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

 /*
  * Copyright (c) 1997, 2013, 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 cipher-feedback (CFB) 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 CipherFeedback extends FeedbackCipher {

     /*
      * encrypt/decrypt output buffer
      */
     private final byte[] k;

     /*
      * register value, initialized with iv
      */
     private final byte[] register;

     /*
      * 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;

     CipherFeedback(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>CFB</code>
      */
     String getFeedback() {
         return "CFB";
     }

     /**
      * 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>
      * @return the length of the encrypted data
      */
     int encrypt(byte[] plain, int plainOffset, int plainLen,
                 byte[] cipher, int cipherOffset)
     {
         int i, len;
         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 < blockSize; i++)
                     register[i] = cipher[i+cipherOffset] =
                         (byte)(k[i] ^ plain[i+plainOffset]);
             }
             if (oddBytes > 0) {
                 embeddedCipher.encryptBlock(register, 0, k, 0);
                 for (i=0; i<oddBytes; i++)
                     register[i] = cipher[i+cipherOffset] =
                         (byte)(k[i] ^ plain[i+plainOffset]);
             }
         } else {
             for (; loopCount > 0 ;
                  plainOffset += numBytes, cipherOffset += numBytes,
                  loopCount--) {
                 embeddedCipher.encryptBlock(register, 0, k, 0);
                 System.arraycopy(register, numBytes, register, 0, len);
                 for (i=0; i<numBytes; i++)
                     register[i+len] = cipher[i+cipherOffset] =
                         (byte)(k[i] ^ plain[i+plainOffset]);

             }
             if (oddBytes != 0) {
                 embeddedCipher.encryptBlock(register, 0, k, 0);
                 System.arraycopy(register, numBytes, register, 0, len);
                 for (i=0; i<oddBytes; i++) {
                     register[i+len] = cipher[i+cipherOffset] =
                         (byte)(k[i] ^ plain[i+plainOffset]);
                 }
             }
         }
         return plainLen;
     }

     /**
      * 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>
      * @return the length of the decrypted data
      */
     int decrypt(byte[] cipher, int cipherOffset, int cipherLen,
                 byte[] plain, int plainOffset)
     {
         int i, len;
         len = blockSize - numBytes;
         int loopCount = cipherLen / numBytes;
         int oddBytes = cipherLen % numBytes;

         if (len == 0) {
             for (; loopCount > 0;
                  plainOffset += numBytes, cipherOffset += numBytes,
                  loopCount--) {
                 embeddedCipher.encryptBlock(register, 0, k, 0);
                 for (i = 0; i < blockSize; i++) {
                     register[i] = cipher[i+cipherOffset];
                     plain[i+plainOffset]
                         = (byte)(cipher[i+cipherOffset] ^ k[i]);
                 }
             }
             if (oddBytes > 0) {
                 embeddedCipher.encryptBlock(register, 0, k, 0);
                 for (i=0; i<oddBytes; i++) {
                     register[i] = cipher[i+cipherOffset];
                     plain[i+plainOffset]
                         = (byte)(cipher[i+cipherOffset] ^ k[i]);
                 }
             }
         } else {
             for (; loopCount > 0;
                  plainOffset += numBytes, cipherOffset += numBytes,
                  loopCount--) {
                 embeddedCipher.encryptBlock(register, 0, k, 0);
                 System.arraycopy(register, numBytes, register, 0, len);
                 for (i=0; i<numBytes; i++) {
                     register[i+len] = cipher[i+cipherOffset];
                     plain[i+plainOffset]
                         = (byte)(cipher[i+cipherOffset] ^ k[i]);
                 }
             }
             if (oddBytes != 0) {
                 embeddedCipher.encryptBlock(register, 0, k, 0);
                 System.arraycopy(register, numBytes, register, 0, len);
                 for (i=0; i<oddBytes; i++) {
                     register[i+len] = cipher[i+cipherOffset];
                     plain[i+plainOffset]
                         = (byte)(cipher[i+cipherOffset] ^ k[i]);
                 }
             }
         }
         return cipherLen;
     }
 }
	/*
	* Copyright (c) 1997, 2013, 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 cipher-feedback (CFB) 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 CipherFeedback extends FeedbackCipher {

	/*
	* encrypt/decrypt output buffer
	*/
	private final byte[] k;

	/*
	* register value, initialized with iv
	*/
	private final byte[] register;

	/*
	* 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;

	CipherFeedback(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>CFB</code>
	*/
	String getFeedback() {
	return "CFB";
	}

	/**
	* 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>
	* @return the length of the encrypted data
	*/
	int encrypt(byte[] plain, int plainOffset, int plainLen,
	byte[] cipher, int cipherOffset)
	{
	int i, len;
	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 < blockSize; i++)
	register[i] = cipher[i+cipherOffset] =
	(byte)(k[i] ^ plain[i+plainOffset]);
	}
	if (oddBytes > 0) {
	embeddedCipher.encryptBlock(register, 0, k, 0);
	for (i=0; i<oddBytes; i++)
	register[i] = cipher[i+cipherOffset] =
	(byte)(k[i] ^ plain[i+plainOffset]);
	}
	} else {
	for (; loopCount > 0 ;
	plainOffset += numBytes, cipherOffset += numBytes,
	loopCount--) {
	embeddedCipher.encryptBlock(register, 0, k, 0);
	System.arraycopy(register, numBytes, register, 0, len);
	for (i=0; i<numBytes; i++)
	register[i+len] = cipher[i+cipherOffset] =
	(byte)(k[i] ^ plain[i+plainOffset]);

	}
	if (oddBytes != 0) {
	embeddedCipher.encryptBlock(register, 0, k, 0);
	System.arraycopy(register, numBytes, register, 0, len);
	for (i=0; i<oddBytes; i++) {
	register[i+len] = cipher[i+cipherOffset] =
	(byte)(k[i] ^ plain[i+plainOffset]);
	}
	}
	}
	return plainLen;
	}

	/**
	* 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>
	* @return the length of the decrypted data
	*/
	int decrypt(byte[] cipher, int cipherOffset, int cipherLen,
	byte[] plain, int plainOffset)
	{
	int i, len;
	len = blockSize - numBytes;
	int loopCount = cipherLen / numBytes;
	int oddBytes = cipherLen % numBytes;

	if (len == 0) {
	for (; loopCount > 0;
	plainOffset += numBytes, cipherOffset += numBytes,
	loopCount--) {
	embeddedCipher.encryptBlock(register, 0, k, 0);
	for (i = 0; i < blockSize; i++) {
	register[i] = cipher[i+cipherOffset];
	plain[i+plainOffset]
	= (byte)(cipher[i+cipherOffset] ^ k[i]);
	}
	}
	if (oddBytes > 0) {
	embeddedCipher.encryptBlock(register, 0, k, 0);
	for (i=0; i<oddBytes; i++) {
	register[i] = cipher[i+cipherOffset];
	plain[i+plainOffset]
	= (byte)(cipher[i+cipherOffset] ^ k[i]);
	}
	}
	} else {
	for (; loopCount > 0;
	plainOffset += numBytes, cipherOffset += numBytes,
	loopCount--) {
	embeddedCipher.encryptBlock(register, 0, k, 0);
	System.arraycopy(register, numBytes, register, 0, len);
	for (i=0; i<numBytes; i++) {
	register[i+len] = cipher[i+cipherOffset];
	plain[i+plainOffset]
	= (byte)(cipher[i+cipherOffset] ^ k[i]);
	}
	}
	if (oddBytes != 0) {
	embeddedCipher.encryptBlock(register, 0, k, 0);
	System.arraycopy(register, numBytes, register, 0, len);
	for (i=0; i<oddBytes; i++) {
	register[i+len] = cipher[i+cipherOffset];
	plain[i+plainOffset]
	= (byte)(cipher[i+cipherOffset] ^ k[i]);
	}
	}
	}
	return cipherLen;
	}
	}