summaryrefslogtreecommitdiff
path: root/libc/rsa.c
diff options
context:
space:
mode:
Diffstat (limited to 'libc/rsa.c')
-rw-r--r--libc/rsa.c168
1 files changed, 0 insertions, 168 deletions
diff --git a/libc/rsa.c b/libc/rsa.c
deleted file mode 100644
index 9c5636b..0000000
--- a/libc/rsa.c
+++ /dev/null
@@ -1,168 +0,0 @@
-// Copyright 2008-2010 Google Inc. All Rights Reserved.
-// Author: mschilder@google.com (Marius Schilder)
-
-#include "rsa.h"
-#include "sha.h"
-
-// a[] -= mod
-static void subM(RSAPublicKey key,
- uint32_t* a) {
- int64_t A = 0;
- int i;
- for (i = 0; i < key->len; ++i) {
- A += (uint64_t)a[i] - key->n[i];
- a[i] = (uint32_t)A;
- A >>= 32;
- }
-}
-
-// return a[] >= mod
-static int geM(RSAPublicKey key,
- const uint32_t* a) {
- int i;
- for (i = key->len; i;) {
- --i;
- if (a[i] < key->n[i]) return 0;
- if (a[i] > key->n[i]) return 1;
- }
- return 1; // equal
-}
-
-// montgomery c[] += a * b[] / R % mod
-static void montMulAdd(RSAPublicKey key,
- uint32_t* c,
- const uint32_t a,
- const uint32_t* b) {
- uint64_t A = (uint64_t)a * b[0] + c[0];
- uint32_t d0 = (uint32_t)A * key->n0inv;
- uint64_t B = (uint64_t)d0 * key->n[0] + (uint32_t)A;
- int i;
-
- for (i = 1; i < key->len; ++i) {
- A = (A >> 32) + (uint64_t)a * b[i] + c[i];
- B = (B >> 32) + (uint64_t)d0 * key->n[i] + (uint32_t)A;
- c[i - 1] = (uint32_t)B;
- }
-
- A = (A >> 32) + (B >> 32);
-
- c[i - 1] = (uint32_t)A;
-
- if (A >> 32) {
- subM(key, c);
- }
-}
-
-// montgomery c[] = a[] * b[] / R % mod
-static void montMul(RSAPublicKey key,
- uint32_t* c,
- const uint32_t* a,
- const uint32_t* b) {
- int i;
- for (i = 0; i < key->len; ++i) {
- c[i] = 0;
- }
- for (i = 0; i < key->len; ++i) {
- montMulAdd(key, c, a[i], b);
- }
-}
-
-// In-place public exponentiation.
-// Input and output big-endian byte array in inout.
-static void modpowF4(RSAPublicKey key,
- uint8_t* inout) {
- uint32_t a[RSANUMWORDS];
- uint32_t aR[RSANUMWORDS];
- uint32_t aaR[RSANUMWORDS];
- uint32_t* aaa = aaR; // Re-use location.
- int i;
-
- // Convert from big endian byte array to little endian word array.
- for (i = 0; i < key->len; ++i) {
- uint32_t tmp =
- (inout[((key->len - 1 - i) * 4) + 0] << 24) |
- (inout[((key->len - 1 - i) * 4) + 1] << 16) |
- (inout[((key->len - 1 - i) * 4) + 2] << 8) |
- (inout[((key->len - 1 - i) * 4) + 3] << 0);
- a[i] = tmp;
- }
-
- montMul(key, aR, a, key->rr); // aR = a * RR / R mod M
- for (i = 0; i < 16; i += 2) {
- montMul(key, aaR, aR, aR); // aaR = aR * aR / R mod M
- montMul(key, aR, aaR, aaR); // aR = aaR * aaR / R mod M
- }
- montMul(key, aaa, aR, a); // aaa = aR * a / R mod M
-
- // Make sure aaa < mod; aaa is at most 1x mod too large.
- if (geM(key, aaa)) {
- subM(key, aaa);
- }
-
- // Convert to bigendian byte array
- for (i = key->len - 1; i >= 0; --i) {
- uint32_t tmp = aaa[i];
- *inout++ = tmp >> 24;
- *inout++ = tmp >> 16;
- *inout++ = tmp >> 8;
- *inout++ = tmp >> 0;
- }
-}
-
-// Expected PKCS1.5 signature padding bytes, for a keytool RSA signature.
-// Has the 0-length optional parameter encoded in the ASN1 (as opposed to the
-// other flavor which omits the optional parameter entirely). This code does not
-// accept signatures without the optional parameter.
-/*
-static const uint8_t padding[RSANUMBYTES] = {
-0x00,0x01,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x00,0x30,0x21,0x30,0x09,0x06,0x05,0x2b,0x0e,0x03,0x02,0x1a,0x05,0x00,0x04,0x14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
-};
-*/
-
-// SHA-1 of PKCS1.5 signature padding for 2048 bit, as above.
-// At the location of the bytes of the hash all 00 are hashed.
-static const uint8_t kExpectedPadShaRsa2048[SHA_DIGEST_SIZE] = {
- 0xdc, 0xbd, 0xbe, 0x42, 0xd5, 0xf5, 0xa7, 0x2e, 0x6e, 0xfc,
- 0xf5, 0x5d, 0xaf, 0x9d, 0xea, 0x68, 0x7c, 0xfb, 0xf1, 0x67
-};
-
-// Verify a 2048 bit RSA PKCS1.5 signature against an expected SHA-1 hash.
-// Returns 0 on failure, 1 on success.
-int RSA_verify(RSAPublicKey key,
- const uint8_t* signature,
- const int len,
- const uint8_t* sha) {
- uint8_t buf[RSANUMBYTES];
- int i;
-
- if (key->len != RSANUMWORDS) {
- return 0; // Wrong key passed in.
- }
-
- if (len != sizeof(buf)) {
- return 0; // Wrong input length.
- }
-
- for (i = 0; i < len; ++i) { // Copy input to local workspace.
- buf[i] = signature[i];
- }
-
- modpowF4(key, buf); // In-place exponentiation.
-
- // Xor sha portion, so it all becomes 00 iff equal.
- for (i = len - SHA_DIGEST_SIZE; i < len; ++i) {
- buf[i] ^= *sha++;
- }
-
- // Hash resulting buf, in-place.
- SHA(buf, len, buf);
-
- // Compare against expected hash value.
- for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
- if (buf[i] != kExpectedPadShaRsa2048[i]) {
- return 0;
- }
- }
-
- return 1; // All checked out OK.
-}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-06 14:19:35 +0000