--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/com/sun/crypto/provider/CounterMode.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,210 @@
+/*
+ * Copyright 2002-2007 Sun Microsystems, Inc. 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. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package com.sun.crypto.provider;
+
+import java.security.InvalidKeyException;
+
+/**
+ * This class represents ciphers in counter (CTR) 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 Andreas Sterbenz
+ * @since 1.4.2
+ */
+final class CounterMode extends FeedbackCipher {
+
+ // current counter value
+ private final byte[] counter;
+
+ // encrypted bytes of the previous counter value
+ private final byte[] encryptedCounter;
+
+ // number of bytes in encryptedCounter already used up
+ private int used;
+
+ // variables for save/restore calls
+ private byte[] counterSave = null;
+ private byte[] encryptedCounterSave = null;
+ private int usedSave = 0;
+
+ CounterMode(SymmetricCipher embeddedCipher) {
+ super(embeddedCipher);
+ counter = new byte[blockSize];
+ encryptedCounter = new byte[blockSize];
+ }
+
+ /**
+ * Gets the name of the feedback mechanism
+ *
+ * @return the name of the feedback mechanism
+ */
+ String getFeedback() {
+ return "CTR";
+ }
+
+ /**
+ * 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, counter, 0, blockSize);
+ used = blockSize;
+ }
+
+ /**
+ * Save the current content of this cipher.
+ */
+ void save() {
+ if (counterSave == null) {
+ counterSave = new byte[blockSize];
+ encryptedCounterSave = new byte[blockSize];
+ }
+ System.arraycopy(counter, 0, counterSave, 0, blockSize);
+ System.arraycopy(encryptedCounter, 0, encryptedCounterSave, 0,
+ blockSize);
+ usedSave = used;
+ }
+
+ /**
+ * Restores the content of this cipher to the previous saved one.
+ */
+ void restore() {
+ System.arraycopy(counterSave, 0, counter, 0, blockSize);
+ System.arraycopy(encryptedCounterSave, 0, encryptedCounter, 0,
+ blockSize);
+ used = usedSave;
+ }
+
+ /**
+ * 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);
+ }
+
+ /**
+ * 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 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 in the buffer with the input data to be encrypted
+ * @param inOffset the offset in <code>plain</code>
+ * @param len the length of the input data
+ * @param out the buffer for the result
+ * @param outOff the offset in <code>cipher</code>
+ */
+ void encrypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
+ crypt(in, inOff, len, out, outOff);
+ }
+
+ /**
+ * 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 in the buffer with the input data to be decrypted
+ * @param inOff the offset in <code>cipherOffset</code>
+ * @param len the length of the input data
+ * @param out the buffer for the result
+ * @param outOff the offset in <code>plain</code>
+ */
+ void decrypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
+ crypt(in, inOff, len, out, outOff);
+ }
+
+ /**
+ * Increment the counter value.
+ */
+ private static void increment(byte[] b) {
+ int n = b.length - 1;
+ while ((n >= 0) && (++b[n] == 0)) {
+ n--;
+ }
+ }
+
+ /**
+ * Do the actual encryption/decryption operation.
+ * Essentially we XOR the input plaintext/ciphertext stream with a
+ * keystream generated by encrypting the counter values. Counter values
+ * are encrypted on demand.
+ */
+ private void crypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
+ while (len-- > 0) {
+ if (used >= blockSize) {
+ embeddedCipher.encryptBlock(counter, 0, encryptedCounter, 0);
+ increment(counter);
+ used = 0;
+ }
+ out[outOff++] = (byte)(in[inOff++] ^ encryptedCounter[used++]);
+ }
+ }
+}