a>> for PrintableStringRef<'a> {
-    fn from(value: &PrintableStringRef<'a>) -> PrintableStringRef<'a> {
-        *value
+        fn deref(&self) -> &Self::Target {
+            &self.inner
+        }
     }
-}
 
-impl<'a> TryFrom<AnyRef<'a>> for PrintableStringRef<'a> {
-    type Error = Error;
+    impl<'a> From<PrintableStringRef<'a>> for PrintableString {
+        fn from(value: PrintableStringRef<'a>) -> PrintableString {
+            let inner =
+                StrOwned::from_bytes(value.inner.as_bytes()).expect("Invalid PrintableString");
+            Self { inner }
+        }
+    }
 
-    fn try_from(any: AnyRef<'a>) -> Result<PrintableStringRef<'a>> {
-        any.decode_into()
+    impl<'a> From<&'a PrintableString> for AnyRef<'a> {
+        fn from(printable_string: &'a PrintableString) -> AnyRef<'a> {
+            AnyRef::from_tag_and_value(
+                Tag::PrintableString,
+                BytesRef::new(printable_string.inner.as_bytes()).expect("Invalid PrintableString"),
+            )
+        }
     }
-}
 
-impl<'a> From<PrintableStringRef<'a>> for AnyRef<'a> {
-    fn from(printable_string: PrintableStringRef<'a>) -> AnyRef<'a> {
-        AnyRef::from_tag_and_value(Tag::PrintableString, printable_string.inner.into())
+    impl<'a> RefToOwned<'a> for PrintableStringRef<'a> {
+        type Owned = PrintableString;
+        fn ref_to_owned(&self) -> Self::Owned {
+            PrintableString {
+                inner: self.inner.ref_to_owned(),
+            }
+        }
     }
-}
 
-impl<'a> fmt::Display for PrintableStringRef<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(self.as_str())
+    impl OwnedToRef for PrintableString {
+        type Borrowed<'a> = PrintableStringRef<'a>;
+        fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+            PrintableStringRef {
+                inner: self.inner.owned_to_ref(),
+            }
+        }
     }
-}
 
-impl<'a> fmt::Debug for PrintableStringRef<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "PrintableString({:?})", self.as_str())
+    impl TryFrom<String> for PrintableString {
+        type Error = Error;
+
+        fn try_from(input: String) -> Result<Self> {
+            PrintableStringRef::new(&input)?;
+
+            StrOwned::new(input)
+                .map(|inner| Self { inner })
+                .map_err(|_| Self::TAG.value_error())
+        }
     }
 }
 
diff --git a/src/asn1/real.rs b/src/asn1/real.rs
index f872d2d..b9f2e67 100644
--- a/src/asn1/real.rs
+++ b/src/asn1/real.rs
@@ -8,22 +8,21 @@
 )]
 
 use crate::{
-    str_slice::StrSlice, ByteSlice, DecodeValue, EncodeValue, FixedTag, Header, Length, Reader,
-    Result, Tag, Writer,
+    BytesRef, DecodeValue, EncodeValue, FixedTag, Header, Length, Reader, Result, StrRef, Tag,
+    Writer,
 };
 
 use super::integer::uint::strip_leading_zeroes;
 
-#[cfg_attr(docsrs, doc(cfg(feature = "real")))]
 impl<'a> DecodeValue<'a> for f64 {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        let bytes = ByteSlice::decode_value(reader, header)?.as_slice();
+        let bytes = BytesRef::decode_value(reader, header)?.as_slice();
 
         if header.length == Length::ZERO {
             Ok(0.0)
         } else if is_nth_bit_one::<7>(bytes) {
             // Binary encoding from section 8.5.7 applies
-            let sign: u64 = if is_nth_bit_one::<6>(bytes) { 1 } else { 0 };
+            let sign: u64 = u64::from(is_nth_bit_one::<6>(bytes));
 
             // Section 8.5.7.2: Check the base -- the DER specs say that only base 2 should be supported in DER
             let base = mnth_bits_to_u8::<5, 4>(bytes);
@@ -74,7 +73,7 @@ impl<'a> DecodeValue<'a> for f64 {
                 _ => Err(Tag::Real.value_error()),
             }
         } else {
-            let astr = StrSlice::from_bytes(&bytes[1..])?;
+            let astr = StrRef::from_bytes(&bytes[1..])?;
             match astr.inner.parse::<f64>() {
                 Ok(val) => Ok(val),
                 // Real related error: encoding not supported or malformed
@@ -84,7 +83,6 @@ impl<'a> DecodeValue<'a> for f64 {
     }
 }
 
-#[cfg_attr(docsrs, doc(cfg(feature = "real")))]
 impl EncodeValue for f64 {
     fn value_len(&self) -> Result<Length> {
         if self.is_sign_positive() && (*self) < f64::MIN_POSITIVE {
@@ -120,7 +118,7 @@ impl EncodeValue for f64 {
         }
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         // Check if special value
         // Encode zero first, if it's zero
         // Special value from section 8.5.9 if non zero
@@ -194,7 +192,6 @@ impl EncodeValue for f64 {
     }
 }
 
-#[cfg_attr(docsrs, doc(cfg(feature = "real")))]
 impl FixedTag for f64 {
     const TAG: Tag = Tag::Real;
 }
@@ -204,7 +201,7 @@ impl FixedTag for f64 {
 pub(crate) fn is_nth_bit_one<const N: usize>(bytes: &[u8]) -> bool {
     if N < 8 {
         bytes
-            .get(0)
+            .first()
             .map(|byte| byte & (1 << N) != 0)
             .unwrap_or(false)
     } else {
diff --git a/src/asn1/sequence.rs b/src/asn1/sequence.rs
index d2f6bc5..ad4a5d5 100644
--- a/src/asn1/sequence.rs
+++ b/src/asn1/sequence.rs
@@ -2,69 +2,40 @@
 //! `SEQUENCE`s to Rust structs.
 
 use crate::{
-    ByteSlice, Decode, DecodeValue, Encode, EncodeValue, FixedTag, Header, Length, Reader, Result,
-    Tag, Writer,
+    BytesRef, DecodeValue, EncodeValue, FixedTag, Header, Length, Reader, Result, Tag, Writer,
 };
 
-/// ASN.1 `SEQUENCE` trait.
-///
-/// Types which impl this trait receive blanket impls for the [`Decode`],
-/// [`Encode`], and [`FixedTag`] traits.
-pub trait Sequence<'a>: Decode<'a> {
-    /// Call the provided function with a slice of [`Encode`] trait objects
-    /// representing the fields of this `SEQUENCE`.
-    ///
-    /// This method uses a callback because structs with fields which aren't
-    /// directly [`Encode`] may need to construct temporary values from
-    /// their fields prior to encoding.
-    fn fields<F, T>(&self, f: F) -> Result<T>
-    where
-        F: FnOnce(&[&dyn Encode]) -> Result<T>;
-}
-
-impl<'a, M> EncodeValue for M
-where
-    M: Sequence<'a>,
-{
-    fn value_len(&self) -> Result<Length> {
-        self.fields(|fields| {
-            fields
-                .iter()
-                .try_fold(Length::ZERO, |acc, field| acc + field.encoded_len()?)
-        })
-    }
+#[cfg(feature = "alloc")]
+use alloc::boxed::Box;
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        self.fields(|fields| {
-            for &field in fields {
-                field.encode(writer)?;
-            }
-
-            Ok(())
-        })
-    }
-}
+/// Marker trait for ASN.1 `SEQUENCE`s.
+///
+/// This is mainly used for custom derive.
+pub trait Sequence<'a>: DecodeValue<'a> + EncodeValue {}
 
-impl<'a, M> FixedTag for M
+impl<'a, S> FixedTag for S
 where
-    M: Sequence<'a>,
+    S: Sequence<'a>,
 {
     const TAG: Tag = Tag::Sequence;
 }
 
+#[cfg(feature = "alloc")]
+impl<'a, T> Sequence<'a> for Box<T> where T: Sequence<'a> {}
+
 /// The [`SequenceRef`] type provides raw access to the octets which comprise a
 /// DER-encoded `SEQUENCE`.
 ///
 /// This is a zero-copy reference type which borrows from the input data.
 pub struct SequenceRef<'a> {
     /// Body of the `SEQUENCE`.
-    body: ByteSlice<'a>,
+    body: BytesRef<'a>,
 }
 
 impl<'a> DecodeValue<'a> for SequenceRef<'a> {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         Ok(Self {
-            body: ByteSlice::decode_value(reader, header)?,
+            body: BytesRef::decode_value(reader, header)?,
         })
     }
 }
@@ -74,11 +45,9 @@ impl EncodeValue for SequenceRef<'_> {
         Ok(self.body.len())
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         self.body.encode_value(writer)
     }
 }
 
-impl<'a> FixedTag for SequenceRef<'a> {
-    const TAG: Tag = Tag::Sequence;
-}
+impl<'a> Sequence<'a> for SequenceRef<'a> {}
diff --git a/src/asn1/sequence_of.rs b/src/asn1/sequence_of.rs
index 6334d71..befb029 100644
--- a/src/asn1/sequence_of.rs
+++ b/src/asn1/sequence_of.rs
@@ -30,7 +30,7 @@ impl<T, const N: usize> SequenceOf<T, N> {
 
     /// Add an element to this [`SequenceOf`].
     pub fn add(&mut self, element: T) -> Result<()> {
-        self.inner.add(element)
+        self.inner.push(element)
     }
 
     /// Get an element of this [`SequenceOf`].
@@ -88,7 +88,7 @@ where
             .fold(Ok(Length::ZERO), |len, elem| len + elem.encoded_len()?)
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         for elem in self.iter() {
             elem.encode(writer)?;
         }
@@ -155,7 +155,7 @@ where
             .fold(Ok(Length::ZERO), |len, elem| len + elem.encoded_len()?)
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         for elem in self {
             elem.encode(writer)?;
         }
@@ -178,7 +178,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<'a, T> DecodeValue<'a> for Vec<T>
 where
     T: Decode<'a>,
@@ -197,7 +196,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T> EncodeValue for Vec<T>
 where
     T: Encode,
@@ -207,7 +205,7 @@ where
             .fold(Ok(Length::ZERO), |len, elem| len + elem.encoded_len()?)
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         for elem in self {
             elem.encode(writer)?;
         }
@@ -217,13 +215,11 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T> FixedTag for Vec<T> {
     const TAG: Tag = Tag::Sequence;
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T> ValueOrd for Vec<T>
 where
     T: DerOrd,
diff --git a/src/asn1/set_of.rs b/src/asn1/set_of.rs
index b8c4b0d..ff01312 100644
--- a/src/asn1/set_of.rs
+++ b/src/asn1/set_of.rs
@@ -44,19 +44,32 @@ where
         }
     }
 
-    /// Add an element to this [`SetOf`].
+    /// Add an item to this [`SetOf`].
     ///
     /// Items MUST be added in lexicographical order according to the
     /// [`DerOrd`] impl on `T`.
+    #[deprecated(since = "0.7.6", note = "use `insert` or `insert_ordered` instead")]
     pub fn add(&mut self, new_elem: T) -> Result<()> {
+        self.insert_ordered(new_elem)
+    }
+
+    /// Insert an item into this [`SetOf`].
+    pub fn insert(&mut self, item: T) -> Result<()> {
+        self.inner.push(item)?;
+        der_sort(self.inner.as_mut())
+    }
+
+    /// Insert an item into this [`SetOf`].
+    ///
+    /// Items MUST be added in lexicographical order according to the
+    /// [`DerOrd`] impl on `T`.
+    pub fn insert_ordered(&mut self, item: T) -> Result<()> {
         // Ensure set elements are lexicographically ordered
-        if let Some(last_elem) = self.inner.last() {
-            if new_elem.der_cmp(last_elem)? != Ordering::Greater {
-                return Err(ErrorKind::SetOrdering.into());
-            }
+        if let Some(last) = self.inner.last() {
+            check_der_ordering(last, &item)?;
         }
 
-        self.inner.add(new_elem)
+        self.inner.push(item)
     }
 
     /// Get the nth element from this [`SetOf`].
@@ -100,7 +113,7 @@ where
             let mut result = Self::new();
 
             while !reader.is_finished() {
-                result.inner.add(T::decode(reader)?)?;
+                result.inner.push(T::decode(reader)?)?;
             }
 
             der_sort(result.inner.as_mut())?;
@@ -119,7 +132,7 @@ where
             .fold(Ok(Length::ZERO), |len, elem| len + elem.encoded_len()?)
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         for elem in self.iter() {
             elem.encode(writer)?;
         }
@@ -147,7 +160,7 @@ where
         let mut result = SetOf::new();
 
         for elem in arr {
-            result.add(elem)?;
+            result.insert_ordered(elem)?;
         }
 
         Ok(result)
@@ -185,7 +198,6 @@ impl<'a, T> ExactSizeIterator for SetOfIter<'a, T> {}
 /// This type implements an append-only `SET OF` type which is heap-backed
 /// and depends on `alloc` support.
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 pub struct SetOfVec<T>
 where
@@ -195,7 +207,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T: DerOrd> Default for SetOfVec<T> {
     fn default() -> Self {
         Self {
@@ -205,7 +216,6 @@ impl<T: DerOrd> Default for SetOfVec<T> {
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T> SetOfVec<T>
 where
     T: DerOrd,
@@ -217,19 +227,56 @@ where
         }
     }
 
+    /// Create a new [`SetOfVec`] from the given iterator.
+    ///
+    /// Note: this is an inherent method instead of an impl of the
+    /// [`FromIterator`] trait in order to be fallible.
+    #[allow(clippy::should_implement_trait)]
+    pub fn from_iter<I>(iter: I) -> Result<Self>
+    where
+        I: IntoIterator<Item = T>,
+    {
+        Vec::from_iter(iter).try_into()
+    }
+
     /// Add an element to this [`SetOfVec`].
     ///
     /// Items MUST be added in lexicographical order according to the
     /// [`DerOrd`] impl on `T`.
-    pub fn add(&mut self, new_elem: T) -> Result<()> {
+    #[deprecated(since = "0.7.6", note = "use `insert` or `insert_ordered` instead")]
+    pub fn add(&mut self, item: T) -> Result<()> {
+        self.insert_ordered(item)
+    }
+
+    /// Extend a [`SetOfVec`] using an iterator.
+    ///
+    /// Note: this is an inherent method instead of an impl of the
+    /// [`Extend`] trait in order to be fallible.
+    pub fn extend<I>(&mut self, iter: I) -> Result<()>
+    where
+        I: IntoIterator<Item = T>,
+    {
+        self.inner.extend(iter);
+        der_sort(&mut self.inner)
+    }
+
+    /// Insert an item into this [`SetOfVec`]. Must be unique.
+    pub fn insert(&mut self, item: T) -> Result<()> {
+        self.inner.push(item);
+        der_sort(&mut self.inner)
+    }
+
+    /// Insert an item into this [`SetOfVec`]. Must be unique.
+    ///
+    /// Items MUST be added in lexicographical order according to the
+    /// [`DerOrd`] impl on `T`.
+    pub fn insert_ordered(&mut self, item: T) -> Result<()> {
         // Ensure set elements are lexicographically ordered
-        if let Some(last_elem) = self.inner.last() {
-            if new_elem.der_cmp(last_elem)? != Ordering::Greater {
-                return Err(ErrorKind::SetOrdering.into());
-            }
+        if let Some(last) = self.inner.last() {
+            check_der_ordering(last, &item)?;
         }
 
-        self.inner.push(new_elem);
+        self.inner.push(item);
         Ok(())
     }
 
@@ -265,7 +312,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T> AsRef<[T]> for SetOfVec<T>
 where
     T: DerOrd,
@@ -276,7 +322,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<'a, T> DecodeValue<'a> for SetOfVec<T>
 where
     T: Decode<'a> + DerOrd,
@@ -297,7 +342,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<'a, T> EncodeValue for SetOfVec<T>
 where
     T: 'a + Decode<'a> + Encode + DerOrd,
@@ -307,7 +351,7 @@ where
             .fold(Ok(Length::ZERO), |len, elem| len + elem.encoded_len()?)
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         for elem in self.iter() {
             elem.encode(writer)?;
         }
@@ -317,7 +361,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T> FixedTag for SetOfVec<T>
 where
     T: DerOrd,
@@ -326,7 +369,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T> From<SetOfVec<T>> for Vec<T>
 where
     T: DerOrd,
@@ -337,7 +379,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T> TryFrom<Vec<T>> for SetOfVec<T>
 where
     T: DerOrd,
@@ -345,14 +386,12 @@ where
     type Error = Error;
 
     fn try_from(mut vec: Vec<T>) -> Result<SetOfVec<T>> {
-        // TODO(tarcieri): use `[T]::sort_by` here?
         der_sort(vec.as_mut_slice())?;
         Ok(SetOfVec { inner: vec })
     }
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T, const N: usize> TryFrom<[T; N]> for SetOfVec<T>
 where
     T: DerOrd,
@@ -365,7 +404,6 @@ where
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<T> ValueOrd for SetOfVec<T>
 where
     T: DerOrd,
@@ -375,6 +413,35 @@ where
     }
 }
 
+// Implement by hand because the derive would create invalid values.
+// Use the conversion from Vec to create a valid value.
+#[cfg(feature = "arbitrary")]
+impl<'a, T> arbitrary::Arbitrary<'a> for SetOfVec<T>
+where
+    T: DerOrd + arbitrary::Arbitrary<'a>,
+{
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        Self::try_from(
+            u.arbitrary_iter()?
+                .collect::<std::result::Result<Vec<_>, _>>()?,
+        )
+        .map_err(|_| arbitrary::Error::IncorrectFormat)
+    }
+
+    fn size_hint(_depth: usize) -> (usize, Option<usize>) {
+        (0, None)
+    }
+}
+
+/// Ensure set elements are lexicographically ordered using [`DerOrd`].
+fn check_der_ordering<T: DerOrd>(a: &T, b: &T) -> Result<()> {
+    match a.der_cmp(b)? {
+        Ordering::Less => Ok(()),
+        Ordering::Equal => Err(ErrorKind::SetDuplicate.into()),
+        Ordering::Greater => Err(ErrorKind::SetOrdering.into()),
+    }
+}
+
 /// Sort a mut slice according to its [`DerOrd`], returning any errors which
 /// might occur during the comparison.
 ///
@@ -389,9 +456,15 @@ fn der_sort<T: DerOrd>(slice: &mut [T]) -> Result<()> {
     for i in 0..slice.len() {
         let mut j = i;
 
-        while j > 0 && slice[j - 1].der_cmp(&slice[j])? == Ordering::Greater {
-            slice.swap(j - 1, j);
-            j -= 1;
+        while j > 0 {
+            match slice[j - 1].der_cmp(&slice[j])? {
+                Ordering::Less => break,
+                Ordering::Equal => return Err(ErrorKind::SetDuplicate.into()),
+                Ordering::Greater => {
+                    slice.swap(j - 1, j);
+                    j -= 1;
+                }
+            }
         }
     }
 
@@ -419,22 +492,29 @@ fn validate<T: DerOrd>(slice: &[T]) -> Result<()> {
     Ok(())
 }
 
-#[cfg(all(test, feature = "alloc"))]
+#[cfg(test)]
 mod tests {
-    use super::{SetOf, SetOfVec};
-    use alloc::vec::Vec;
+    use super::SetOf;
+    #[cfg(feature = "alloc")]
+    use super::SetOfVec;
+    use crate::ErrorKind;
 
     #[test]
     fn setof_tryfrom_array() {
         let arr = [3u16, 2, 1, 65535, 0];
         let set = SetOf::try_from(arr).unwrap();
-        assert_eq!(
-            set.iter().cloned().collect::<Vec<u16>>(),
-            &[0, 1, 2, 3, 65535]
-        );
+        assert!(set.iter().copied().eq([0, 1, 2, 3, 65535]));
     }
 
     #[test]
+    fn setof_tryfrom_array_reject_duplicates() {
+        let arr = [1u16, 1];
+        let err = SetOf::try_from(arr).err().unwrap();
+        assert_eq!(err.kind(), ErrorKind::SetDuplicate);
+    }
+
+    #[cfg(feature = "alloc")]
+    #[test]
     fn setofvec_tryfrom_array() {
         let arr = [3u16, 2, 1, 65535, 0];
         let set = SetOfVec::try_from(arr).unwrap();
@@ -448,4 +528,12 @@ mod tests {
         let set = SetOfVec::try_from(vec).unwrap();
         assert_eq!(set.as_ref(), &[0, 1, 2, 3, 65535]);
     }
+
+    #[cfg(feature = "alloc")]
+    #[test]
+    fn setofvec_tryfrom_vec_reject_duplicates() {
+        let vec = vec![1u16, 1];
+        let err = SetOfVec::try_from(vec).err().unwrap();
+        assert_eq!(err.kind(), ErrorKind::SetDuplicate);
+    }
 }
diff --git a/src/asn1/teletex_string.rs b/src/asn1/teletex_string.rs
index 7d6621d..337c071 100644
--- a/src/asn1/teletex_string.rs
+++ b/src/asn1/teletex_string.rs
@@ -1,10 +1,26 @@
 //! ASN.1 `TeletexString` support.
+//!
+use crate::{asn1::AnyRef, FixedTag, Result, StrRef, Tag};
+use core::{fmt, ops::Deref};
+
+macro_rules! impl_teletex_string {
+    ($type: ty) => {
+        impl_teletex_string!($type,);
+    };
+    ($type: ty, $($li: lifetime)?) => {
+        impl_string_type!($type, $($li),*);
+
+        impl<$($li),*> FixedTag for $type {
+            const TAG: Tag = Tag::TeletexString;
+        }
 
-use crate::{
-    asn1::AnyRef, ord::OrdIsValueOrd, ByteSlice, DecodeValue, EncodeValue, Error, FixedTag, Header,
-    Length, Reader, Result, StrSlice, Tag, Writer,
-};
-use core::{fmt, ops::Deref, str};
+        impl<$($li),*> fmt::Debug for $type {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                write!(f, "TeletexString({:?})", self.as_str())
+            }
+        }
+    };
+}
 
 /// ASN.1 `TeletexString` type.
 ///
@@ -25,7 +41,7 @@ use core::{fmt, ops::Deref, str};
 #[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord)]
 pub struct TeletexStringRef<'a> {
     /// Inner value
-    inner: StrSlice<'a>,
+    inner: StrRef<'a>,
 }
 
 impl<'a> TeletexStringRef<'a> {
@@ -41,83 +57,140 @@ impl<'a> TeletexStringRef<'a> {
             return Err(Self::TAG.value_error());
         }
 
-        StrSlice::from_bytes(input)
+        StrRef::from_bytes(input)
             .map(|inner| Self { inner })
             .map_err(|_| Self::TAG.value_error())
     }
 }
 
+impl_teletex_string!(TeletexStringRef<'a>, 'a);
+
 impl<'a> Deref for TeletexStringRef<'a> {
-    type Target = StrSlice<'a>;
+    type Target = StrRef<'a>;
 
     fn deref(&self) -> &Self::Target {
         &self.inner
     }
 }
 
-impl AsRef<str> for TeletexStringRef<'_> {
-    fn as_ref(&self) -> &str {
-        self.as_str()
+impl<'a> From<&TeletexStringRef<'a>> for TeletexStringRef<'a> {
+    fn from(value: &TeletexStringRef<'a>) -> TeletexStringRef<'a> {
+        *value
     }
 }
 
-impl AsRef<[u8]> for TeletexStringRef<'_> {
-    fn as_ref(&self) -> &[u8] {
-        self.as_bytes()
+impl<'a> From<TeletexStringRef<'a>> for AnyRef<'a> {
+    fn from(teletex_string: TeletexStringRef<'a>) -> AnyRef<'a> {
+        AnyRef::from_tag_and_value(Tag::TeletexString, teletex_string.inner.into())
     }
 }
 
-impl<'a> DecodeValue<'a> for TeletexStringRef<'a> {
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        Self::new(ByteSlice::decode_value(reader, header)?.as_slice())
-    }
-}
+#[cfg(feature = "alloc")]
+pub use self::allocation::TeletexString;
 
-impl<'a> EncodeValue for TeletexStringRef<'a> {
-    fn value_len(&self) -> Result<Length> {
-        self.inner.value_len()
+#[cfg(feature = "alloc")]
+mod allocation {
+    use super::TeletexStringRef;
+
+    use crate::{
+        asn1::AnyRef,
+        referenced::{OwnedToRef, RefToOwned},
+        BytesRef, Error, FixedTag, Result, StrOwned, Tag,
+    };
+    use alloc::string::String;
+    use core::{fmt, ops::Deref};
+
+    /// ASN.1 `TeletexString` type.
+    ///
+    /// Supports a subset the ASCII character set (described below).
+    ///
+    /// For UTF-8, use [`Utf8StringRef`][`crate::asn1::Utf8StringRef`] instead.
+    /// For the full ASCII character set, use
+    /// [`Ia5StringRef`][`crate::asn1::Ia5StringRef`].
+    ///
+    /// # Supported characters
+    ///
+    /// The standard defines a complex character set allowed in this type. However, quoting the ASN.1
+    /// mailing list, "a sizable volume of software in the world treats TeletexString (T61String) as a
+    /// simple 8-bit string with mostly Windows Latin 1 (superset of iso-8859-1) encoding".
+    ///
+    #[derive(Clone, Eq, PartialEq, PartialOrd, Ord)]
+    pub struct TeletexString {
+        /// Inner value
+        inner: StrOwned,
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        self.inner.encode_value(writer)
+    impl TeletexString {
+        /// Create a new ASN.1 `TeletexString`.
+        pub fn new<T>(input: &T) -> Result<Self>
+        where
+            T: AsRef<[u8]> + ?Sized,
+        {
+            let input = input.as_ref();
+
+            TeletexStringRef::new(input)?;
+
+            StrOwned::from_bytes(input)
+                .map(|inner| Self { inner })
+                .map_err(|_| Self::TAG.value_error())
+        }
     }
-}
 
-impl FixedTag for TeletexStringRef<'_> {
-    const TAG: Tag = Tag::TeletexString;
-}
+    impl_teletex_string!(TeletexString);
 
-impl OrdIsValueOrd for TeletexStringRef<'_> {}
+    impl Deref for TeletexString {
+        type Target = StrOwned;
 
-impl<'a> From<&TeletexStringRef<'a>> for TeletexStringRef<'a> {
-    fn from(value: &TeletexStringRef<'a>) -> TeletexStringRef<'a> {
-        *value
+        fn deref(&self) -> &Self::Target {
+            &self.inner
+        }
     }
-}
 
-impl<'a> TryFrom<AnyRef<'a>> for TeletexStringRef<'a> {
-    type Error = Error;
+    impl<'a> From<TeletexStringRef<'a>> for TeletexString {
+        fn from(value: TeletexStringRef<'a>) -> TeletexString {
+            let inner =
+                StrOwned::from_bytes(value.inner.as_bytes()).expect("Invalid TeletexString");
+            Self { inner }
+        }
+    }
 
-    fn try_from(any: AnyRef<'a>) -> Result<TeletexStringRef<'a>> {
-        any.decode_into()
+    impl<'a> From<&'a TeletexString> for AnyRef<'a> {
+        fn from(teletex_string: &'a TeletexString) -> AnyRef<'a> {
+            AnyRef::from_tag_and_value(
+                Tag::TeletexString,
+                BytesRef::new(teletex_string.inner.as_bytes()).expect("Invalid TeletexString"),
+            )
+        }
     }
-}
 
-impl<'a> From<TeletexStringRef<'a>> for AnyRef<'a> {
-    fn from(teletex_string: TeletexStringRef<'a>) -> AnyRef<'a> {
-        AnyRef::from_tag_and_value(Tag::TeletexString, teletex_string.inner.into())
+    impl<'a> RefToOwned<'a> for TeletexStringRef<'a> {
+        type Owned = TeletexString;
+        fn ref_to_owned(&self) -> Self::Owned {
+            TeletexString {
+                inner: self.inner.ref_to_owned(),
+            }
+        }
     }
-}
 
-impl<'a> fmt::Display for TeletexStringRef<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(self.as_str())
+    impl OwnedToRef for TeletexString {
+        type Borrowed<'a> = TeletexStringRef<'a>;
+        fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+            TeletexStringRef {
+                inner: self.inner.owned_to_ref(),
+            }
+        }
     }
-}
 
-impl<'a> fmt::Debug for TeletexStringRef<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "TeletexString({:?})", self.as_str())
+    impl TryFrom<String> for TeletexString {
+        type Error = Error;
+
+        fn try_from(input: String) -> Result<Self> {
+            TeletexStringRef::new(&input)?;
+
+            StrOwned::new(input)
+                .map(|inner| Self { inner })
+                .map_err(|_| Self::TAG.value_error())
+        }
     }
 }
 
diff --git a/src/asn1/utc_time.rs b/src/asn1/utc_time.rs
index 7c23811..9f2f171 100644
--- a/src/asn1/utc_time.rs
+++ b/src/asn1/utc_time.rs
@@ -1,7 +1,6 @@
 //! ASN.1 `UTCTime` support.
 
 use crate::{
-    asn1::AnyRef,
     datetime::{self, DateTime},
     ord::OrdIsValueOrd,
     DecodeValue, EncodeValue, Error, ErrorKind, FixedTag, Header, Length, Reader, Result, Tag,
@@ -12,9 +11,6 @@ use core::time::Duration;
 #[cfg(feature = "std")]
 use std::time::SystemTime;
 
-/// Maximum year that can be represented as a `UTCTime`.
-pub const MAX_YEAR: u16 = 2049;
-
 /// ASN.1 `UTCTime` type.
 ///
 /// This type implements the validity requirements specified in
@@ -29,6 +25,9 @@ pub const MAX_YEAR: u16 = 2049;
 /// >   interpreted as `19YY`; and
 /// > - Where `YY` is less than 50, the year SHALL be interpreted as `20YY`.
 ///
+/// Note: Due to common operations working on `UNIX_EPOCH` [`UtcTime`]s are
+/// only supported for the years 1970-2049.
+///
 /// [1]: https://tools.ietf.org/html/rfc5280#section-4.1.2.5.1
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 pub struct UtcTime(DateTime);
@@ -37,9 +36,12 @@ impl UtcTime {
     /// Length of an RFC 5280-flavored ASN.1 DER-encoded [`UtcTime`].
     pub const LENGTH: usize = 13;
 
+    /// Maximum year that can be represented as a `UTCTime`.
+    pub const MAX_YEAR: u16 = 2049;
+
     /// Create a [`UtcTime`] from a [`DateTime`].
     pub fn from_date_time(datetime: DateTime) -> Result<Self> {
-        if datetime.year() <= MAX_YEAR {
+        if datetime.year() <= UtcTime::MAX_YEAR {
             Ok(Self(datetime))
         } else {
             Err(Self::TAG.value_error())
@@ -64,7 +66,6 @@ impl UtcTime {
 
     /// Instantiate from [`SystemTime`].
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn from_system_time(time: SystemTime) -> Result<Self> {
         DateTime::try_from(time)
             .map_err(|_| Self::TAG.value_error())?
@@ -73,12 +74,13 @@ impl UtcTime {
 
     /// Convert to [`SystemTime`].
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn to_system_time(&self) -> SystemTime {
         self.0.to_system_time()
     }
 }
 
+impl_any_conversions!(UtcTime);
+
 impl<'a> DecodeValue<'a> for UtcTime {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         if Self::LENGTH != usize::try_from(header.length)? {
@@ -120,7 +122,7 @@ impl EncodeValue for UtcTime {
         Self::LENGTH.try_into()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         let year = match self.0.year() {
             y @ 1950..=1999 => y.checked_sub(1900),
             y @ 2000..=2049 => y.checked_sub(2000),
@@ -180,18 +182,43 @@ impl TryFrom<&DateTime> for UtcTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl From<UtcTime> for SystemTime {
     fn from(utc_time: UtcTime) -> SystemTime {
         utc_time.to_system_time()
     }
 }
 
-impl TryFrom<AnyRef<'_>> for UtcTime {
-    type Error = Error;
-
-    fn try_from(any: AnyRef<'_>) -> Result<UtcTime> {
-        any.decode_into()
+// Implement by hand because the derive would create invalid values.
+// Use the conversion from DateTime to create a valid value.
+// The DateTime type has a way bigger range of valid years than UtcTime,
+// so the DateTime year is mapped into a valid range to throw away less inputs.
+#[cfg(feature = "arbitrary")]
+impl<'a> arbitrary::Arbitrary<'a> for UtcTime {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        const MIN_YEAR: u16 = 1970;
+        const VALID_YEAR_COUNT: u16 = UtcTime::MAX_YEAR - MIN_YEAR + 1;
+        const AVERAGE_SECONDS_IN_YEAR: u64 = 31_556_952;
+
+        let datetime = DateTime::arbitrary(u)?;
+        let year = datetime.year();
+        let duration = datetime.unix_duration();
+
+        // Clamp the year into a valid range to not throw away too much input
+        let valid_year = (year.saturating_sub(MIN_YEAR))
+            .rem_euclid(VALID_YEAR_COUNT)
+            .saturating_add(MIN_YEAR);
+        let year_to_remove = year.saturating_sub(valid_year);
+        let valid_duration = duration
+            - Duration::from_secs(
+                u64::from(year_to_remove).saturating_mul(AVERAGE_SECONDS_IN_YEAR),
+            );
+
+        Self::from_date_time(DateTime::from_unix_duration(valid_duration).expect("supported range"))
+            .map_err(|_| arbitrary::Error::IncorrectFormat)
+    }
+
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        DateTime::size_hint(depth)
     }
 }
 
diff --git a/src/asn1/utf8_string.rs b/src/asn1/utf8_string.rs
index 1a06411..6018750 100644
--- a/src/asn1/utf8_string.rs
+++ b/src/asn1/utf8_string.rs
@@ -1,13 +1,16 @@
 //! ASN.1 `UTF8String` support.
 
 use crate::{
-    asn1::AnyRef, ord::OrdIsValueOrd, ByteSlice, DecodeValue, EncodeValue, Error, FixedTag, Header,
-    Length, Reader, Result, StrSlice, Tag, Writer,
+    asn1::AnyRef, ord::OrdIsValueOrd, EncodeValue, Error, FixedTag, Length, Result, StrRef, Tag,
+    Writer,
 };
 use core::{fmt, ops::Deref, str};
 
 #[cfg(feature = "alloc")]
-use alloc::{borrow::ToOwned, string::String};
+use {
+    crate::{DecodeValue, Header, Reader},
+    alloc::{borrow::ToOwned, string::String},
+};
 
 /// ASN.1 `UTF8String` type.
 ///
@@ -26,7 +29,7 @@ use alloc::{borrow::ToOwned, string::String};
 #[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord)]
 pub struct Utf8StringRef<'a> {
     /// Inner value
-    inner: StrSlice<'a>,
+    inner: StrRef<'a>,
 }
 
 impl<'a> Utf8StringRef<'a> {
@@ -35,75 +38,33 @@ impl<'a> Utf8StringRef<'a> {
     where
         T: AsRef<[u8]> + ?Sized,
     {
-        StrSlice::from_bytes(input.as_ref()).map(|inner| Self { inner })
+        StrRef::from_bytes(input.as_ref()).map(|inner| Self { inner })
     }
 }
 
+impl_string_type!(Utf8StringRef<'a>, 'a);
+
 impl<'a> Deref for Utf8StringRef<'a> {
-    type Target = StrSlice<'a>;
+    type Target = StrRef<'a>;
 
     fn deref(&self) -> &Self::Target {
         &self.inner
     }
 }
 
-impl AsRef<str> for Utf8StringRef<'_> {
-    fn as_ref(&self) -> &str {
-        self.as_str()
-    }
-}
-
-impl AsRef<[u8]> for Utf8StringRef<'_> {
-    fn as_ref(&self) -> &[u8] {
-        self.as_bytes()
-    }
-}
-
-impl<'a> DecodeValue<'a> for Utf8StringRef<'a> {
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        Self::new(ByteSlice::decode_value(reader, header)?.as_slice())
-    }
-}
-
-impl EncodeValue for Utf8StringRef<'_> {
-    fn value_len(&self) -> Result<Length> {
-        self.inner.value_len()
-    }
-
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        self.inner.encode_value(writer)
-    }
-}
-
 impl FixedTag for Utf8StringRef<'_> {
     const TAG: Tag = Tag::Utf8String;
 }
 
-impl OrdIsValueOrd for Utf8StringRef<'_> {}
-
 impl<'a> From<&Utf8StringRef<'a>> for Utf8StringRef<'a> {
     fn from(value: &Utf8StringRef<'a>) -> Utf8StringRef<'a> {
         *value
     }
 }
 
-impl<'a> TryFrom<AnyRef<'a>> for Utf8StringRef<'a> {
-    type Error = Error;
-
-    fn try_from(any: AnyRef<'a>) -> Result<Utf8StringRef<'a>> {
-        any.decode_into()
-    }
-}
-
 impl<'a> From<Utf8StringRef<'a>> for AnyRef<'a> {
-    fn from(printable_string: Utf8StringRef<'a>) -> AnyRef<'a> {
-        AnyRef::from_tag_and_value(Tag::Utf8String, printable_string.inner.into())
-    }
-}
-
-impl<'a> fmt::Display for Utf8StringRef<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(self.as_str())
+    fn from(utf_string: Utf8StringRef<'a>) -> AnyRef<'a> {
+        AnyRef::from_tag_and_value(Tag::Utf8String, utf_string.inner.into())
     }
 }
 
@@ -126,7 +87,7 @@ impl EncodeValue for str {
         Utf8StringRef::new(self)?.value_len()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         Utf8StringRef::new(self)?.encode_value(writer)
     }
 }
@@ -138,7 +99,6 @@ impl FixedTag for str {
 impl OrdIsValueOrd for str {}
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<'a> From<Utf8StringRef<'a>> for String {
     fn from(s: Utf8StringRef<'a>) -> String {
         s.as_str().to_owned()
@@ -146,7 +106,6 @@ impl<'a> From<Utf8StringRef<'a>> for String {
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<'a> TryFrom<AnyRef<'a>> for String {
     type Error = Error;
 
@@ -156,7 +115,6 @@ impl<'a> TryFrom<AnyRef<'a>> for String {
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl<'a> DecodeValue<'a> for String {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
         Ok(String::from_utf8(reader.read_vec(header.length)?)?)
@@ -164,25 +122,22 @@ impl<'a> DecodeValue<'a> for String {
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl EncodeValue for String {
     fn value_len(&self) -> Result<Length> {
         Utf8StringRef::new(self)?.value_len()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         Utf8StringRef::new(self)?.encode_value(writer)
     }
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl FixedTag for String {
     const TAG: Tag = Tag::Utf8String;
 }
 
 #[cfg(feature = "alloc")]
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 impl OrdIsValueOrd for String {}
 
 #[cfg(test)]
diff --git a/src/asn1/videotex_string.rs b/src/asn1/videotex_string.rs
index b758a22..55b1a49 100644
--- a/src/asn1/videotex_string.rs
+++ b/src/asn1/videotex_string.rs
@@ -1,10 +1,7 @@
 //! ASN.1 `VideotexString` support.
 
-use crate::{
-    asn1::AnyRef, ord::OrdIsValueOrd, ByteSlice, DecodeValue, EncodeValue, Error, FixedTag, Header,
-    Length, Reader, Result, StrSlice, Tag, Writer,
-};
-use core::{fmt, ops::Deref, str};
+use crate::{asn1::AnyRef, FixedTag, Result, StrRef, Tag};
+use core::{fmt, ops::Deref};
 
 /// ASN.1 `VideotexString` type.
 ///
@@ -23,7 +20,7 @@ use core::{fmt, ops::Deref, str};
 #[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord)]
 pub struct VideotexStringRef<'a> {
     /// Inner value
-    inner: StrSlice<'a>,
+    inner: StrRef<'a>,
 }
 
 impl<'a> VideotexStringRef<'a> {
@@ -40,68 +37,32 @@ impl<'a> VideotexStringRef<'a> {
             return Err(Self::TAG.value_error());
         }
 
-        StrSlice::from_bytes(input)
+        StrRef::from_bytes(input)
             .map(|inner| Self { inner })
             .map_err(|_| Self::TAG.value_error())
     }
 }
 
+impl_string_type!(VideotexStringRef<'a>, 'a);
+
 impl<'a> Deref for VideotexStringRef<'a> {
-    type Target = StrSlice<'a>;
+    type Target = StrRef<'a>;
 
     fn deref(&self) -> &Self::Target {
         &self.inner
     }
 }
 
-impl AsRef<str> for VideotexStringRef<'_> {
-    fn as_ref(&self) -> &str {
-        self.as_str()
-    }
-}
-
-impl AsRef<[u8]> for VideotexStringRef<'_> {
-    fn as_ref(&self) -> &[u8] {
-        self.as_bytes()
-    }
-}
-
-impl<'a> DecodeValue<'a> for VideotexStringRef<'a> {
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        Self::new(ByteSlice::decode_value(reader, header)?.as_slice())
-    }
-}
-
-impl<'a> EncodeValue for VideotexStringRef<'a> {
-    fn value_len(&self) -> Result<Length> {
-        self.inner.value_len()
-    }
-
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        self.inner.encode_value(writer)
-    }
-}
-
 impl FixedTag for VideotexStringRef<'_> {
     const TAG: Tag = Tag::VideotexString;
 }
 
-impl OrdIsValueOrd for VideotexStringRef<'_> {}
-
 impl<'a> From<&VideotexStringRef<'a>> for VideotexStringRef<'a> {
     fn from(value: &VideotexStringRef<'a>) -> VideotexStringRef<'a> {
         *value
     }
 }
 
-impl<'a> TryFrom<AnyRef<'a>> for VideotexStringRef<'a> {
-    type Error = Error;
-
-    fn try_from(any: AnyRef<'a>) -> Result<VideotexStringRef<'a>> {
-        any.decode_into()
-    }
-}
-
 impl<'a> From<VideotexStringRef<'a>> for AnyRef<'a> {
     fn from(printable_string: VideotexStringRef<'a>) -> AnyRef<'a> {
         AnyRef::from_tag_and_value(Tag::VideotexString, printable_string.inner.into())
@@ -114,12 +75,6 @@ impl<'a> From<VideotexStringRef<'a>> for &'a [u8] {
     }
 }
 
-impl<'a> fmt::Display for VideotexStringRef<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str(self.as_str())
-    }
-}
-
 impl<'a> fmt::Debug for VideotexStringRef<'a> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "VideotexString({:?})", self.as_str())
diff --git a/src/byte_slice.rs b/src/byte_slice.rs
deleted file mode 100644
index 00d46d0..0000000
--- a/src/byte_slice.rs
+++ /dev/null
@@ -1,116 +0,0 @@
-//! Common handling for types backed by byte slices with enforcement of a
-//! library-level length limitation i.e. `Length::max()`.
-
-use crate::{
-    str_slice::StrSlice, DecodeValue, DerOrd, EncodeValue, Error, Header, Length, Reader, Result,
-    Writer,
-};
-use core::cmp::Ordering;
-
-/// Byte slice newtype which respects the `Length::max()` limit.
-#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
-pub(crate) struct ByteSlice<'a> {
-    /// Precomputed `Length` (avoids possible panicking conversions)
-    length: Length,
-
-    /// Inner value
-    inner: &'a [u8],
-}
-
-impl<'a> ByteSlice<'a> {
-    /// Constant value representing an empty byte slice.
-    pub const EMPTY: Self = Self {
-        length: Length::ZERO,
-        inner: &[],
-    };
-
-    /// Create a new [`ByteSlice`], ensuring that the provided `slice` value
-    /// is shorter than `Length::max()`.
-    pub fn new(slice: &'a [u8]) -> Result<Self> {
-        Ok(Self {
-            length: Length::try_from(slice.len())?,
-            inner: slice,
-        })
-    }
-
-    /// Borrow the inner byte slice
-    pub fn as_slice(&self) -> &'a [u8] {
-        self.inner
-    }
-
-    /// Get the [`Length`] of this [`ByteSlice`]
-    pub fn len(self) -> Length {
-        self.length
-    }
-
-    /// Is this [`ByteSlice`] empty?
-    pub fn is_empty(self) -> bool {
-        self.len() == Length::ZERO
-    }
-}
-
-impl AsRef<[u8]> for ByteSlice<'_> {
-    fn as_ref(&self) -> &[u8] {
-        self.as_slice()
-    }
-}
-
-impl<'a> DecodeValue<'a> for ByteSlice<'a> {
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        reader.read_slice(header.length).and_then(Self::new)
-    }
-}
-
-impl EncodeValue for ByteSlice<'_> {
-    fn value_len(&self) -> Result<Length> {
-        Ok(self.length)
-    }
-
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
-        writer.write(self.as_ref())
-    }
-}
-
-impl Default for ByteSlice<'_> {
-    fn default() -> Self {
-        Self {
-            length: Length::ZERO,
-            inner: &[],
-        }
-    }
-}
-
-impl DerOrd for ByteSlice<'_> {
-    fn der_cmp(&self, other: &Self) -> Result<Ordering> {
-        Ok(self.as_slice().cmp(other.as_slice()))
-    }
-}
-
-impl<'a> From<&'a [u8; 1]> for ByteSlice<'a> {
-    fn from(byte: &'a [u8; 1]) -> ByteSlice<'a> {
-        Self {
-            length: Length::ONE,
-            inner: byte,
-        }
-    }
-}
-
-impl<'a> From<StrSlice<'a>> for ByteSlice<'a> {
-    fn from(s: StrSlice<'a>) -> ByteSlice<'a> {
-        let bytes = s.as_bytes();
-        debug_assert_eq!(bytes.len(), usize::try_from(s.length).expect("overflow"));
-
-        ByteSlice {
-            inner: bytes,
-            length: s.length,
-        }
-    }
-}
-
-impl<'a> TryFrom<&'a [u8]> for ByteSlice<'a> {
-    type Error = Error;
-
-    fn try_from(slice: &'a [u8]) -> Result<Self> {
-        Self::new(slice)
-    }
-}
diff --git a/src/bytes_owned.rs b/src/bytes_owned.rs
new file mode 100644
index 0000000..b5e928e
--- /dev/null
+++ b/src/bytes_owned.rs
@@ -0,0 +1,162 @@
+//! Common handling for types backed by byte allocation with enforcement of a
+//! library-level length limitation i.e. `Length::max()`.
+
+use crate::{
+    referenced::OwnedToRef, BytesRef, DecodeValue, DerOrd, EncodeValue, Error, Header, Length,
+    Reader, Result, StrRef, Writer,
+};
+use alloc::{boxed::Box, vec::Vec};
+use core::cmp::Ordering;
+
+/// Byte slice newtype which respects the `Length::max()` limit.
+#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+pub(crate) struct BytesOwned {
+    /// Precomputed `Length` (avoids possible panicking conversions)
+    length: Length,
+
+    /// Inner value
+    inner: Box<[u8]>,
+}
+
+impl BytesOwned {
+    /// Create a new [`BytesOwned`], ensuring that the provided `slice` value
+    /// is shorter than `Length::max()`.
+    pub fn new(data: impl Into<Box<[u8]>>) -> Result<Self> {
+        let inner: Box<[u8]> = data.into();
+
+        Ok(Self {
+            length: Length::try_from(inner.len())?,
+            inner,
+        })
+    }
+
+    /// Borrow the inner byte slice
+    pub fn as_slice(&self) -> &[u8] {
+        &self.inner
+    }
+
+    /// Get the [`Length`] of this [`BytesRef`]
+    pub fn len(&self) -> Length {
+        self.length
+    }
+
+    /// Is this [`BytesOwned`] empty?
+    pub fn is_empty(&self) -> bool {
+        self.len() == Length::ZERO
+    }
+}
+
+impl AsRef<[u8]> for BytesOwned {
+    fn as_ref(&self) -> &[u8] {
+        self.as_slice()
+    }
+}
+
+impl<'a> DecodeValue<'a> for BytesOwned {
+    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+        reader.read_vec(header.length).and_then(Self::new)
+    }
+}
+
+impl EncodeValue for BytesOwned {
+    fn value_len(&self) -> Result<Length> {
+        Ok(self.length)
+    }
+
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+        writer.write(self.as_ref())
+    }
+}
+
+impl Default for BytesOwned {
+    fn default() -> Self {
+        Self {
+            length: Length::ZERO,
+            inner: Box::new([]),
+        }
+    }
+}
+
+impl DerOrd for BytesOwned {
+    fn der_cmp(&self, other: &Self) -> Result<Ordering> {
+        Ok(self.as_slice().cmp(other.as_slice()))
+    }
+}
+
+impl From<BytesOwned> for Box<[u8]> {
+    fn from(bytes: BytesOwned) -> Box<[u8]> {
+        bytes.inner
+    }
+}
+
+impl From<StrRef<'_>> for BytesOwned {
+    fn from(s: StrRef<'_>) -> BytesOwned {
+        let bytes = s.as_bytes();
+        debug_assert_eq!(bytes.len(), usize::try_from(s.length).expect("overflow"));
+
+        BytesOwned {
+            inner: Box::from(bytes),
+            length: s.length,
+        }
+    }
+}
+
+impl OwnedToRef for BytesOwned {
+    type Borrowed<'a> = BytesRef<'a>;
+    fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+        BytesRef {
+            length: self.length,
+            inner: self.inner.as_ref(),
+        }
+    }
+}
+
+impl From<BytesRef<'_>> for BytesOwned {
+    fn from(s: BytesRef<'_>) -> BytesOwned {
+        BytesOwned {
+            length: s.length,
+            inner: Box::from(s.inner),
+        }
+    }
+}
+
+impl TryFrom<&[u8]> for BytesOwned {
+    type Error = Error;
+
+    fn try_from(bytes: &[u8]) -> Result<Self> {
+        Self::new(bytes)
+    }
+}
+
+impl TryFrom<Box<[u8]>> for BytesOwned {
+    type Error = Error;
+
+    fn try_from(bytes: Box<[u8]>) -> Result<Self> {
+        Self::new(bytes)
+    }
+}
+
+impl TryFrom<Vec<u8>> for BytesOwned {
+    type Error = Error;
+
+    fn try_from(bytes: Vec<u8>) -> Result<Self> {
+        Self::new(bytes)
+    }
+}
+
+// Implement by hand because the derive would create invalid values.
+// Make sure the length and the inner.len matches.
+#[cfg(feature = "arbitrary")]
+impl<'a> arbitrary::Arbitrary<'a> for BytesOwned {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        let length = u.arbitrary()?;
+        Ok(Self {
+            length,
+            inner: Box::from(u.bytes(u32::from(length) as usize)?),
+        })
+    }
+
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        arbitrary::size_hint::and(Length::size_hint(depth), (0, None))
+    }
+}
diff --git a/src/bytes_ref.rs b/src/bytes_ref.rs
new file mode 100644
index 0000000..2cee407
--- /dev/null
+++ b/src/bytes_ref.rs
@@ -0,0 +1,152 @@
+//! Common handling for types backed by byte slices with enforcement of a
+//! library-level length limitation i.e. `Length::max()`.
+
+use crate::{
+    DecodeValue, DerOrd, EncodeValue, Error, Header, Length, Reader, Result, StrRef, Writer,
+};
+use core::cmp::Ordering;
+
+#[cfg(feature = "alloc")]
+use crate::StrOwned;
+
+/// Byte slice newtype which respects the `Length::max()` limit.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+pub(crate) struct BytesRef<'a> {
+    /// Precomputed `Length` (avoids possible panicking conversions)
+    pub length: Length,
+
+    /// Inner value
+    pub inner: &'a [u8],
+}
+
+impl<'a> BytesRef<'a> {
+    /// Constant value representing an empty byte slice.
+    pub const EMPTY: Self = Self {
+        length: Length::ZERO,
+        inner: &[],
+    };
+
+    /// Create a new [`BytesRef`], ensuring that the provided `slice` value
+    /// is shorter than `Length::max()`.
+    pub fn new(slice: &'a [u8]) -> Result<Self> {
+        Ok(Self {
+            length: Length::try_from(slice.len())?,
+            inner: slice,
+        })
+    }
+
+    /// Borrow the inner byte slice
+    pub fn as_slice(&self) -> &'a [u8] {
+        self.inner
+    }
+
+    /// Get the [`Length`] of this [`BytesRef`]
+    pub fn len(self) -> Length {
+        self.length
+    }
+
+    /// Is this [`BytesRef`] empty?
+    pub fn is_empty(self) -> bool {
+        self.len() == Length::ZERO
+    }
+}
+
+impl AsRef<[u8]> for BytesRef<'_> {
+    fn as_ref(&self) -> &[u8] {
+        self.as_slice()
+    }
+}
+
+impl<'a> DecodeValue<'a> for BytesRef<'a> {
+    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+        reader.read_slice(header.length).and_then(Self::new)
+    }
+}
+
+impl EncodeValue for BytesRef<'_> {
+    fn value_len(&self) -> Result<Length> {
+        Ok(self.length)
+    }
+
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+        writer.write(self.as_ref())
+    }
+}
+
+impl Default for BytesRef<'_> {
+    fn default() -> Self {
+        Self {
+            length: Length::ZERO,
+            inner: &[],
+        }
+    }
+}
+
+impl DerOrd for BytesRef<'_> {
+    fn der_cmp(&self, other: &Self) -> Result<Ordering> {
+        Ok(self.as_slice().cmp(other.as_slice()))
+    }
+}
+
+impl<'a> From<StrRef<'a>> for BytesRef<'a> {
+    fn from(s: StrRef<'a>) -> BytesRef<'a> {
+        let bytes = s.as_bytes();
+        debug_assert_eq!(bytes.len(), usize::try_from(s.length).expect("overflow"));
+
+        BytesRef {
+            inner: bytes,
+            length: s.length,
+        }
+    }
+}
+
+#[cfg(feature = "alloc")]
+impl<'a> From<&'a StrOwned> for BytesRef<'a> {
+    fn from(s: &'a StrOwned) -> BytesRef<'a> {
+        let bytes = s.as_bytes();
+        debug_assert_eq!(bytes.len(), usize::try_from(s.length).expect("overflow"));
+
+        BytesRef {
+            inner: bytes,
+            length: s.length,
+        }
+    }
+}
+
+impl<'a> TryFrom<&'a [u8]> for BytesRef<'a> {
+    type Error = Error;
+
+    fn try_from(slice: &'a [u8]) -> Result<Self> {
+        Self::new(slice)
+    }
+}
+
+// Implement by hand because the derive would create invalid values.
+// Make sure the length and the inner.len matches.
+#[cfg(feature = "arbitrary")]
+impl<'a> arbitrary::Arbitrary<'a> for BytesRef<'a> {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        let length = u.arbitrary()?;
+        Ok(Self {
+            length,
+            inner: u.bytes(u32::from(length) as usize)?,
+        })
+    }
+
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        arbitrary::size_hint::and(Length::size_hint(depth), (0, None))
+    }
+}
+
+#[cfg(feature = "alloc")]
+mod allocating {
+    use super::BytesRef;
+    use crate::{referenced::RefToOwned, BytesOwned};
+
+    impl<'a> RefToOwned<'a> for BytesRef<'a> {
+        type Owned = BytesOwned;
+        fn ref_to_owned(&self) -> Self::Owned {
+            BytesOwned::from(*self)
+        }
+    }
+}
diff --git a/src/datetime.rs b/src/datetime.rs
index 2b4c504..fd09b68 100644
--- a/src/datetime.rs
+++ b/src/datetime.rs
@@ -56,6 +56,18 @@ pub struct DateTime {
 }
 
 impl DateTime {
+    /// This is the maximum date represented by the [`DateTime`]
+    /// This corresponds to: 9999-12-31T23:59:59Z
+    pub const INFINITY: DateTime = DateTime {
+        year: 9999,
+        month: 12,
+        day: 31,
+        hour: 23,
+        minutes: 59,
+        seconds: 59,
+        unix_duration: MAX_UNIX_DURATION,
+    };
+
     /// Create a new [`DateTime`] from the given UTC time components.
     // TODO(tarcieri): checked arithmetic
     #[allow(clippy::integer_arithmetic)]
@@ -240,7 +252,6 @@ impl DateTime {
 
     /// Instantiate from [`SystemTime`].
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn from_system_time(time: SystemTime) -> Result<Self> {
         time.duration_since(UNIX_EPOCH)
             .map_err(|_| ErrorKind::DateTime.into())
@@ -249,7 +260,6 @@ impl DateTime {
 
     /// Convert to [`SystemTime`].
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn to_system_time(&self) -> SystemTime {
         UNIX_EPOCH + self.unix_duration()
     }
@@ -258,19 +268,12 @@ impl DateTime {
 impl FromStr for DateTime {
     type Err = Error;
 
-    // TODO(tarcieri): checked arithmetic
-    #[allow(clippy::integer_arithmetic)]
     fn from_str(s: &str) -> Result<Self> {
         match *s.as_bytes() {
             [year1, year2, year3, year4, b'-', month1, month2, b'-', day1, day2, b'T', hour1, hour2, b':', min1, min2, b':', sec1, sec2, b'Z'] =>
             {
                 let tag = Tag::GeneralizedTime;
-                let year =
-                    u16::from(decode_decimal(tag, year1, year2).map_err(|_| ErrorKind::DateTime)?)
-                        * 100
-                        + u16::from(
-                            decode_decimal(tag, year3, year4).map_err(|_| ErrorKind::DateTime)?,
-                        );
+                let year = decode_year(&[year1, year2, year3, year4])?;
                 let month = decode_decimal(tag, month1, month2).map_err(|_| ErrorKind::DateTime)?;
                 let day = decode_decimal(tag, day1, day2).map_err(|_| ErrorKind::DateTime)?;
                 let hour = decode_decimal(tag, hour1, hour2).map_err(|_| ErrorKind::DateTime)?;
@@ -294,7 +297,6 @@ impl fmt::Display for DateTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl From<DateTime> for SystemTime {
     fn from(time: DateTime) -> SystemTime {
         time.to_system_time()
@@ -302,7 +304,6 @@ impl From<DateTime> for SystemTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl From<&DateTime> for SystemTime {
     fn from(time: &DateTime) -> SystemTime {
         time.to_system_time()
@@ -310,7 +311,6 @@ impl From<&DateTime> for SystemTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl TryFrom<SystemTime> for DateTime {
     type Error = Error;
 
@@ -320,7 +320,6 @@ impl TryFrom<SystemTime> for DateTime {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl TryFrom<&SystemTime> for DateTime {
     type Error = Error;
 
@@ -330,12 +329,11 @@ impl TryFrom<&SystemTime> for DateTime {
 }
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 impl TryFrom<DateTime> for PrimitiveDateTime {
     type Error = Error;
 
     fn try_from(time: DateTime) -> Result<PrimitiveDateTime> {
-        let month = (time.month() as u8).try_into()?;
+        let month = time.month().try_into()?;
         let date = time::Date::from_calendar_date(i32::from(time.year()), month, time.day())?;
         let time = time::Time::from_hms(time.hour(), time.minutes(), time.seconds())?;
 
@@ -344,7 +342,6 @@ impl TryFrom<DateTime> for PrimitiveDateTime {
 }
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 impl TryFrom<PrimitiveDateTime> for DateTime {
     type Error = Error;
 
@@ -360,11 +357,28 @@ impl TryFrom<PrimitiveDateTime> for DateTime {
     }
 }
 
+// Implement by hand because the derive would create invalid values.
+// Use the conversion from Duration to create a valid value.
+#[cfg(feature = "arbitrary")]
+impl<'a> arbitrary::Arbitrary<'a> for DateTime {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        Self::from_unix_duration(Duration::new(
+            u.int_in_range(0..=MAX_UNIX_DURATION.as_secs().saturating_sub(1))?,
+            u.int_in_range(0..=999_999_999)?,
+        ))
+        .map_err(|_| arbitrary::Error::IncorrectFormat)
+    }
+
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        arbitrary::size_hint::and(u64::size_hint(depth), u32::size_hint(depth))
+    }
+}
+
 /// Decode 2-digit decimal value
 // TODO(tarcieri): checked arithmetic
 #[allow(clippy::integer_arithmetic)]
 pub(crate) fn decode_decimal(tag: Tag, hi: u8, lo: u8) -> Result<u8> {
-    if (b'0'..=b'9').contains(&hi) && (b'0'..=b'9').contains(&lo) {
+    if hi.is_ascii_digit() && lo.is_ascii_digit() {
         Ok((hi - b'0') * 10 + (lo - b'0'))
     } else {
         Err(tag.value_error())
@@ -386,6 +400,16 @@ where
     writer.write_byte(b'0'.checked_add(value % 10).ok_or(ErrorKind::Overflow)?)
 }
 
+/// Decode 4-digit year.
+// TODO(tarcieri): checked arithmetic
+#[allow(clippy::integer_arithmetic)]
+fn decode_year(year: &[u8; 4]) -> Result<u16> {
+    let tag = Tag::GeneralizedTime;
+    let hi = decode_decimal(tag, year[0], year[1]).map_err(|_| ErrorKind::DateTime)?;
+    let lo = decode_decimal(tag, year[2], year[3]).map_err(|_| ErrorKind::DateTime)?;
+    Ok(u16::from(hi) * 100 + u16::from(lo))
+}
+
 #[cfg(test)]
 mod tests {
     use super::DateTime;
diff --git a/src/decode.rs b/src/decode.rs
index 1c63b32..fe53341 100644
--- a/src/decode.rs
+++ b/src/decode.rs
@@ -1,6 +1,7 @@
 //! Trait definition for [`Decode`].
 
 use crate::{FixedTag, Header, Reader, Result, SliceReader};
+use core::marker::PhantomData;
 
 #[cfg(feature = "pem")]
 use crate::{pem::PemLabel, PemReader};
@@ -8,6 +9,9 @@ use crate::{pem::PemLabel, PemReader};
 #[cfg(doc)]
 use crate::{Length, Tag};
 
+#[cfg(feature = "alloc")]
+use alloc::boxed::Box;
+
 /// Decoding trait.
 ///
 /// This trait provides the core abstraction upon which all decoding operations
@@ -35,6 +39,17 @@ where
     }
 }
 
+/// Dummy implementation for [`PhantomData`] which allows deriving
+/// implementations on structs with phantom fields.
+impl<'a, T> Decode<'a> for PhantomData<T>
+where
+    T: ?Sized,
+{
+    fn decode<R: Reader<'a>>(_reader: &mut R) -> Result<PhantomData<T>> {
+        Ok(PhantomData)
+    }
+}
+
 /// Marker trait for data structures that can be decoded from DER without
 /// borrowing any data from the decoder.
 ///
@@ -52,14 +67,12 @@ impl<T> DecodeOwned for T where T: for<'a> Decode<'a> {}
 /// This trait is automatically impl'd for any type which impls both
 /// [`DecodeOwned`] and [`PemLabel`].
 #[cfg(feature = "pem")]
-#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
 pub trait DecodePem: DecodeOwned + PemLabel {
     /// Try to decode this type from PEM.
     fn from_pem(pem: impl AsRef<[u8]>) -> Result<Self>;
 }
 
 #[cfg(feature = "pem")]
-#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
 impl<T: DecodeOwned + PemLabel> DecodePem for T {
     fn from_pem(pem: impl AsRef<[u8]>) -> Result<Self> {
         let mut reader = PemReader::new(pem.as_ref())?;
@@ -74,3 +87,13 @@ pub trait DecodeValue<'a>: Sized {
     /// Attempt to decode this message using the provided [`Reader`].
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self>;
 }
+
+#[cfg(feature = "alloc")]
+impl<'a, T> DecodeValue<'a> for Box<T>
+where
+    T: DecodeValue<'a>,
+{
+    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+        Ok(Box::new(T::decode_value(reader, header)?))
+    }
+}
diff --git a/src/document.rs b/src/document.rs
index aa953cd..78355a6 100644
--- a/src/document.rs
+++ b/src/document.rs
@@ -27,7 +27,6 @@ use zeroize::{Zeroize, ZeroizeOnDrop, Zeroizing};
 ///
 /// The [`SecretDocument`] provides a wrapper for this type with additional
 /// hardening applied.
-#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 #[derive(Clone, Eq, PartialEq)]
 pub struct Document {
     /// ASN.1 DER encoded bytes.
@@ -45,7 +44,6 @@ impl Document {
 
     /// Convert to a [`SecretDocument`].
     #[cfg(feature = "zeroize")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "zeroize")))]
     pub fn into_secret(self) -> SecretDocument {
         SecretDocument(self)
     }
@@ -74,14 +72,13 @@ impl Document {
     /// Encode the provided type as ASN.1 DER, storing the resulting encoded DER
     /// as a [`Document`].
     pub fn encode_msg<T: Encode>(msg: &T) -> Result<Self> {
-        msg.to_vec()?.try_into()
+        msg.to_der()?.try_into()
     }
 
     /// Decode ASN.1 DER document from PEM.
     ///
     /// Returns the PEM label and decoded [`Document`] on success.
     #[cfg(feature = "pem")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
     pub fn from_pem(pem: &str) -> Result<(&str, Self)> {
         let (label, der_bytes) = pem::decode_vec(pem.as_bytes())?;
         Ok((label, der_bytes.try_into()?))
@@ -90,35 +87,30 @@ impl Document {
     /// Encode ASN.1 DER document as a PEM string with encapsulation boundaries
     /// containing the provided PEM type `label` (e.g. `CERTIFICATE`).
     #[cfg(feature = "pem")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
     pub fn to_pem(&self, label: &'static str, line_ending: pem::LineEnding) -> Result<String> {
         Ok(pem::encode_string(label, line_ending, self.as_bytes())?)
     }
 
     /// Read ASN.1 DER document from a file.
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn read_der_file(path: impl AsRef<Path>) -> Result<Self> {
         fs::read(path)?.try_into()
     }
 
     /// Write ASN.1 DER document to a file.
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn write_der_file(&self, path: impl AsRef<Path>) -> Result<()> {
         Ok(fs::write(path, self.as_bytes())?)
     }
 
     /// Read PEM-encoded ASN.1 DER document from a file.
     #[cfg(all(feature = "pem", feature = "std"))]
-    #[cfg_attr(docsrs, doc(cfg(all(feature = "pem", feature = "std"))))]
     pub fn read_pem_file(path: impl AsRef<Path>) -> Result<(String, Self)> {
         Self::from_pem(&fs::read_to_string(path)?).map(|(label, doc)| (label.to_owned(), doc))
     }
 
     /// Write PEM-encoded ASN.1 DER document to a file.
     #[cfg(all(feature = "pem", feature = "std"))]
-    #[cfg_attr(docsrs, doc(cfg(all(feature = "pem", feature = "std"))))]
     pub fn write_pem_file(
         &self,
         path: impl AsRef<Path>,
@@ -166,7 +158,7 @@ impl Encode for Document {
         Ok(self.len())
     }
 
-    fn encode(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode(&self, writer: &mut impl Writer) -> Result<()> {
         writer.write(self.as_bytes())
     }
 }
@@ -205,7 +197,6 @@ impl TryFrom<Vec<u8>> for Document {
 /// are zeroized-on-drop, and also using more restrictive file permissions when
 /// writing files to disk.
 #[cfg(feature = "zeroize")]
-#[cfg_attr(docsrs, doc(cfg(all(feature = "alloc", feature = "zeroize"))))]
 #[derive(Clone)]
 pub struct SecretDocument(Document);
 
@@ -238,14 +229,12 @@ impl SecretDocument {
 
     /// Decode ASN.1 DER document from PEM.
     #[cfg(feature = "pem")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
     pub fn from_pem(pem: &str) -> Result<(&str, Self)> {
         Document::from_pem(pem).map(|(label, doc)| (label, Self(doc)))
     }
 
     /// Encode ASN.1 DER document as a PEM string.
     #[cfg(feature = "pem")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
     pub fn to_pem(
         &self,
         label: &'static str,
@@ -256,28 +245,24 @@ impl SecretDocument {
 
     /// Read ASN.1 DER document from a file.
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn read_der_file(path: impl AsRef<Path>) -> Result<Self> {
         Document::read_der_file(path).map(Self)
     }
 
     /// Write ASN.1 DER document to a file.
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     pub fn write_der_file(&self, path: impl AsRef<Path>) -> Result<()> {
         write_secret_file(path, self.as_bytes())
     }
 
     /// Read PEM-encoded ASN.1 DER document from a file.
     #[cfg(all(feature = "pem", feature = "std"))]
-    #[cfg_attr(docsrs, doc(cfg(all(feature = "pem", feature = "std"))))]
     pub fn read_pem_file(path: impl AsRef<Path>) -> Result<(String, Self)> {
         Document::read_pem_file(path).map(|(label, doc)| (label, Self(doc)))
     }
 
     /// Write PEM-encoded ASN.1 DER document to a file.
     #[cfg(all(feature = "pem", feature = "std"))]
-    #[cfg_attr(docsrs, doc(cfg(all(feature = "pem", feature = "std"))))]
     pub fn write_pem_file(
         &self,
         path: impl AsRef<Path>,
diff --git a/src/encode.rs b/src/encode.rs
index 51fc13d..28d7cba 100644
--- a/src/encode.rs
+++ b/src/encode.rs
@@ -1,9 +1,10 @@
 //! Trait definition for [`Encode`].
 
 use crate::{Header, Length, Result, SliceWriter, Tagged, Writer};
+use core::marker::PhantomData;
 
 #[cfg(feature = "alloc")]
-use {alloc::vec::Vec, core::iter};
+use {alloc::boxed::Box, alloc::vec::Vec, core::iter};
 
 #[cfg(feature = "pem")]
 use {
@@ -24,7 +25,7 @@ pub trait Encode {
     fn encoded_len(&self) -> Result<Length>;
 
     /// Encode this value as ASN.1 DER using the provided [`Writer`].
-    fn encode(&self, encoder: &mut dyn Writer) -> Result<()>;
+    fn encode(&self, encoder: &mut impl Writer) -> Result<()>;
 
     /// Encode this value to the provided byte slice, returning a sub-slice
     /// containing the encoded message.
@@ -37,7 +38,6 @@ pub trait Encode {
     /// Encode this message as ASN.1 DER, appending it to the provided
     /// byte vector.
     #[cfg(feature = "alloc")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
     fn encode_to_vec(&self, buf: &mut Vec<u8>) -> Result<Length> {
         let expected_len = usize::try_from(self.encoded_len()?)?;
         buf.reserve(expected_len);
@@ -58,10 +58,9 @@ pub trait Encode {
         actual_len.try_into()
     }
 
-    /// Serialize this message as a byte vector.
+    /// Encode this type as DER, returning a byte vector.
     #[cfg(feature = "alloc")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
-    fn to_vec(&self) -> Result<Vec<u8>> {
+    fn to_der(&self) -> Result<Vec<u8>> {
         let mut buf = Vec::new();
         self.encode_to_vec(&mut buf)?;
         Ok(buf)
@@ -78,25 +77,38 @@ where
     }
 
     /// Encode this value as ASN.1 DER using the provided [`Writer`].
-    fn encode(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode(&self, writer: &mut impl Writer) -> Result<()> {
         self.header()?.encode(writer)?;
         self.encode_value(writer)
     }
 }
 
+/// Dummy implementation for [`PhantomData`] which allows deriving
+/// implementations on structs with phantom fields.
+impl<T> Encode for PhantomData<T>
+where
+    T: ?Sized,
+{
+    fn encoded_len(&self) -> Result<Length> {
+        Ok(Length::ZERO)
+    }
+
+    fn encode(&self, _writer: &mut impl Writer) -> Result<()> {
+        Ok(())
+    }
+}
+
 /// PEM encoding trait.
 ///
 /// This trait is automatically impl'd for any type which impls both
 /// [`Encode`] and [`PemLabel`].
 #[cfg(feature = "pem")]
-#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
 pub trait EncodePem: Encode + PemLabel {
     /// Try to encode this type as PEM.
     fn to_pem(&self, line_ending: LineEnding) -> Result<String>;
 }
 
 #[cfg(feature = "pem")]
-#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
 impl<T: Encode + PemLabel> EncodePem for T {
     fn to_pem(&self, line_ending: LineEnding) -> Result<String> {
         let der_len = usize::try_from(self.encoded_len()?)?;
@@ -129,5 +141,18 @@ pub trait EncodeValue {
 
     /// Encode value (sans [`Tag`]+[`Length`] header) as ASN.1 DER using the
     /// provided [`Writer`].
-    fn encode_value(&self, encoder: &mut dyn Writer) -> Result<()>;
+    fn encode_value(&self, encoder: &mut impl Writer) -> Result<()>;
+}
+
+#[cfg(feature = "alloc")]
+impl<T> EncodeValue for Box<T>
+where
+    T: EncodeValue,
+{
+    fn value_len(&self) -> Result<Length> {
+        T::value_len(self)
+    }
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+        T::encode_value(self, writer)
+    }
 }
diff --git a/src/encode_ref.rs b/src/encode_ref.rs
index c1e4f03..8a60a93 100644
--- a/src/encode_ref.rs
+++ b/src/encode_ref.rs
@@ -22,7 +22,7 @@ where
         self.0.encoded_len()
     }
 
-    fn encode(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode(&self, writer: &mut impl Writer) -> Result<()> {
         self.0.encode(writer)
     }
 }
@@ -47,7 +47,7 @@ where
         self.0.value_len()
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         self.0.encode_value(writer)
     }
 }
diff --git a/src/error.rs b/src/error.rs
index 5e492a4..902863d 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -174,7 +174,6 @@ pub enum ErrorKind {
 
     /// File not found error.
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     FileNotFound,
 
     /// Message is incomplete and does not contain all of the expected data.
@@ -194,9 +193,11 @@ pub enum ErrorKind {
 
     /// I/O errors.
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     Io(std::io::ErrorKind),
 
+    /// Indefinite length disallowed.
+    IndefiniteLength,
+
     /// Incorrect length for a given field.
     Length {
         /// Tag of the value being decoded.
@@ -221,12 +222,14 @@ pub enum ErrorKind {
     /// to determine which OID(s) are causing the error (and then potentially
     /// contribute upstream support for algorithms they care about).
     #[cfg(feature = "oid")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "oid")))]
     OidUnknown {
         /// OID value that was unrecognized by a parser for a DER-based format.
         oid: ObjectIdentifier,
     },
 
+    /// `SET` cannot contain duplicates.
+    SetDuplicate,
+
     /// `SET` ordering error: items not in canonical order.
     SetOrdering,
 
@@ -238,12 +241,10 @@ pub enum ErrorKind {
 
     /// PEM encoding errors.
     #[cfg(feature = "pem")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
     Pem(pem::Error),
 
     /// Permission denied reading file.
     #[cfg(feature = "std")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
     PermissionDenied,
 
     /// Reader does not support the requested operation.
@@ -321,6 +322,7 @@ impl fmt::Display for ErrorKind {
             ),
             #[cfg(feature = "std")]
             ErrorKind::Io(err) => write!(f, "I/O error: {:?}", err),
+            ErrorKind::IndefiniteLength => write!(f, "indefinite length disallowed"),
             ErrorKind::Length { tag } => write!(f, "incorrect length for {}", tag),
             ErrorKind::Noncanonical { tag } => {
                 write!(f, "ASN.1 {} not canonically encoded as DER", tag)
@@ -330,6 +332,7 @@ impl fmt::Display for ErrorKind {
             ErrorKind::OidUnknown { oid } => {
                 write!(f, "unknown/unsupported OID: {}", oid)
             }
+            ErrorKind::SetDuplicate => write!(f, "SET OF contains duplicate"),
             ErrorKind::SetOrdering => write!(f, "SET OF ordering error"),
             ErrorKind::Overflow => write!(f, "integer overflow"),
             ErrorKind::Overlength => write!(f, "ASN.1 DER message is too long"),
diff --git a/src/header.rs b/src/header.rs
index ddb484e..ad30381 100644
--- a/src/header.rs
+++ b/src/header.rs
@@ -44,7 +44,7 @@ impl Encode for Header {
         self.tag.encoded_len()? + self.length.encoded_len()?
     }
 
-    fn encode(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode(&self, writer: &mut impl Writer) -> Result<()> {
         self.tag.encode(writer)?;
         self.length.encode(writer)
     }
diff --git a/src/length.rs b/src/length.rs
index 76ee0e9..d183a69 100644
--- a/src/length.rs
+++ b/src/length.rs
@@ -14,6 +14,13 @@ const MAX_DER_OCTETS: usize = 5;
 /// Maximum length as a `u32` (256 MiB).
 const MAX_U32: u32 = 0xfff_ffff;
 
+/// Octet identifying an indefinite length as described in X.690 Section
+/// 8.1.3.6.1:
+///
+/// > The single octet shall have bit 8 set to one, and bits 7 to
+/// > 1 set to zero.
+const INDEFINITE_LENGTH_OCTET: u8 = 0b10000000; // 0x80
+
 /// ASN.1-encoded length.
 ///
 /// Maximum length is defined by the [`Length::MAX`] constant (256 MiB).
@@ -204,7 +211,8 @@ impl<'a> Decode<'a> for Length {
         match reader.read_byte()? {
             // Note: per X.690 Section 8.1.3.6.1 the byte 0x80 encodes indefinite
             // lengths, which are not allowed in DER, so disallow that byte.
-            len if len < 0x80 => Ok(len.into()),
+            len if len < INDEFINITE_LENGTH_OCTET => Ok(len.into()),
+            INDEFINITE_LENGTH_OCTET => Err(ErrorKind::IndefiniteLength.into()),
             // 1-4 byte variable-sized length prefix
             tag @ 0x81..=0x84 => {
                 let nbytes = tag.checked_sub(0x80).ok_or(ErrorKind::Overlength)? as usize;
@@ -246,7 +254,7 @@ impl Encode for Length {
         }
     }
 
-    fn encode(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode(&self, writer: &mut impl Writer) -> Result<()> {
         match self.initial_octet() {
             Some(tag_byte) => {
                 writer.write_byte(tag_byte)?;
@@ -286,9 +294,126 @@ impl fmt::Display for Length {
     }
 }
 
+// Implement by hand because the derive would create invalid values.
+// Generate a u32 with a valid range.
+#[cfg(feature = "arbitrary")]
+impl<'a> arbitrary::Arbitrary<'a> for Length {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        Ok(Self(u.int_in_range(0..=MAX_U32)?))
+    }
+
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        u32::size_hint(depth)
+    }
+}
+
+/// Length type with support for indefinite lengths as used by ASN.1 BER,
+/// as described in X.690 Section 8.1.3.6:
+///
+/// > 8.1.3.6 For the indefinite form, the length octets indicate that the
+/// > contents octets are terminated by end-of-contents
+/// > octets (see 8.1.5), and shall consist of a single octet.
+/// >
+/// > 8.1.3.6.1 The single octet shall have bit 8 set to one, and bits 7 to
+/// > 1 set to zero.
+/// >
+/// > 8.1.3.6.2 If this form of length is used, then end-of-contents octets
+/// > (see 8.1.5) shall be present in the encoding following the contents
+/// > octets.
+///
+/// Indefinite lengths are non-canonical and therefore invalid DER, however
+/// there are interoperability corner cases where we have little choice but to
+/// tolerate some BER productions where this is helpful.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+pub struct IndefiniteLength(Option<Length>);
+
+impl IndefiniteLength {
+    /// Length of `0`.
+    pub const ZERO: Self = Self(Some(Length::ZERO));
+
+    /// Length of `1`.
+    pub const ONE: Self = Self(Some(Length::ONE));
+
+    /// Indefinite length.
+    pub const INDEFINITE: Self = Self(None);
+}
+
+impl IndefiniteLength {
+    /// Create a definite length from a type which can be converted into a
+    /// `Length`.
+    pub fn new(length: impl Into<Length>) -> Self {
+        Self(Some(length.into()))
+    }
+
+    /// Is this length definite?
+    pub fn is_definite(self) -> bool {
+        self.0.is_some()
+    }
+    /// Is this length indefinite?
+    pub fn is_indefinite(self) -> bool {
+        self.0.is_none()
+    }
+}
+
+impl<'a> Decode<'a> for IndefiniteLength {
+    fn decode<R: Reader<'a>>(reader: &mut R) -> Result<IndefiniteLength> {
+        if reader.peek_byte() == Some(INDEFINITE_LENGTH_OCTET) {
+            // Consume the byte we already peeked at.
+            let byte = reader.read_byte()?;
+            debug_assert_eq!(byte, INDEFINITE_LENGTH_OCTET);
+
+            Ok(Self::INDEFINITE)
+        } else {
+            Length::decode(reader).map(Into::into)
+        }
+    }
+}
+
+impl Encode for IndefiniteLength {
+    fn encoded_len(&self) -> Result<Length> {
+        match self.0 {
+            Some(length) => length.encoded_len(),
+            None => Ok(Length::ONE),
+        }
+    }
+
+    fn encode(&self, writer: &mut impl Writer) -> Result<()> {
+        match self.0 {
+            Some(length) => length.encode(writer),
+            None => writer.write_byte(INDEFINITE_LENGTH_OCTET),
+        }
+    }
+}
+
+impl From<Length> for IndefiniteLength {
+    fn from(length: Length) -> IndefiniteLength {
+        Self(Some(length))
+    }
+}
+
+impl From<Option<Length>> for IndefiniteLength {
+    fn from(length: Option<Length>) -> IndefiniteLength {
+        IndefiniteLength(length)
+    }
+}
+
+impl From<IndefiniteLength> for Option<Length> {
+    fn from(length: IndefiniteLength) -> Option<Length> {
+        length.0
+    }
+}
+
+impl TryFrom<IndefiniteLength> for Length {
+    type Error = Error;
+
+    fn try_from(length: IndefiniteLength) -> Result<Length> {
+        length.0.ok_or_else(|| ErrorKind::IndefiniteLength.into())
+    }
+}
+
 #[cfg(test)]
 mod tests {
-    use super::Length;
+    use super::{IndefiniteLength, Length};
     use crate::{Decode, DerOrd, Encode, ErrorKind};
     use core::cmp::Ordering;
 
@@ -355,8 +480,22 @@ mod tests {
     }
 
     #[test]
-    fn reject_indefinite_lengths() {
+    fn indefinite_lengths() {
+        // DER disallows indefinite lengths
         assert!(Length::from_der(&[0x80]).is_err());
+
+        // The `IndefiniteLength` type supports them
+        let indefinite_length = IndefiniteLength::from_der(&[0x80]).unwrap();
+        assert!(indefinite_length.is_indefinite());
+        assert_eq!(indefinite_length, IndefiniteLength::INDEFINITE);
+
+        // It also supports definite lengths.
+        let length = IndefiniteLength::from_der(&[0x83, 0x01, 0x00, 0x00]).unwrap();
+        assert!(length.is_definite());
+        assert_eq!(
+            Length::try_from(0x10000u32).unwrap(),
+            length.try_into().unwrap()
+        );
     }
 
     #[test]
diff --git a/src/lib.rs b/src/lib.rs
index c8e7945..0bb32c9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,5 @@
 #![no_std]
-#![cfg_attr(docsrs, feature(doc_cfg))]
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
 #![doc = include_str!("../README.md")]
 #![doc(
     html_logo_url = "https://raw.githubusercontent.com/RustCrypto/media/6ee8e381/logo.svg",
@@ -15,6 +15,7 @@
     clippy::checked_conversions,
     clippy::implicit_saturating_sub,
     clippy::integer_arithmetic,
+    clippy::mod_module_files,
     clippy::panic,
     clippy::panic_in_result_fn,
     clippy::unwrap_used,
@@ -56,7 +57,7 @@
 //! - [`VideotexStringRef`]: ASN.1 `VideotexString`.
 //! - [`SequenceOf`]: ASN.1 `SEQUENCE OF`.
 //! - [`SetOf`], [`SetOfVec`]: ASN.1 `SET OF`.
-//! - [`UIntRef`]: ASN.1 unsigned `INTEGER` with raw access to encoded bytes.
+//! - [`UintRef`]: ASN.1 unsigned `INTEGER` with raw access to encoded bytes.
 //! - [`UtcTime`]: ASN.1 `UTCTime`.
 //! - [`Utf8StringRef`]: ASN.1 `UTF8String`.
 //!
@@ -139,33 +140,20 @@
 //!     }
 //! }
 //!
-//! impl<'a> Sequence<'a> for AlgorithmIdentifier<'a> {
-//!     // The `Sequence::fields` method is used for encoding and functions as
-//!     // a visitor for all of the fields in a message.
-//!     //
-//!     // To implement it, you must define a slice containing `Encode`
-//!     // trait objects, then pass it to the provided `field_encoder`
-//!     // function, which is implemented by the `der` crate and handles
-//!     // message serialization.
-//!     //
-//!     // Trait objects are used because they allow for slices containing
-//!     // heterogeneous field types, and a callback is used to allow for the
-//!     // construction of temporary field encoder types. The latter means
-//!     // that the fields of your Rust struct don't necessarily need to
-//!     // impl the `Encode` trait, but if they don't you must construct
-//!     // a temporary wrapper value which does.
-//!     //
-//!     // Types which impl the `Sequence` trait receive blanket impls of both
-//!     // the `Encode` and `Tagged` traits (where the latter is impl'd as
-//!     // `Tagged::TAG = der::Tag::Sequence`.
-//!     fn fields<F, T>(&self, field_encoder: F) -> der::Result<T>
-//!     where
-//!         F: FnOnce(&[&dyn Encode]) -> der::Result<T>,
-//!     {
-//!         field_encoder(&[&self.algorithm, &self.parameters])
+//! impl<'a> ::der::EncodeValue for AlgorithmIdentifier<'a> {
+//!     fn value_len(&self) -> ::der::Result<::der::Length> {
+//!         self.algorithm.encoded_len()? + self.parameters.encoded_len()?
+//!     }
+//!
+//!     fn encode_value(&self, writer: &mut impl ::der::Writer) -> ::der::Result<()> {
+//!         self.algorithm.encode(writer)?;
+//!         self.parameters.encode(writer)?;
+//!         Ok(())
 //!     }
 //! }
 //!
+//! impl<'a> Sequence<'a> for AlgorithmIdentifier<'a> {}
+//!
 //! // Example parameters value: OID for the NIST P-256 elliptic curve.
 //! let parameters = "1.2.840.10045.3.1.7".parse::<ObjectIdentifier>().unwrap();
 //!
@@ -182,7 +170,7 @@
 //! // If you would prefer to avoid allocations, you can create a byte array
 //! // as backing storage instead, pass that to `der::Encoder::new`, and then
 //! // encode the `parameters` value using `encoder.encode(parameters)`.
-//! let der_encoded_parameters = parameters.to_vec().unwrap();
+//! let der_encoded_parameters = parameters.to_der().unwrap();
 //!
 //! let algorithm_identifier = AlgorithmIdentifier {
 //!     // OID for `id-ecPublicKey`, if you're curious
@@ -201,7 +189,7 @@
 //! // reference to it, then encode the message using
 //! // `encoder.encode(algorithm_identifier)`, then finally `encoder.finish()`
 //! // to obtain a byte slice containing the encoded message.
-//! let der_encoded_algorithm_identifier = algorithm_identifier.to_vec().unwrap();
+//! let der_encoded_algorithm_identifier = algorithm_identifier.to_der().unwrap();
 //!
 //! // Deserialize the `AlgorithmIdentifier` we just serialized from ASN.1 DER
 //! // using `der::Decode::from_bytes`.
@@ -255,7 +243,7 @@
 //! };
 //!
 //! // Encode
-//! let der_encoded_algorithm_identifier = algorithm_identifier.to_vec().unwrap();
+//! let der_encoded_algorithm_identifier = algorithm_identifier.to_der().unwrap();
 //!
 //! // Decode
 //! let decoded_algorithm_identifier = AlgorithmIdentifier::from_der(
@@ -328,7 +316,7 @@
 //! [`SequenceOf`]: asn1::SequenceOf
 //! [`SetOf`]: asn1::SetOf
 //! [`SetOfVec`]: asn1::SetOfVec
-//! [`UIntRef`]: asn1::UIntRef
+//! [`UintRef`]: asn1::UintRef
 //! [`UtcTime`]: asn1::UtcTime
 //! [`Utf8StringRef`]: asn1::Utf8StringRef
 
@@ -344,9 +332,10 @@ extern crate alloc;
 extern crate std;
 
 pub mod asn1;
+pub mod referenced;
 
 pub(crate) mod arrayvec;
-mod byte_slice;
+mod bytes_ref;
 mod datetime;
 mod decode;
 mod encode;
@@ -356,12 +345,16 @@ mod header;
 mod length;
 mod ord;
 mod reader;
-mod str_slice;
+mod str_ref;
 mod tag;
 mod writer;
 
 #[cfg(feature = "alloc")]
+mod bytes_owned;
+#[cfg(feature = "alloc")]
 mod document;
+#[cfg(feature = "alloc")]
+mod str_owned;
 
 pub use crate::{
     asn1::{AnyRef, Choice, Sequence},
@@ -371,37 +364,35 @@ pub use crate::{
     encode_ref::{EncodeRef, EncodeValueRef},
     error::{Error, ErrorKind, Result},
     header::Header,
-    length::Length,
+    length::{IndefiniteLength, Length},
     ord::{DerOrd, ValueOrd},
-    reader::{slice::SliceReader, Reader},
+    reader::{nested::NestedReader, slice::SliceReader, Reader},
     tag::{Class, FixedTag, Tag, TagMode, TagNumber, Tagged},
     writer::{slice::SliceWriter, Writer},
 };
 
 #[cfg(feature = "alloc")]
-pub use crate::document::Document;
+pub use crate::{asn1::Any, document::Document};
 
 #[cfg(feature = "bigint")]
-#[cfg_attr(docsrs, doc(cfg(feature = "bigint")))]
 pub use crypto_bigint as bigint;
 
 #[cfg(feature = "derive")]
-#[cfg_attr(docsrs, doc(cfg(feature = "derive")))]
 pub use der_derive::{Choice, Enumerated, Sequence, ValueOrd};
 
+#[cfg(feature = "flagset")]
+pub use flagset;
+
 #[cfg(feature = "oid")]
-#[cfg_attr(docsrs, doc(cfg(feature = "oid")))]
 pub use const_oid as oid;
 
 #[cfg(feature = "pem")]
-#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
 pub use {
     crate::{decode::DecodePem, encode::EncodePem, reader::pem::PemReader, writer::pem::PemWriter},
     pem_rfc7468 as pem,
 };
 
 #[cfg(feature = "time")]
-#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
 pub use time;
 
 #[cfg(feature = "zeroize")]
@@ -410,4 +401,6 @@ pub use zeroize;
 #[cfg(all(feature = "alloc", feature = "zeroize"))]
 pub use crate::document::SecretDocument;
 
-pub(crate) use crate::{arrayvec::ArrayVec, byte_slice::ByteSlice, str_slice::StrSlice};
+pub(crate) use crate::{arrayvec::ArrayVec, bytes_ref::BytesRef, str_ref::StrRef};
+#[cfg(feature = "alloc")]
+pub(crate) use crate::{bytes_owned::BytesOwned, str_owned::StrOwned};
diff --git a/src/ord.rs b/src/ord.rs
index fd967bf..42d4623 100644
--- a/src/ord.rs
+++ b/src/ord.rs
@@ -1,7 +1,7 @@
 //! Ordering trait.
 
 use crate::{EncodeValue, Result, Tagged};
-use core::cmp::Ordering;
+use core::{cmp::Ordering, marker::PhantomData};
 
 /// DER ordering trait.
 ///
@@ -69,3 +69,17 @@ where
 
     Ok(length_ord)
 }
+
+/// Provide a no-op implementation for PhantomData
+impl<T> ValueOrd for PhantomData<T> {
+    fn value_cmp(&self, _other: &Self) -> Result<Ordering> {
+        Ok(Ordering::Equal)
+    }
+}
+
+/// Provide a no-op implementation for PhantomData
+impl<T> DerOrd for PhantomData<T> {
+    fn der_cmp(&self, _other: &Self) -> Result<Ordering> {
+        Ok(Ordering::Equal)
+    }
+}
diff --git a/src/reader.rs b/src/reader.rs
index b917323..ea52f7b 100644
--- a/src/reader.rs
+++ b/src/reader.rs
@@ -1,6 +1,6 @@
 //! Reader trait.
 
-mod nested;
+pub(crate) mod nested;
 #[cfg(feature = "pem")]
 pub(crate) mod pem;
 pub(crate) mod slice;
@@ -135,7 +135,6 @@ pub trait Reader<'r>: Sized {
 
     /// Read a byte vector of the given length.
     #[cfg(feature = "alloc")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
     fn read_vec(&mut self, len: Length) -> Result<Vec<u8>> {
         let mut bytes = vec![0u8; usize::try_from(len)?];
         self.read_into(&mut bytes)?;
diff --git a/src/reader/pem.rs b/src/reader/pem.rs
index 01bb4f2..f11341a 100644
--- a/src/reader/pem.rs
+++ b/src/reader/pem.rs
@@ -1,16 +1,134 @@
 //! Streaming PEM reader.
 
 use super::Reader;
-use crate::{ErrorKind, Header, Length, Result};
-use pem_rfc7468::Decoder;
+use crate::{Decode, Error, ErrorKind, Header, Length, Result};
+use core::cell::RefCell;
+
+#[allow(clippy::integer_arithmetic)]
+mod utils {
+    use crate::{Error, Length, Result};
+    use pem_rfc7468::Decoder;
+
+    #[derive(Clone)]
+    pub(super) struct BufReader<'i> {
+        /// Inner PEM decoder.
+        decoder: Decoder<'i>,
+
+        /// Remaining after base64 decoding
+        remaining: usize,
+
+        /// Read buffer
+        buf: [u8; BufReader::CAPACITY],
+
+        /// Position of the head in the buffer,
+        pos: usize,
+
+        /// Position of the tail in the buffer,
+        cap: usize,
+    }
+
+    impl<'i> BufReader<'i> {
+        const CAPACITY: usize = 256;
+
+        pub fn new(pem: &'i [u8]) -> Result<Self> {
+            let decoder = Decoder::new(pem)?;
+            let remaining = decoder.remaining_len();
+
+            Ok(Self {
+                decoder,
+                remaining,
+                buf: [0u8; 256],
+                pos: 0,
+                cap: 0,
+            })
+        }
+
+        pub fn remaining_len(&self) -> usize {
+            self.decoder.remaining_len() + self.cap - self.pos
+        }
+
+        fn fill_buffer(&mut self) -> Result<()> {
+            debug_assert!(self.pos <= self.cap);
+
+            if self.is_empty() {
+                self.pos = 0;
+                self.cap = 0;
+            }
+
+            let end = (self.cap + self.remaining).min(Self::CAPACITY);
+            let writable_slice = &mut self.buf[self.cap..end];
+            if writable_slice.is_empty() {
+                return Ok(());
+            }
+
+            let wrote = self.decoder.decode(writable_slice)?.len();
+            if wrote == 0 {
+                return Err(Error::incomplete(Length::try_from(self.pos)?));
+            }
+
+            self.cap += wrote;
+            self.remaining -= wrote;
+            debug_assert!(self.cap <= Self::CAPACITY);
+
+            Ok(())
+        }
+
+        /// Get the PEM label which will be used in the encapsulation boundaries
+        /// for this document.
+        pub fn type_label(&self) -> &'i str {
+            self.decoder.type_label()
+        }
+
+        fn is_empty(&self) -> bool {
+            self.pos == self.cap
+        }
+
+        fn as_slice(&self) -> &[u8] {
+            &self.buf[self.pos..self.cap]
+        }
+    }
+
+    impl<'i> BufReader<'i> {
+        pub fn peek_byte(&self) -> Option<u8> {
+            let s = self.as_slice();
+            s.first().copied()
+        }
+
+        pub fn copy_to_slice<'o>(&mut self, buf: &'o mut [u8]) -> Result<&'o [u8]> {
+            let mut output_pos = 0;
+
+            while output_pos < buf.len() {
+                if self.is_empty() {
+                    self.fill_buffer()?;
+                }
+
+                let available = &self.buf[self.pos..self.cap];
+                let window_len = (buf.len() - output_pos).min(available.len());
+                let window = &mut buf[output_pos..output_pos + window_len];
+
+                window.copy_from_slice(&available[..window_len]);
+                self.pos += window_len;
+                output_pos += window_len;
+            }
+
+            // Don't leave the read buffer empty for peek_byte()
+            if self.is_empty() && self.decoder.remaining_len() != 0 {
+                self.fill_buffer()?
+            }
+
+            debug_assert_eq!(output_pos, buf.len());
+
+            Ok(buf)
+        }
+    }
+}
 
 /// `Reader` type which decodes PEM on-the-fly.
 #[cfg(feature = "pem")]
-#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
 #[derive(Clone)]
 pub struct PemReader<'i> {
-    /// Inner PEM decoder.
-    decoder: Decoder<'i>,
+    /// Inner PEM decoder wrapped in a BufReader.
+    reader: RefCell<utils::BufReader<'i>>,
 
     /// Input length (in bytes after Base64 decoding).
     input_len: Length,
@@ -20,17 +138,16 @@ pub struct PemReader<'i> {
 }
 
 #[cfg(feature = "pem")]
-#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
 impl<'i> PemReader<'i> {
     /// Create a new PEM reader which decodes data on-the-fly.
     ///
     /// Uses the default 64-character line wrapping.
     pub fn new(pem: &'i [u8]) -> Result<Self> {
-        let decoder = Decoder::new(pem)?;
-        let input_len = Length::try_from(decoder.remaining_len())?;
+        let reader = utils::BufReader::new(pem)?;
+        let input_len = Length::try_from(reader.remaining_len())?;
 
         Ok(Self {
-            decoder,
+            reader: RefCell::new(reader),
             input_len,
             position: Length::ZERO,
         })
@@ -39,25 +156,30 @@ impl<'i> PemReader<'i> {
     /// Get the PEM label which will be used in the encapsulation boundaries
     /// for this document.
     pub fn type_label(&self) -> &'i str {
-        self.decoder.type_label()
+        self.reader.borrow().type_label()
     }
 }
 
 #[cfg(feature = "pem")]
-#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
 impl<'i> Reader<'i> for PemReader<'i> {
     fn input_len(&self) -> Length {
         self.input_len
     }
 
     fn peek_byte(&self) -> Option<u8> {
-        // TODO(tarcieri): lookahead buffer
-        None
+        if self.is_finished() {
+            None
+        } else {
+            self.reader.borrow().peek_byte()
+        }
     }
 
     fn peek_header(&self) -> Result<Header> {
-        // TODO(tarcieri): lookahead buffer
-        Err(ErrorKind::Reader.into())
+        if self.is_finished() {
+            Err(Error::incomplete(self.offset()))
+        } else {
+            Header::decode(&mut self.clone())
+        }
     }
 
     fn position(&self) -> Length {
@@ -70,12 +192,13 @@ impl<'i> Reader<'i> for PemReader<'i> {
     }
 
     fn read_into<'o>(&mut self, buf: &'o mut [u8]) -> Result<&'o [u8]> {
-        let bytes = self.decoder.decode(buf)?;
+        let bytes = self.reader.borrow_mut().copy_to_slice(buf)?;
+
         self.position = (self.position + bytes.len())?;
 
         debug_assert_eq!(
             self.position,
-            (self.input_len - Length::try_from(self.decoder.remaining_len())?)?
+            (self.input_len - Length::try_from(self.reader.borrow().remaining_len())?)?
         );
 
         Ok(bytes)
diff --git a/src/reader/slice.rs b/src/reader/slice.rs
index 6bab091..e78468f 100644
--- a/src/reader/slice.rs
+++ b/src/reader/slice.rs
@@ -1,12 +1,12 @@
 //! Slice reader.
 
-use crate::{ByteSlice, Decode, Error, ErrorKind, Header, Length, Reader, Result, Tag};
+use crate::{BytesRef, Decode, Error, ErrorKind, Header, Length, Reader, Result, Tag};
 
 /// [`Reader`] which consumes an input byte slice.
 #[derive(Clone, Debug)]
 pub struct SliceReader<'a> {
     /// Byte slice being decoded.
-    bytes: ByteSlice<'a>,
+    bytes: BytesRef<'a>,
 
     /// Did the decoding operation fail?
     failed: bool,
@@ -19,7 +19,7 @@ impl<'a> SliceReader<'a> {
     /// Create a new slice reader for the given byte slice.
     pub fn new(bytes: &'a [u8]) -> Result<Self> {
         Ok(Self {
-            bytes: ByteSlice::new(bytes)?,
+            bytes: BytesRef::new(bytes)?,
             failed: false,
             position: Length::ZERO,
         })
@@ -64,7 +64,7 @@ impl<'a> Reader<'a> for SliceReader<'a> {
     fn peek_byte(&self) -> Option<u8> {
         self.remaining()
             .ok()
-            .and_then(|bytes| bytes.get(0).cloned())
+            .and_then(|bytes| bytes.first().cloned())
     }
 
     fn peek_header(&self) -> Result<Header> {
diff --git a/src/referenced.rs b/src/referenced.rs
new file mode 100644
index 0000000..b0c8f03
--- /dev/null
+++ b/src/referenced.rs
@@ -0,0 +1,69 @@
+//! A module for working with referenced data.
+
+/// A trait for borrowing data from an owned struct
+pub trait OwnedToRef {
+    /// The resulting type referencing back to Self
+    type Borrowed<'a>
+    where
+        Self: 'a;
+
+    /// Creates a new object referencing back to the self for storage
+    fn owned_to_ref(&self) -> Self::Borrowed<'_>;
+}
+
+/// A trait for cloning a referenced structure and getting owned objects
+///
+/// This is the pendant to [`OwnedToRef`]
+pub trait RefToOwned<'a> {
+    /// The resulting type after obtaining ownership.
+    type Owned: OwnedToRef<Borrowed<'a> = Self>
+    where
+        Self: 'a;
+
+    /// Creates a new object taking ownership of the data
+    fn ref_to_owned(&self) -> Self::Owned;
+}
+
+impl<T> OwnedToRef for Option<T>
+where
+    T: OwnedToRef,
+{
+    type Borrowed<'a> = Option<T::Borrowed<'a>> where T: 'a;
+
+    fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+        self.as_ref().map(|o| o.owned_to_ref())
+    }
+}
+
+impl<'a, T> RefToOwned<'a> for Option<T>
+where
+    T: RefToOwned<'a> + 'a,
+    T::Owned: OwnedToRef,
+{
+    type Owned = Option<T::Owned>;
+    fn ref_to_owned(&self) -> Self::Owned {
+        self.as_ref().map(|o| o.ref_to_owned())
+    }
+}
+
+#[cfg(feature = "alloc")]
+mod allocating {
+    use super::{OwnedToRef, RefToOwned};
+    use alloc::boxed::Box;
+
+    impl<'a> RefToOwned<'a> for &'a [u8] {
+        type Owned = Box<[u8]>;
+
+        fn ref_to_owned(&self) -> Self::Owned {
+            Box::from(*self)
+        }
+    }
+
+    impl OwnedToRef for Box<[u8]> {
+        type Borrowed<'a> = &'a [u8];
+
+        fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+            self.as_ref()
+        }
+    }
+}
diff --git a/src/str_owned.rs b/src/str_owned.rs
new file mode 100644
index 0000000..20bfea5
--- /dev/null
+++ b/src/str_owned.rs
@@ -0,0 +1,104 @@
+//! Common handling for types backed by `String` with enforcement of a
+//! library-level length limitation i.e. `Length::max()`.
+
+use crate::{
+    referenced::OwnedToRef, BytesRef, DecodeValue, EncodeValue, Header, Length, Reader, Result,
+    StrRef, Writer,
+};
+use alloc::string::String;
+use core::str;
+
+/// String newtype which respects the [`Length::max`] limit.
+#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+pub struct StrOwned {
+    /// Inner value
+    pub(crate) inner: String,
+
+    /// Precomputed `Length` (avoids possible panicking conversions)
+    pub(crate) length: Length,
+}
+
+impl StrOwned {
+    /// Create a new [`StrOwned`], ensuring that the byte representation of
+    /// the provided `str` value is shorter than `Length::max()`.
+    pub fn new(s: String) -> Result<Self> {
+        let length = Length::try_from(s.as_bytes().len())?;
+
+        Ok(Self { inner: s, length })
+    }
+
+    /// Parse a [`String`] from UTF-8 encoded bytes.
+    pub fn from_bytes(bytes: &[u8]) -> Result<Self> {
+        Ok(Self {
+            inner: String::from_utf8(bytes.to_vec())?,
+            length: Length::try_from(bytes.len())?,
+        })
+    }
+
+    /// Borrow the inner `str`
+    pub fn as_str(&self) -> &str {
+        &self.inner
+    }
+
+    /// Borrow the inner byte slice
+    pub fn as_bytes(&self) -> &[u8] {
+        self.inner.as_bytes()
+    }
+
+    /// Get the [`Length`] of this [`StrOwned`]
+    pub fn len(&self) -> Length {
+        self.length
+    }
+
+    /// Is this [`StrOwned`] empty?
+    pub fn is_empty(&self) -> bool {
+        self.len() == Length::ZERO
+    }
+}
+
+impl AsRef<str> for StrOwned {
+    fn as_ref(&self) -> &str {
+        self.as_str()
+    }
+}
+
+impl AsRef<[u8]> for StrOwned {
+    fn as_ref(&self) -> &[u8] {
+        self.as_bytes()
+    }
+}
+
+impl<'a> DecodeValue<'a> for StrOwned {
+    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
+        Self::from_bytes(BytesRef::decode_value(reader, header)?.as_slice())
+    }
+}
+
+impl EncodeValue for StrOwned {
+    fn value_len(&self) -> Result<Length> {
+        Ok(self.length)
+    }
+
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
+        writer.write(self.as_ref())
+    }
+}
+
+impl From<StrRef<'_>> for StrOwned {
+    fn from(s: StrRef<'_>) -> StrOwned {
+        Self {
+            inner: String::from(s.inner),
+            length: s.length,
+        }
+    }
+}
+
+impl OwnedToRef for StrOwned {
+    type Borrowed<'a> = StrRef<'a>;
+    fn owned_to_ref(&self) -> Self::Borrowed<'_> {
+        StrRef {
+            length: self.length,
+            inner: self.inner.as_ref(),
+        }
+    }
+}
diff --git a/src/str_slice.rs b/src/str_ref.rs
index 8c94528..899c750 100644
--- a/src/str_slice.rs
+++ b/src/str_ref.rs
@@ -1,12 +1,12 @@
 //! Common handling for types backed by `str` slices with enforcement of a
 //! library-level length limitation i.e. `Length::max()`.
 
-use crate::{ByteSlice, DecodeValue, EncodeValue, Header, Length, Reader, Result, Writer};
+use crate::{BytesRef, DecodeValue, EncodeValue, Header, Length, Reader, Result, Writer};
 use core::str;
 
 /// String slice newtype which respects the [`Length::max`] limit.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
-pub struct StrSlice<'a> {
+pub struct StrRef<'a> {
     /// Inner value
     pub(crate) inner: &'a str,
 
@@ -14,8 +14,8 @@ pub struct StrSlice<'a> {
     pub(crate) length: Length,
 }
 
-impl<'a> StrSlice<'a> {
-    /// Create a new [`StrSlice`], ensuring that the byte representation of
+impl<'a> StrRef<'a> {
+    /// Create a new [`StrRef`], ensuring that the byte representation of
     /// the provided `str` value is shorter than `Length::max()`.
     pub fn new(s: &'a str) -> Result<Self> {
         Ok(Self {
@@ -24,7 +24,7 @@ impl<'a> StrSlice<'a> {
         })
     }
 
-    /// Parse a [`StrSlice`] from UTF-8 encoded bytes.
+    /// Parse a [`StrRef`] from UTF-8 encoded bytes.
     pub fn from_bytes(bytes: &'a [u8]) -> Result<Self> {
         Self::new(str::from_utf8(bytes)?)
     }
@@ -39,41 +39,54 @@ impl<'a> StrSlice<'a> {
         self.inner.as_bytes()
     }
 
-    /// Get the [`Length`] of this [`StrSlice`]
+    /// Get the [`Length`] of this [`StrRef`]
     pub fn len(self) -> Length {
         self.length
     }
 
-    /// Is this [`StrSlice`] empty?
+    /// Is this [`StrRef`] empty?
     pub fn is_empty(self) -> bool {
         self.len() == Length::ZERO
     }
 }
 
-impl AsRef<str> for StrSlice<'_> {
+impl AsRef<str> for StrRef<'_> {
     fn as_ref(&self) -> &str {
         self.as_str()
     }
 }
 
-impl AsRef<[u8]> for StrSlice<'_> {
+impl AsRef<[u8]> for StrRef<'_> {
     fn as_ref(&self) -> &[u8] {
         self.as_bytes()
     }
 }
 
-impl<'a> DecodeValue<'a> for StrSlice<'a> {
+impl<'a> DecodeValue<'a> for StrRef<'a> {
     fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
-        Self::from_bytes(ByteSlice::decode_value(reader, header)?.as_slice())
+        Self::from_bytes(BytesRef::decode_value(reader, header)?.as_slice())
     }
 }
 
-impl<'a> EncodeValue for StrSlice<'a> {
+impl<'a> EncodeValue for StrRef<'a> {
     fn value_len(&self) -> Result<Length> {
         Ok(self.length)
     }
 
-    fn encode_value(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
         writer.write(self.as_ref())
     }
 }
+
+#[cfg(feature = "alloc")]
+mod allocating {
+    use super::StrRef;
+    use crate::{referenced::RefToOwned, StrOwned};
+
+    impl<'a> RefToOwned<'a> for StrRef<'a> {
+        type Owned = StrOwned;
+        fn ref_to_owned(&self) -> Self::Owned {
+            StrOwned::from(*self)
+        }
+    }
+}
diff --git a/src/tag.rs b/src/tag.rs
index 0e7bf20..7a1fed1 100644
--- a/src/tag.rs
+++ b/src/tag.rs
@@ -1,4 +1,5 @@
 //! ASN.1 tags.
+#![cfg_attr(feature = "arbitrary", allow(clippy::integer_arithmetic))]
 
 mod class;
 mod mode;
@@ -46,6 +47,7 @@ impl<T: FixedTag> Tagged for T {
 /// - Bits 8/7: [`Class`]
 /// - Bit 6: primitive (0) or constructed (1)
 /// - Bits 5-1: tag number
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
 #[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord)]
 #[non_exhaustive]
 pub enum Tag {
@@ -211,7 +213,7 @@ impl Tag {
             Tag::UtcTime => 0x17,
             Tag::GeneralizedTime => 0x18,
             Tag::VisibleString => 0x1A,
-            Tag::BmpString => 0x1D,
+            Tag::BmpString => 0x1E,
             Tag::Application {
                 constructed,
                 number,
@@ -280,7 +282,7 @@ impl TryFrom<u8> for Tag {
             0x17 => Ok(Tag::UtcTime),
             0x18 => Ok(Tag::GeneralizedTime),
             0x1A => Ok(Tag::VisibleString),
-            0x1d => Ok(Tag::BmpString),
+            0x1E => Ok(Tag::BmpString),
             0x30 => Ok(Tag::Sequence), // constructed
             0x31 => Ok(Tag::Set),      // constructed
             0x40..=0x7E => Ok(Tag::Application {
@@ -323,7 +325,7 @@ impl Encode for Tag {
         Ok(Length::ONE)
     }
 
-    fn encode(&self, writer: &mut dyn Writer) -> Result<()> {
+    fn encode(&self, writer: &mut impl Writer) -> Result<()> {
         writer.write_byte(self.into())
     }
 }
diff --git a/src/tag/mode.rs b/src/tag/mode.rs
index 892ce3d..ecdaf02 100644
--- a/src/tag/mode.rs
+++ b/src/tag/mode.rs
@@ -4,11 +4,12 @@ use crate::{Error, ErrorKind, Result};
 use core::{fmt, str::FromStr};
 
 /// Tagging modes: `EXPLICIT` versus `IMPLICIT`.
-#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
+#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, PartialOrd, Ord)]
 pub enum TagMode {
     /// `EXPLICIT` tagging.
     ///
     /// Tag is added in addition to the inner tag of the type.
+    #[default]
     Explicit,
 
     /// `IMPLICIT` tagging.
@@ -17,12 +18,6 @@ pub enum TagMode {
     Implicit,
 }
 
-impl Default for TagMode {
-    fn default() -> TagMode {
-        TagMode::Explicit
-    }
-}
-
 impl FromStr for TagMode {
     type Err = Error;
 
diff --git a/src/tag/number.rs b/src/tag/number.rs
index 1930e94..6a7eaae 100644
--- a/src/tag/number.rs
+++ b/src/tag/number.rs
@@ -186,3 +186,16 @@ impl fmt::Display for TagNumber {
         write!(f, "{}", self.0)
     }
 }
+
+// Implement by hand because the derive would create invalid values.
+// Use the constructor to create a valid value.
+#[cfg(feature = "arbitrary")]
+impl<'a> arbitrary::Arbitrary<'a> for TagNumber {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        Ok(Self::new(u.int_in_range(0..=Self::MAX)?))
+    }
+
+    fn size_hint(depth: usize) -> (usize, Option<usize>) {
+        u8::size_hint(depth)
+    }
+}
diff --git a/src/writer.rs b/src/writer.rs
index 5e97744..164b215 100644
--- a/src/writer.rs
+++ b/src/writer.rs
@@ -21,7 +21,6 @@ pub trait Writer {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<W: io::Write> Writer for W {
     fn write(&mut self, slice: &[u8]) -> Result<()> {
         <Self as io::Write>::write(self, slice)?;
diff --git a/src/writer/pem.rs b/src/writer/pem.rs
index c554632..87a6f8f 100644
--- a/src/writer/pem.rs
+++ b/src/writer/pem.rs
@@ -5,7 +5,6 @@ use crate::Result;
 use pem_rfc7468::{Encoder, LineEnding};
 
 /// `Writer` type which outputs PEM-encoded data.
-#[cfg_attr(docsrs, doc(cfg(feature = "pem")))]
 pub struct PemWriter<'w>(Encoder<'static, 'w>);
 
 impl<'w> PemWriter<'w> {
diff --git a/tests/derive.rs b/tests/derive.rs
index dac14f8..a8c77fe 100644
--- a/tests/derive.rs
+++ b/tests/derive.rs
@@ -48,9 +48,8 @@ mod choice {
             }
         }
 
-        const UTC_TIMESTAMP_DER: &'static [u8] =
-            &hex!("17 0d 39 31 30 35 30 36 32 33 34 35 34 30 5a");
-        const GENERAL_TIMESTAMP_DER: &'static [u8] =
+        const UTC_TIMESTAMP_DER: &[u8] = &hex!("17 0d 39 31 30 35 30 36 32 33 34 35 34 30 5a");
+        const GENERAL_TIMESTAMP_DER: &[u8] =
             &hex!("18 0f 31 39 39 31 30 35 30 36 32 33 34 35 34 30 5a");
 
         #[test]
@@ -116,8 +115,8 @@ mod choice {
             }
         }
 
-        const BITSTRING_DER: &'static [u8] = &hex!("80 04 00 01 02 03");
-        const TIME_DER: &'static [u8] = &hex!("81 0f 31 39 39 31 30 35 30 36 32 33 34 35 34 30 5a");
+        const BITSTRING_DER: &[u8] = &hex!("80 04 00 01 02 03");
+        const TIME_DER: &[u8] = &hex!("81 0f 31 39 39 31 30 35 30 36 32 33 34 35 34 30 5a");
 
         #[test]
         fn decode() {
@@ -201,6 +200,7 @@ mod enumerated {
 /// Custom derive test cases for the `Sequence` macro.
 #[cfg(feature = "oid")]
 mod sequence {
+    use core::marker::PhantomData;
     use der::{
         asn1::{AnyRef, ObjectIdentifier, SetOf},
         Decode, Encode, Sequence, ValueOrd,
@@ -267,6 +267,9 @@ mod sequence {
             tag_mode = "IMPLICIT"
         )]
         pub only_contains_attribute_certs: bool,
+
+        /// Test handling of PhantomData.
+        pub phantom: PhantomData<()>,
     }
 
     // Extension as defined in [RFC 5280 Section 4.1.2.9].
@@ -432,8 +435,7 @@ mod sequence {
 
     #[test]
     fn decode() {
-        let algorithm_identifier =
-            AlgorithmIdentifier::from_der(&ALGORITHM_IDENTIFIER_DER).unwrap();
+        let algorithm_identifier = AlgorithmIdentifier::from_der(ALGORITHM_IDENTIFIER_DER).unwrap();
 
         assert_eq!(ID_EC_PUBLIC_KEY_OID, algorithm_identifier.algorithm);
         assert_eq!(
@@ -453,7 +455,7 @@ mod sequence {
 
         assert_eq!(
             ALGORITHM_IDENTIFIER_DER,
-            algorithm_identifier.to_vec().unwrap()
+            algorithm_identifier.to_der().unwrap()
         );
     }
 }
diff --git a/tests/set_of.rs b/tests/set_of.rs
index ba43d80..d583991 100644
--- a/tests/set_of.rs
+++ b/tests/set_of.rs
@@ -4,15 +4,21 @@
 
 use der::{asn1::SetOfVec, DerOrd};
 use proptest::{prelude::*, string::*};
+use std::collections::BTreeSet;
 
 proptest! {
     #[test]
     fn sort_equiv(bytes in bytes_regex(".{0,64}").unwrap()) {
-        let mut expected = bytes.clone();
-        expected.sort_by(|a, b| a.der_cmp(b).unwrap());
+        let mut uniq = BTreeSet::new();
 
-        let set = SetOfVec::try_from(bytes).unwrap();
-        prop_assert_eq!(expected.as_slice(), set.as_slice());
+        // Ensure there are no duplicates
+        if bytes.iter().copied().all(move |x| uniq.insert(x)) {
+            let mut expected = bytes.clone();
+            expected.sort_by(|a, b| a.der_cmp(b).unwrap());
+
+            let set = SetOfVec::try_from(bytes).unwrap();
+            prop_assert_eq!(expected.as_slice(), set.as_slice());
+        }
     }
 }