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/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* (C) Copyright IBM Corp. 1999 All Rights Reserved.
* Copyright 1997 The Open Group Research Institute. All rights reserved.
*/
package sun.security.krb5.internal.crypto;
import sun.security.krb5.Checksum;
import sun.security.krb5.Confounder;
import sun.security.krb5.KrbCryptoException;
import sun.security.krb5.internal.*;
import javax.crypto.spec.DESKeySpec;
import java.security.MessageDigest;
import java.security.InvalidKeyException;
public final class RsaMd5DesCksumType extends CksumType {
public RsaMd5DesCksumType() {
}
public int confounderSize() {
return 8;
}
public int cksumType() {
return Checksum.CKSUMTYPE_RSA_MD5_DES;
}
public boolean isKeyed() {
return true;
}
public int cksumSize() {
return 24;
}
public int keyType() {
return Krb5.KEYTYPE_DES;
}
public int keySize() {
return 8;
}
/**
* Calculates keyed checksum.
* @param data the data used to generate the checksum.
* @param size length of the data.
* @param key the key used to encrypt the checksum.
* @return keyed checksum.
*
* @modified by Yanni Zhang, 12/08/99.
*/
public byte[] calculateChecksum(byte[] data, int size, byte[] key,
int usage) throws KrbCryptoException {
//prepend confounder
byte[] new_data = new byte[size + confounderSize()];
byte[] conf = Confounder.bytes(confounderSize());
System.arraycopy(conf, 0, new_data, 0, confounderSize());
System.arraycopy(data, 0, new_data, confounderSize(), size);
//calculate md5 cksum
byte[] mdc_cksum = calculateRawChecksum(new_data, new_data.length);
byte[] cksum = new byte[cksumSize()];
System.arraycopy(conf, 0, cksum, 0, confounderSize());
System.arraycopy(mdc_cksum, 0, cksum, confounderSize(),
cksumSize() - confounderSize());
//compute modified key
byte[] new_key = new byte[keySize()];
System.arraycopy(key, 0, new_key, 0, key.length);
for (int i = 0; i < new_key.length; i++)
new_key[i] = (byte)(new_key[i] ^ 0xf0);
//check for weak keys
try {
if (DESKeySpec.isWeak(new_key, 0)) {
new_key[7] = (byte)(new_key[7] ^ 0xF0);
}
} catch (InvalidKeyException ex) {
// swallow, since it should never happen
}
byte[] ivec = new byte[new_key.length];
//des-cbc encrypt
byte[] enc_cksum = new byte[cksum.length];
Des.cbc_encrypt(cksum, enc_cksum, new_key, ivec, true);
return enc_cksum;
}
/**
* Verifies keyed checksum.
* @param data the data.
* @param size the length of data.
* @param key the key used to encrypt the checksum.
* @param checksum
* @return true if verification is successful.
*
* @modified by Yanni Zhang, 12/08/99.
*/
public boolean verifyChecksum(byte[] data, int size,
byte[] key, byte[] checksum, int usage) throws KrbCryptoException {
//decrypt checksum
byte[] cksum = decryptKeyedChecksum(checksum, key);
//prepend confounder
byte[] new_data = new byte[size + confounderSize()];
System.arraycopy(cksum, 0, new_data, 0, confounderSize());
System.arraycopy(data, 0, new_data, confounderSize(), size);
byte[] new_cksum = calculateRawChecksum(new_data, new_data.length);
//extract original cksum value
byte[] orig_cksum = new byte[cksumSize() - confounderSize()];
System.arraycopy(cksum, confounderSize(), orig_cksum, 0,
cksumSize() - confounderSize());
return isChecksumEqual(orig_cksum, new_cksum);
}
/**
* Decrypts keyed checksum.
* @param enc_cksum the buffer for encrypted checksum.
* @param key the key.
* @return the checksum.
*
* @modified by Yanni Zhang, 12/08/99.
*/
private byte[] decryptKeyedChecksum(byte[] enc_cksum, byte[] key) throws KrbCryptoException {
//compute modified key
byte[] new_key = new byte[keySize()];
System.arraycopy(key, 0, new_key, 0, key.length);
for (int i = 0; i < new_key.length; i++)
new_key[i] = (byte)(new_key[i] ^ 0xf0);
//check for weak keys
try {
if (DESKeySpec.isWeak(new_key, 0)) {
new_key[7] = (byte)(new_key[7] ^ 0xF0);
}
} catch (InvalidKeyException ex) {
// swallow, since it should never happen
}
byte[] ivec = new byte[new_key.length];
byte[] cksum = new byte[enc_cksum.length];
Des.cbc_encrypt(enc_cksum, cksum, new_key, ivec, false);
return cksum;
}
/**
* Calculates checksum using MD5.
* @param data the data used to generate the checksum.
* @param size length of the data.
* @return the checksum.
*
* @modified by Yanni Zhang, 12/08/99.
*/
private byte[] calculateRawChecksum(byte[] data, int size) throws KrbCryptoException{
MessageDigest md5;
byte[] result = null;
try {
md5 = MessageDigest.getInstance("MD5");
} catch (Exception e) {
throw new KrbCryptoException("JCE provider may not be installed. " + e.getMessage());
}
try {
md5.update(data);
result = md5.digest();
} catch (Exception e) {
throw new KrbCryptoException(e.getMessage());
}
return result;
}
}
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