/* * Copyright (c) 2004, 2007, 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. */ package com.sun.crypto.provider; import javax.crypto.IllegalBlockSizeException;import javax.crypto.ShortBufferException; /** * This class represents ciphers in cipher text stealing (CTS) mode. * <br>CTS provides a way to allow block ciphers to operate on partial * blocks without padding, and all bits of the message go through * the encryption algorithm, rather than simply being XOR'd. * <br>More details can be found in RFC 2040 section 8 "Description * of RC5-CTS". * * <p>This mode is implemented independently of a particular cipher. * Ciphers to which this mode should apply (e.g., DES) must be * <i>plugged-in</i> using the constructor. * * <p>NOTE#1: CTS requires the input data to be at least one block * long. Thus, callers of this class has to buffer the input data * to make sure the input data passed to encryptFinal()/decryptFinal() * is not shorter than a block. * <p>NOTE#2: This class does not deal with buffering or padding * just like all other cipher mode implementations. * * @author Valerie Peng */ final class CipherTextStealing extends CipherBlockChaining { CipherTextStealing(SymmetricCipher embeddedCipher) { super(embeddedCipher); } /** * Gets the name of this feedback mode. * * @return the string <code>CBC</code> */ String getFeedback() { return "CTS"; } /** * Performs the last encryption operation. * * <p>The input plain text <code>plain</code>, starting at * <code>plainOffset</code> and ending at * <code>(plainOffset + len - 1)</code>, is encrypted. * The result is stored in <code>cipher</code>, starting at * <code>cipherOffset</code>. * * <p>It is the application's responsibility to make sure that * <code>plainLen</code> is a multiple of the embedded cipher's block size, * as any excess bytes are ignored. * * @param plain the buffer with the input data to be encrypted * @param plainOffset the offset in <code>plain</code> * @param plainLen the length of the input data * @param cipher the buffer for the result * @param cipherOffset the offset in <code>cipher</code> */ void encryptFinal(byte[] plain, int plainOffset, int plainLen, byte[] cipher, int cipherOffset) throws IllegalBlockSizeException { if (plainLen < blockSize) { throw new IllegalBlockSizeException("input is too short!"); } else if (plainLen == blockSize) { encrypt(plain, plainOffset, plainLen, cipher, cipherOffset); } else { // number of bytes in the last block int nLeft = plainLen % blockSize; if (nLeft == 0) { encrypt(plain, plainOffset, plainLen, cipher, cipherOffset); // swap the last two blocks after encryption int lastBlkIndex = cipherOffset + plainLen - blockSize; int nextToLastBlkIndex = lastBlkIndex - blockSize; byte[] tmp = new byte[blockSize]; System.arraycopy(cipher, lastBlkIndex, tmp, 0, blockSize); System.arraycopy(cipher, nextToLastBlkIndex, cipher, lastBlkIndex, blockSize); System.arraycopy(tmp, 0, cipher, nextToLastBlkIndex, blockSize); } else { int newPlainLen = plainLen - (blockSize + nLeft); if (newPlainLen > 0) { encrypt(plain, plainOffset, newPlainLen, cipher, cipherOffset); plainOffset += newPlainLen; cipherOffset += newPlainLen; } // Do final CTS step for last two blocks (the second of which // may or may not be incomplete). byte[] tmp = new byte[blockSize]; // now encrypt the next-to-last block for (int i = 0; i < blockSize; i++) { tmp[i] = (byte) (plain[plainOffset+i] ^ r[i]); } byte[] tmp2 = new byte[blockSize]; embeddedCipher.encryptBlock(tmp, 0, tmp2, 0); System.arraycopy(tmp2, 0, cipher, cipherOffset+blockSize, nLeft); // encrypt the last block for (int i=0; i<nLeft; i++) { tmp2[i] = (byte) (plain[plainOffset+blockSize+i] ^ tmp2[i]); } embeddedCipher.encryptBlock(tmp2, 0, cipher, cipherOffset); } } } /** * Performs decryption operation. * * <p>The input cipher text <code>cipher</code>, starting at * <code>cipherOffset</code> and ending at * <code>(cipherOffset + len - 1)</code>, is decrypted. * The result is stored in <code>plain</code>, starting at * <code>plainOffset</code>. * * <p>It is the application's responsibility to make sure that * <code>cipherLen</code> is a multiple of the embedded cipher's block * size, as any excess bytes are ignored. * * <p>It is also the application's responsibility to make sure that * <code>init</code> has been called before this method is called. * (This check is omitted here, to avoid double checking.) * * @param cipher the buffer with the input data to be decrypted * @param cipherOffset the offset in <code>cipherOffset</code> * @param cipherLen the length of the input data * @param plain the buffer for the result * @param plainOffset the offset in <code>plain</code> */ void decryptFinal(byte[] cipher, int cipherOffset, int cipherLen, byte[] plain, int plainOffset) throws IllegalBlockSizeException { if (cipherLen < blockSize) { throw new IllegalBlockSizeException("input is too short!"); } else if (cipherLen == blockSize) { decrypt(cipher, cipherOffset, cipherLen, plain, plainOffset); } else { // number of bytes in the last block int nLeft = cipherLen % blockSize; if (nLeft == 0) { // swap the last two blocks before decryption int lastBlkIndex = cipherOffset + cipherLen - blockSize; int nextToLastBlkIndex = cipherOffset + cipherLen - 2*blockSize; byte[] tmp = new byte[2*blockSize]; System.arraycopy(cipher, lastBlkIndex, tmp, 0, blockSize); System.arraycopy(cipher, nextToLastBlkIndex, tmp, blockSize, blockSize); int cipherLen2 = cipherLen-2*blockSize; decrypt(cipher, cipherOffset, cipherLen2, plain, plainOffset); decrypt(tmp, 0, 2*blockSize, plain, plainOffset+cipherLen2); } else { int newCipherLen = cipherLen-(blockSize+nLeft); if (newCipherLen > 0) { decrypt(cipher, cipherOffset, newCipherLen, plain, plainOffset); cipherOffset += newCipherLen; plainOffset += newCipherLen; } // Do final CTS step for last two blocks (the second of which // may or may not be incomplete). // now decrypt the next-to-last block byte[] tmp = new byte[blockSize]; embeddedCipher.decryptBlock(cipher, cipherOffset, tmp, 0); for (int i = 0; i < nLeft; i++) { plain[plainOffset+blockSize+i] = (byte) (cipher[cipherOffset+blockSize+i] ^ tmp[i]); } // decrypt the last block System.arraycopy(cipher, cipherOffset+blockSize, tmp, 0, nLeft); embeddedCipher.decryptBlock(tmp, 0, plain, plainOffset); //System.arraycopy(r, 0, tmp, 0, r.length); for (int i=0; i<blockSize; i++) { plain[plainOffset+i] = (byte) (plain[plainOffset+i]^r[i]); } } } }}
/*
* Copyright (c) 2004, 2007, 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.
*/
package com.sun.crypto.provider;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.ShortBufferException;
/**
* This class represents ciphers in cipher text stealing (CTS) mode.
* <br>CTS provides a way to allow block ciphers to operate on partial
* blocks without padding, and all bits of the message go through
* the encryption algorithm, rather than simply being XOR'd.
* <br>More details can be found in RFC 2040 section 8 "Description
* of RC5-CTS".
*
* <p>This mode is implemented independently of a particular cipher.
* Ciphers to which this mode should apply (e.g., DES) must be
* <i>plugged-in</i> using the constructor.
*
* <p>NOTE#1: CTS requires the input data to be at least one block
* long. Thus, callers of this class has to buffer the input data
* to make sure the input data passed to encryptFinal()/decryptFinal()
* is not shorter than a block.
* <p>NOTE#2: This class does not deal with buffering or padding
* just like all other cipher mode implementations.
*
* @author Valerie Peng
*/
final class CipherTextStealing extends CipherBlockChaining {
CipherTextStealing(SymmetricCipher embeddedCipher) {
super(embeddedCipher);
}
/**
* Gets the name of this feedback mode.
*
* @return the string <code>CBC</code>
*/
String getFeedback() {
return "CTS";
}
/**
* Performs the last encryption operation.
*
* <p>The input plain text <code>plain</code>, starting at
* <code>plainOffset</code> and ending at
* <code>(plainOffset + len - 1)</code>, is encrypted.
* The result is stored in <code>cipher</code>, starting at
* <code>cipherOffset</code>.
*
* <p>It is the application's responsibility to make sure that
* <code>plainLen</code> is a multiple of the embedded cipher's block size,
* as any excess bytes are ignored.
*
* @param plain the buffer with the input data to be encrypted
* @param plainOffset the offset in <code>plain</code>
* @param plainLen the length of the input data
* @param cipher the buffer for the result
* @param cipherOffset the offset in <code>cipher</code>
*/
void encryptFinal(byte[] plain, int plainOffset, int plainLen,
byte[] cipher, int cipherOffset)
throws IllegalBlockSizeException {
if (plainLen < blockSize) {
throw new IllegalBlockSizeException("input is too short!");
} else if (plainLen == blockSize) {
encrypt(plain, plainOffset, plainLen, cipher, cipherOffset);
} else {
// number of bytes in the last block
int nLeft = plainLen % blockSize;
if (nLeft == 0) {
encrypt(plain, plainOffset, plainLen, cipher, cipherOffset);
// swap the last two blocks after encryption
int lastBlkIndex = cipherOffset + plainLen - blockSize;
int nextToLastBlkIndex = lastBlkIndex - blockSize;
byte[] tmp = new byte[blockSize];
System.arraycopy(cipher, lastBlkIndex, tmp, 0, blockSize);
System.arraycopy(cipher, nextToLastBlkIndex,
cipher, lastBlkIndex, blockSize);
System.arraycopy(tmp, 0, cipher, nextToLastBlkIndex,
blockSize);
} else {
int newPlainLen = plainLen - (blockSize + nLeft);
if (newPlainLen > 0) {
encrypt(plain, plainOffset, newPlainLen, cipher,
cipherOffset);
plainOffset += newPlainLen;
cipherOffset += newPlainLen;
}
// Do final CTS step for last two blocks (the second of which
// may or may not be incomplete).
byte[] tmp = new byte[blockSize];
// now encrypt the next-to-last block
for (int i = 0; i < blockSize; i++) {
tmp[i] = (byte) (plain[plainOffset+i] ^ r[i]);
}
byte[] tmp2 = new byte[blockSize];
embeddedCipher.encryptBlock(tmp, 0, tmp2, 0);
System.arraycopy(tmp2, 0, cipher,
cipherOffset+blockSize, nLeft);
// encrypt the last block
for (int i=0; i<nLeft; i++) {
tmp2[i] = (byte)
(plain[plainOffset+blockSize+i] ^ tmp2[i]);
}
embeddedCipher.encryptBlock(tmp2, 0, cipher, cipherOffset);
}
}
}
/**
* Performs decryption operation.
*
* <p>The input cipher text <code>cipher</code>, starting at
* <code>cipherOffset</code> and ending at
* <code>(cipherOffset + len - 1)</code>, is decrypted.
* The result is stored in <code>plain</code>, starting at
* <code>plainOffset</code>.
*
* <p>It is the application's responsibility to make sure that
* <code>cipherLen</code> is a multiple of the embedded cipher's block
* size, as any excess bytes are ignored.
*
* <p>It is also the application's responsibility to make sure that
* <code>init</code> has been called before this method is called.
* (This check is omitted here, to avoid double checking.)
*
* @param cipher the buffer with the input data to be decrypted
* @param cipherOffset the offset in <code>cipherOffset</code>
* @param cipherLen the length of the input data
* @param plain the buffer for the result
* @param plainOffset the offset in <code>plain</code>
*/
void decryptFinal(byte[] cipher, int cipherOffset, int cipherLen,
byte[] plain, int plainOffset)
throws IllegalBlockSizeException {
if (cipherLen < blockSize) {
throw new IllegalBlockSizeException("input is too short!");
} else if (cipherLen == blockSize) {
decrypt(cipher, cipherOffset, cipherLen, plain, plainOffset);
} else {
// number of bytes in the last block
int nLeft = cipherLen % blockSize;
if (nLeft == 0) {
// swap the last two blocks before decryption
int lastBlkIndex = cipherOffset + cipherLen - blockSize;
int nextToLastBlkIndex =
cipherOffset + cipherLen - 2*blockSize;
byte[] tmp = new byte[2*blockSize];
System.arraycopy(cipher, lastBlkIndex, tmp, 0, blockSize);
System.arraycopy(cipher, nextToLastBlkIndex,
tmp, blockSize, blockSize);
int cipherLen2 = cipherLen-2*blockSize;
decrypt(cipher, cipherOffset, cipherLen2, plain, plainOffset);
decrypt(tmp, 0, 2*blockSize, plain, plainOffset+cipherLen2);
} else {
int newCipherLen = cipherLen-(blockSize+nLeft);
if (newCipherLen > 0) {
decrypt(cipher, cipherOffset, newCipherLen, plain,
plainOffset);
cipherOffset += newCipherLen;
plainOffset += newCipherLen;
}
// Do final CTS step for last two blocks (the second of which
// may or may not be incomplete).
// now decrypt the next-to-last block
byte[] tmp = new byte[blockSize];
embeddedCipher.decryptBlock(cipher, cipherOffset, tmp, 0);
for (int i = 0; i < nLeft; i++) {
plain[plainOffset+blockSize+i] =
(byte) (cipher[cipherOffset+blockSize+i] ^ tmp[i]);
}
// decrypt the last block
System.arraycopy(cipher, cipherOffset+blockSize, tmp, 0,
nLeft);
embeddedCipher.decryptBlock(tmp, 0, plain, plainOffset);
//System.arraycopy(r, 0, tmp, 0, r.length);
for (int i=0; i<blockSize; i++) {
plain[plainOffset+i] = (byte)
(plain[plainOffset+i]^r[i]);
}
}
}
}
}