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/*
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* Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package com.sun.crypto.provider;
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import java.security.InvalidKeyException;
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/**
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* This class implements the Triple DES algorithm (DES encryption, followed by
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* DES decryption, followed by DES encryption) on a byte array of size
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* <code>DES_BLOCK_SIZE</code>. Each DES operation has its own key.
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*
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* @author Gigi Ankeny
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* @author Jan Luehe
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*
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*
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* @see DESConstants
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* @see DESCipher
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*/
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final class DESedeCrypt extends DESCrypt implements DESConstants {
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/*
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* the expanded key used in encrypt/decrypt/encrypt phase
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*/
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private byte[] key1 = null;
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private byte[] key2 = null;
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private byte[] key3 = null;
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private byte[] buf1, buf2;
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/*
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* constructor
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*/
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DESedeCrypt() {
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buf1 = new byte[DES_BLOCK_SIZE];
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buf2 = new byte[DES_BLOCK_SIZE];
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}
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void init(boolean decrypting, String algorithm, byte[] keys)
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throws InvalidKeyException {
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if (!algorithm.equalsIgnoreCase("DESede")
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&& !algorithm.equalsIgnoreCase("TripleDES")) {
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throw new InvalidKeyException
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("Wrong algorithm: DESede or TripleDES required");
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}
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if (keys.length != DES_BLOCK_SIZE * 3) {
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throw new InvalidKeyException("Wrong key size");
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}
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byte[] keybuf = new byte[DES_BLOCK_SIZE];
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// retrieve the first key
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key1 = new byte[128];
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System.arraycopy(keys, 0, keybuf, 0, DES_BLOCK_SIZE);
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expandKey(keybuf);
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System.arraycopy(expandedKey, 0, key1, 0, 128);
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// check if the third key is the same
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if (keyEquals(keybuf, 0, keys, DES_BLOCK_SIZE*2, DES_BLOCK_SIZE)) {
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key3 = key1;
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} else {
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key3 = new byte[128];
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System.arraycopy(keys, DES_BLOCK_SIZE*2, keybuf, 0,
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DES_BLOCK_SIZE);
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expandKey(keybuf);
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System.arraycopy(expandedKey, 0, key3, 0, 128);
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}
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// retrieve the second key
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key2 = new byte[128];
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System.arraycopy(keys, DES_BLOCK_SIZE, keybuf, 0, DES_BLOCK_SIZE);
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expandKey(keybuf);
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System.arraycopy(expandedKey, 0, key2, 0, 128);
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}
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/**
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* Performs encryption operation.
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*
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* <p>The input plain text <code>plain</code>, starting at
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* <code>plainOffset</code> and ending at
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* <code>(plainOffset + blockSize - 1)</code>, is encrypted.
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* The result is stored in <code>cipher</code>, starting at
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* <code>cipherOffset</code>.
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*
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* @param plain the buffer with the input data to be encrypted
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* @param plainOffset the offset in <code>plain</code>
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* @param cipher the buffer for the result
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* @param cipherOffset the offset in <code>cipher</code>
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*/
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void encryptBlock(byte[] plain, int plainOffset,
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byte[] cipher, int cipherOffset)
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{
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expandedKey = key1;
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decrypting = false;
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cipherBlock(plain, plainOffset, buf1, 0);
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expandedKey = key2;
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decrypting = true;
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cipherBlock(buf1, 0, buf2, 0);
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expandedKey = key3;
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decrypting = false;
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cipherBlock(buf2, 0, cipher, cipherOffset);
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}
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/**
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* Performs decryption operation.
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*
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* <p>The input cipher text <code>cipher</code>, starting at
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* <code>cipherOffset</code> and ending at
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* <code>(cipherOffset + blockSize - 1)</code>, is decrypted.
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* The result is stored in <code>plain</code>, starting at
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* <code>plainOffset</code>.
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*
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* @param cipher the buffer with the input data to be decrypted
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* @param cipherOffset the offset in <code>cipherOffset</code>
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* @param plain the buffer for the result
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* @param plainOffset the offset in <code>plain</code>
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*/
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void decryptBlock(byte[] cipher, int cipherOffset,
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byte[] plain, int plainOffset)
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{
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expandedKey = key3;
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decrypting = true;
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cipherBlock(cipher, cipherOffset, buf1, 0);
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expandedKey = key2;
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decrypting = false;
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cipherBlock(buf1, 0, buf2, 0);
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expandedKey = key1;
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decrypting = true;
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cipherBlock(buf2, 0, plain, plainOffset);
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}
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private boolean keyEquals(byte[] key1, int off1,
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byte[] key2, int off2, int len) {
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for (int i=0; i<len; i++) {
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if (key1[i+off1] != key2[i+off2])
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return false;
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}
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return true;
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}
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}
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