/* * Copyright (c) 1997, 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 java.security.InvalidKeyException; /** * This class represents ciphers in output-feedback (OFB) mode. * * <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: This class does not deal with buffering or padding. * * @author Gigi Ankeny */final class OutputFeedback extends FeedbackCipher { /* * output buffer */ private byte[] k = null; /* * register buffer */ private byte[] register = null; /* * number of bytes for each stream unit, defaults to the blocksize * of the embedded cipher */ private int numBytes; // variables for save/restore calls private byte[] registerSave = null; OutputFeedback(SymmetricCipher embeddedCipher, int numBytes) { super(embeddedCipher); if (numBytes > blockSize) { numBytes = blockSize; } this.numBytes = numBytes; k = new byte[blockSize]; register = new byte[blockSize]; } /** * Gets the name of this feedback mode. * * @return the string <code>OFB</code> */ String getFeedback() { return "OFB"; } /** * Initializes the cipher in the specified mode with the given key * and iv. * * @param decrypting flag indicating encryption or decryption * @param algorithm the algorithm name * @param key the key * @param iv the iv * * @exception InvalidKeyException if the given key is inappropriate for * initializing this cipher */ void init(boolean decrypting, String algorithm, byte[] key, byte[] iv) throws InvalidKeyException { if ((key == null) || (iv == null) || (iv.length != blockSize)) { throw new InvalidKeyException("Internal error"); } this.iv = iv; reset(); // always encrypt mode for embedded cipher embeddedCipher.init(false, algorithm, key); } /** * Resets the iv to its original value. * This is used when doFinal is called in the Cipher class, so that the * cipher can be reused (with its original iv). */ void reset() { System.arraycopy(iv, 0, register, 0, blockSize); } /** * Save the current content of this cipher. */ void save() { if (registerSave == null) { registerSave = new byte[blockSize]; } System.arraycopy(register, 0, registerSave, 0, blockSize); } /** * Restores the content of this cipher to the previous saved one. */ void restore() { System.arraycopy(registerSave, 0, register, 0, blockSize); } /** * Performs 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 stream unit size * <code>numBytes</code>, 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 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 encrypt(byte[] plain, int plainOffset, int plainLen, byte[] cipher, int cipherOffset) { int i; int len = blockSize - numBytes; int loopCount = plainLen / numBytes; int oddBytes = plainLen % numBytes; if (len == 0) { for (; loopCount > 0; plainOffset += numBytes, cipherOffset += numBytes, loopCount--) { embeddedCipher.encryptBlock(register, 0, k, 0); for (i=0; i<numBytes; i++) cipher[i+cipherOffset] = (byte)(k[i] ^ plain[i+plainOffset]); System.arraycopy(k, 0, register, 0, numBytes); } if (oddBytes > 0) { embeddedCipher.encryptBlock(register, 0, k, 0); for (i=0; i<oddBytes; i++) cipher[i+cipherOffset] = (byte)(k[i] ^ plain[i+plainOffset]); System.arraycopy(k, 0, register, 0, numBytes); } } else { for (; loopCount > 0; plainOffset += numBytes, cipherOffset += numBytes, loopCount--) { embeddedCipher.encryptBlock(register, 0, k, 0); for (i=0; i<numBytes; i++) cipher[i+cipherOffset] = (byte)(k[i] ^ plain[i+plainOffset]); System.arraycopy(register, numBytes, register, 0, len); System.arraycopy(k, 0, register, len, numBytes); } if (oddBytes > 0) { embeddedCipher.encryptBlock(register, 0, k, 0); for (i=0; i<oddBytes; i++) cipher[i+cipherOffset] = (byte)(k[i] ^ plain[i+plainOffset]); System.arraycopy(register, numBytes, register, 0, len); System.arraycopy(k, 0, register, len, numBytes); } } } /** * 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 stream unit size * <code>numBytes</code>, 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 decrypt(byte[] cipher, int cipherOffset, int cipherLen, byte[] plain, int plainOffset) { // OFB encrypt and decrypt are identical encrypt(cipher, cipherOffset, cipherLen, plain, plainOffset); }}
/*
* Copyright (c) 1997, 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 java.security.InvalidKeyException;
/**
* This class represents ciphers in output-feedback (OFB) mode.
*
* <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: This class does not deal with buffering or padding.
*
* @author Gigi Ankeny
*/
final class OutputFeedback extends FeedbackCipher {
/*
* output buffer
*/
private byte[] k = null;
/*
* register buffer
*/
private byte[] register = null;
/*
* number of bytes for each stream unit, defaults to the blocksize
* of the embedded cipher
*/
private int numBytes;
// variables for save/restore calls
private byte[] registerSave = null;
OutputFeedback(SymmetricCipher embeddedCipher, int numBytes) {
super(embeddedCipher);
if (numBytes > blockSize) {
numBytes = blockSize;
}
this.numBytes = numBytes;
k = new byte[blockSize];
register = new byte[blockSize];
}
/**
* Gets the name of this feedback mode.
*
* @return the string <code>OFB</code>
*/
String getFeedback() {
return "OFB";
}
/**
* Initializes the cipher in the specified mode with the given key
* and iv.
*
* @param decrypting flag indicating encryption or decryption
* @param algorithm the algorithm name
* @param key the key
* @param iv the iv
*
* @exception InvalidKeyException if the given key is inappropriate for
* initializing this cipher
*/
void init(boolean decrypting, String algorithm, byte[] key, byte[] iv)
throws InvalidKeyException {
if ((key == null) || (iv == null) || (iv.length != blockSize)) {
throw new InvalidKeyException("Internal error");
}
this.iv = iv;
reset();
// always encrypt mode for embedded cipher
embeddedCipher.init(false, algorithm, key);
}
/**
* Resets the iv to its original value.
* This is used when doFinal is called in the Cipher class, so that the
* cipher can be reused (with its original iv).
*/
void reset() {
System.arraycopy(iv, 0, register, 0, blockSize);
}
/**
* Save the current content of this cipher.
*/
void save() {
if (registerSave == null) {
registerSave = new byte[blockSize];
}
System.arraycopy(register, 0, registerSave, 0, blockSize);
}
/**
* Restores the content of this cipher to the previous saved one.
*/
void restore() {
System.arraycopy(registerSave, 0, register, 0, blockSize);
}
/**
* Performs 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 stream unit size
* <code>numBytes</code>, 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 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 encrypt(byte[] plain, int plainOffset, int plainLen,
byte[] cipher, int cipherOffset)
{
int i;
int len = blockSize - numBytes;
int loopCount = plainLen / numBytes;
int oddBytes = plainLen % numBytes;
if (len == 0) {
for (; loopCount > 0;
plainOffset += numBytes, cipherOffset += numBytes,
loopCount--) {
embeddedCipher.encryptBlock(register, 0, k, 0);
for (i=0; i<numBytes; i++)
cipher[i+cipherOffset] =
(byte)(k[i] ^ plain[i+plainOffset]);
System.arraycopy(k, 0, register, 0, numBytes);
}
if (oddBytes > 0) {
embeddedCipher.encryptBlock(register, 0, k, 0);
for (i=0; i<oddBytes; i++)
cipher[i+cipherOffset] =
(byte)(k[i] ^ plain[i+plainOffset]);
System.arraycopy(k, 0, register, 0, numBytes);
}
} else {
for (; loopCount > 0;
plainOffset += numBytes, cipherOffset += numBytes,
loopCount--) {
embeddedCipher.encryptBlock(register, 0, k, 0);
for (i=0; i<numBytes; i++)
cipher[i+cipherOffset] =
(byte)(k[i] ^ plain[i+plainOffset]);
System.arraycopy(register, numBytes, register, 0, len);
System.arraycopy(k, 0, register, len, numBytes);
}
if (oddBytes > 0) {
embeddedCipher.encryptBlock(register, 0, k, 0);
for (i=0; i<oddBytes; i++)
cipher[i+cipherOffset] =
(byte)(k[i] ^ plain[i+plainOffset]);
System.arraycopy(register, numBytes, register, 0, len);
System.arraycopy(k, 0, register, len, numBytes);
}
}
}
/**
* 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 stream unit size
* <code>numBytes</code>, 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 decrypt(byte[] cipher, int cipherOffset, int cipherLen,
byte[] plain, int plainOffset)
{
// OFB encrypt and decrypt are identical
encrypt(cipher, cipherOffset, cipherLen, plain, plainOffset);
}
}