jdk/src/share/classes/com/sun/crypto/provider/CounterMode.java - edge/openjdk - Git at Google

 /*
  * Copyright (c) 2002, 201313, 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 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>
      * @return the length of the encrypted data
      */
     int encrypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
         return 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>
      * @return the length of the decrypted data
      */
     int decrypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
         return 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 int crypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
         int result = len;
         while (len-- > 0) {
             if (used >= blockSize) {
                 embeddedCipher.encryptBlock(counter, 0, encryptedCounter, 0);
                 increment(counter);
                 used = 0;
             }
             out[outOff++] = (byte)(in[inOff++] ^ encryptedCounter[used++]);
         }
         return result;
     }
 }
	/*
	* Copyright (c) 2002, 201313, 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 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>
	* @return the length of the encrypted data
	*/
	int encrypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
	return 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>
	* @return the length of the decrypted data
	*/
	int decrypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
	return 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 int crypt(byte[] in, int inOff, int len, byte[] out, int outOff) {
	int result = len;
	while (len-- > 0) {
	if (used >= blockSize) {
	embeddedCipher.encryptBlock(counter, 0, encryptedCounter, 0);
	increment(counter);
	used = 0;
	}
	out[outOff++] = (byte)(in[inOff++] ^ encryptedCounter[used++]);
	}
	return result;
	}
	}