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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* 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.
*
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package com.sun.crypto.provider;
import java.security.InvalidKeyException;
/**
* This class implements the Triple DES algorithm (DES encryption, followed by
* DES decryption, followed by DES encryption) on a byte array of size
* <code>DES_BLOCK_SIZE</code>. Each DES operation has its own key.
*
* @author Gigi Ankeny
* @author Jan Luehe
*
*
* @see DESConstants
* @see DESCipher
*/
final class DESedeCrypt extends DESCrypt implements DESConstants {
/*
* the expanded key used in encrypt/decrypt/encrypt phase
*/
private byte[] key1 = null;
private byte[] key2 = null;
private byte[] key3 = null;
private byte[] buf1, buf2;
/*
* constructor
*/
DESedeCrypt() {
buf1 = new byte[DES_BLOCK_SIZE];
buf2 = new byte[DES_BLOCK_SIZE];
}
void init(boolean decrypting, String algorithm, byte[] keys)
throws InvalidKeyException {
if (!algorithm.equalsIgnoreCase("DESede")
&& !algorithm.equalsIgnoreCase("TripleDES")) {
throw new InvalidKeyException
("Wrong algorithm: DESede or TripleDES required");
}
if (keys.length != DES_BLOCK_SIZE * 3) {
throw new InvalidKeyException("Wrong key size");
}
byte[] keybuf = new byte[DES_BLOCK_SIZE];
// retrieve the first key
key1 = new byte[128];
System.arraycopy(keys, 0, keybuf, 0, DES_BLOCK_SIZE);
expandKey(keybuf);
System.arraycopy(expandedKey, 0, key1, 0, 128);
// check if the third key is the same
if (keyEquals(keybuf, 0, keys, DES_BLOCK_SIZE*2, DES_BLOCK_SIZE)) {
key3 = key1;
} else {
key3 = new byte[128];
System.arraycopy(keys, DES_BLOCK_SIZE*2, keybuf, 0,
DES_BLOCK_SIZE);
expandKey(keybuf);
System.arraycopy(expandedKey, 0, key3, 0, 128);
}
// retrieve the second key
key2 = new byte[128];
System.arraycopy(keys, DES_BLOCK_SIZE, keybuf, 0, DES_BLOCK_SIZE);
expandKey(keybuf);
System.arraycopy(expandedKey, 0, key2, 0, 128);
}
/**
* Performs encryption operation.
*
* <p>The input plain text <code>plain</code>, starting at
* <code>plainOffset</code> and ending at
* <code>(plainOffset + blockSize - 1)</code>, is encrypted.
* The result is stored in <code>cipher</code>, starting at
* <code>cipherOffset</code>.
*
* @param plain the buffer with the input data to be encrypted
* @param plainOffset the offset in <code>plain</code>
* @param cipher the buffer for the result
* @param cipherOffset the offset in <code>cipher</code>
*/
void encryptBlock(byte[] plain, int plainOffset,
byte[] cipher, int cipherOffset)
{
expandedKey = key1;
decrypting = false;
cipherBlock(plain, plainOffset, buf1, 0);
expandedKey = key2;
decrypting = true;
cipherBlock(buf1, 0, buf2, 0);
expandedKey = key3;
decrypting = false;
cipherBlock(buf2, 0, cipher, cipherOffset);
}
/**
* Performs decryption operation.
*
* <p>The input cipher text <code>cipher</code>, starting at
* <code>cipherOffset</code> and ending at
* <code>(cipherOffset + blockSize - 1)</code>, is decrypted.
* The result is stored in <code>plain</code>, starting at
* <code>plainOffset</code>.
*
* @param cipher the buffer with the input data to be decrypted
* @param cipherOffset the offset in <code>cipherOffset</code>
* @param plain the buffer for the result
* @param plainOffset the offset in <code>plain</code>
*/
void decryptBlock(byte[] cipher, int cipherOffset,
byte[] plain, int plainOffset)
{
expandedKey = key3;
decrypting = true;
cipherBlock(cipher, cipherOffset, buf1, 0);
expandedKey = key2;
decrypting = false;
cipherBlock(buf1, 0, buf2, 0);
expandedKey = key1;
decrypting = true;
cipherBlock(buf2, 0, plain, plainOffset);
}
private boolean keyEquals(byte[] key1, int off1,
byte[] key2, int off2, int len) {
for (int i=0; i<len; i++) {
if (key1[i+off1] != key2[i+off2])
return false;
}
return true;
}
}