/*
* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
* 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.Confounder;
import sun.security.krb5.KrbCryptoException;
import sun.security.krb5.internal.*;
abstract class DesCbcEType extends EType {
protected abstract byte[] calculateChecksum(byte[] data, int size)
throws KrbCryptoException;
public int blockSize() {
return 8;
}
public int keyType() {
return Krb5.KEYTYPE_DES;
}
public int keySize() {
return 8;
}
/**
* Encrypts the data using DES in CBC mode.
* @param data the buffer for plain text.
* @param key the key to encrypt the data.
* @return the buffer for encrypted data.
*
* @written by Yanni Zhang, Dec 6 99.
*/
public byte[] encrypt(byte[] data, byte[] key, int usage)
throws KrbCryptoException {
byte[] ivec = new byte[keySize()];
return encrypt(data, key, ivec, usage);
}
/**
* Encrypts the data using DES in CBC mode.
* @param data the buffer for plain text.
* @param key the key to encrypt the data.
* @param ivec initialization vector.
* @return buffer for encrypted data.
*
* @modified by Yanni Zhang, Feb 24 00.
*/
public byte[] encrypt(byte[] data, byte[] key, byte[] ivec,
int usage) throws KrbCryptoException {
/*
* To meet export control requirements, double check that the
* key being used is no longer than 64 bits.
*
* Note that from a protocol point of view, an
* algorithm that is not DES will be rejected before this
* point. Also, a DES key that is not 64 bits will be
* rejected by a good implementations of JCE.
*/
if (key.length > 8)
throw new KrbCryptoException("Invalid DES Key!");
int new_size = data.length + confounderSize() + checksumSize();
byte[] new_data;
byte pad;
/*Data padding: using Kerberos 5 GSS-API mechanism (1.2.2.3), Jun 1996.
*Before encryption, plain text data is padded to the next highest multiple of blocksize.
*by appending between 1 and 8 bytes, the value of each such byte being the total number
*of pad bytes. For example, if new_size = 10, blockSize is 8, we should pad 2 bytes,
*and the value of each byte is 2.
*If plaintext data is a multiple of blocksize, we pad a 8 bytes of 8.
*/
if (new_size % blockSize() == 0) {
new_data = new byte[new_size + blockSize()];
pad = (byte)8;
}
else {
new_data = new byte[new_size + blockSize() - new_size % blockSize()];
pad = (byte)(blockSize() - new_size % blockSize());
}
for (int i = new_size; i < new_data.length; i++) {
new_data[i] = pad;
}
byte[] conf = Confounder.bytes(confounderSize());
System.arraycopy(conf, 0, new_data, 0, confounderSize());
System.arraycopy(data, 0, new_data, startOfData(), data.length);
byte[] cksum = calculateChecksum(new_data, new_data.length);
System.arraycopy(cksum, 0, new_data, startOfChecksum(),
checksumSize());
byte[] cipher = new byte[new_data.length];
Des.cbc_encrypt(new_data, cipher, key, ivec, true);
return cipher;
}
/**
* Decrypts the data using DES in CBC mode.
* @param cipher the input buffer.
* @param key the key to decrypt the data.
*
* @written by Yanni Zhang, Dec 6 99.
*/
public byte[] decrypt(byte[] cipher, byte[] key, int usage)
throws KrbApErrException, KrbCryptoException{
byte[] ivec = new byte[keySize()];
return decrypt(cipher, key, ivec, usage);
}
/**
* Decrypts the data using DES in CBC mode.
* @param cipher the input buffer.
* @param key the key to decrypt the data.
* @param ivec initialization vector.
*
* @modified by Yanni Zhang, Dec 6 99.
*/
public byte[] decrypt(byte[] cipher, byte[] key, byte[] ivec, int usage)
throws KrbApErrException, KrbCryptoException {
/*
* To meet export control requirements, double check that the
* key being used is no longer than 64 bits.
*
* Note that from a protocol point of view, an
* algorithm that is not DES will be rejected before this
* point. Also, a DES key that is not 64 bits will be
* rejected by a good JCE provider.
*/
if (key.length > 8)
throw new KrbCryptoException("Invalid DES Key!");
byte[] data = new byte[cipher.length];
Des.cbc_encrypt(cipher, data, key, ivec, false);
if (!isChecksumValid(data))
throw new KrbApErrException(Krb5.KRB_AP_ERR_BAD_INTEGRITY);
return data;
}
private void copyChecksumField(byte[] data, byte[] cksum) {
for (int i = 0; i < checksumSize(); i++)
data[startOfChecksum() + i] = cksum[i];
}
private byte[] checksumField(byte[] data) {
byte[] result = new byte[checksumSize()];
for (int i = 0; i < checksumSize(); i++)
result[i] = data[startOfChecksum() + i];
return result;
}
private void resetChecksumField(byte[] data) {
for (int i = startOfChecksum(); i < startOfChecksum() +
checksumSize(); i++)
data[i] = 0;
}
/*
// Not used.
public void setChecksum(byte[] data, int size) throws KrbCryptoException{
resetChecksumField(data);
byte[] cksum = calculateChecksum(data, size);
copyChecksumField(data, cksum);
}
*/
private byte[] generateChecksum(byte[] data) throws KrbCryptoException{
byte[] cksum1 = checksumField(data);
resetChecksumField(data);
byte[] cksum2 = calculateChecksum(data, data.length);
copyChecksumField(data, cksum1);
return cksum2;
}
private boolean isChecksumEqual(byte[] cksum1, byte[] cksum2) {
if (cksum1 == cksum2)
return true;
if ((cksum1 == null && cksum2 != null) ||
(cksum1 != null && cksum2 == null))
return false;
if (cksum1.length != cksum2.length)
return false;
for (int i = 0; i < cksum1.length; i++)
if (cksum1[i] != cksum2[i])
return false;
return true;
}
protected boolean isChecksumValid(byte[] data) throws KrbCryptoException {
byte[] cksum1 = checksumField(data);
byte[] cksum2 = generateChecksum(data);
return isChecksumEqual(cksum1, cksum2);
}
}