// $Id: CBC.java,v 1.1.1.1 2002/08/27 12:32:12 grosbois Exp $//// $Log: CBC.java,v $// Revision 1.1.1.1  2002/08/27 12:32:12  grosbois// Add cryptix 3.2//// Revision 1.7  2000/08/17 11:40:57  edwin// java.* -> xjava.*//// Revision 1.6  1998/04/02 01:42:01  raif// *** empty log message ***//// Revision 1.5.1  1998/04/02  raif// + added Gertjan van Oosten <gertjan@West.NL> bug correction//   in the engineUpdate/DECRYPT method/case.// + removed dead code.// + cosmetics.//// Revision 1.5  1997/12/09 05:14:36  raif// *** empty log message ***//// Revision 1.4  1997/11/20 19:39:31  hopwood// + cryptix.util.* name changes.//// Revision 1.3.1  1997/11/16  David Hopwood// + Removed commented-out code (since we will be using FeedbackMode//   permanently now).// + Fixed imports.// + FIXME: engineUpdate incorrectly assumes only one block of input.//// Revision 1.3  1997/11/07 05:53:25  raif// *** empty log message ***//// Revision 1.2  1997/11/05 08:01:56  raif// + Renamed temp to xorBlock.// + Call cipher.update instead of cipher.crypt.// + Fixed the decrypt bug.// + Added all the fixes that date back from Aug/97.//// Revision 1.1.1.1  1997/11/03 22:36:56  hopwood// + Imported to CVS (tagged as 'start').//// $Endlog$/* * Copyright (c) 1997, 1998 Systemics Ltd on behalf of * the Cryptix Development Team.  All rights reserved. */package cryptix.provider.mode;import cryptix.CryptixException;import xjava.security.Cipher;import java.security.Key;import java.security.KeyException;import java.security.InvalidParameterException;import xjava.security.IllegalBlockSizeException;/** * Implements a block cipher in CBC mode. The block size is the same as * that of the underlying cipher. * <p> * <b>References:</b> * <ol> *   <li> <a href="mailto:schneier@counterpane.com">Bruce Schneier</a>, *        "Section 9.3 Cipher Block Chaining Mode," and "Section 9.11 Choosing a Cipher Mode," *        <cite>Applied Cryptography, 2nd edition</cite>, *        John Wiley &amp; Sons, 1996.<p> *   <li> <samp>sci.crypt</samp> FAQ, "Part 5: Product Ciphers," *        <a href="ftp://ftp.rtfm.mit.edu/pub/usenet/news.answers/cryptography-faq/part05"> *        ftp://ftp.rtfm.mit.edu/pub/usenet/news.answers/cryptography-faq/part05</a>.<p> *   <li> National Bureau of Standards (now NIST), *        "DES Modes of Operation," *        <cite>NBS FIPS PUB 81</cite>, *        U.S. Department of Commerce, December 1980.</ol><p> * * <b>Copyright</b> &copy; 1997, 1998 * <a href="http://www.systemics.com/">Systemics Ltd</a> on behalf of the * <a href="http://www.systemics.com/docs/cryptix/">Cryptix Development Team</a>. * <br>All rights reserved.<p> * * <b>$Revision: 1.1.1.1 $</b> * @author David Hopwood * @author Raif S. Naffah * @since  Cryptix 2.2.2 */public class CBCextends FeedbackMode{// Variables//...........................................................................    /**     * Temporary buffer to hold input bytes when there's not enough of     * them to cipher.     */    protected byte[] xorBlock;// Constructors//...........................................................................    /**     * Constructs a CBC cipher, assuming that the IV will be provided     * via <code>setInitializationVector</code>.     * <p>     * The IV value should be random, but unlike     * <a href=cryptix.provider.mode.CFB.html>CFB</a> mode, it is not     * absolutely required to be unique.     */    public CBC() { super(false, false, "Cryptix"); }    /**     * Constructs a CBC cipher, assuming that the IV will be provided     * via <code>setInitializationVector</code>.     * See the previous constructor for more details.     *     * @param  cipher   the cipher object to use in CBC mode.     * @exception NullPointerException if cipher == null     * @exception IllegalBlockSizeException if cipher.getPlaintextBlockSize() !=     *                  cipher.getCiphertextBlockSize()     */    public CBC (Cipher cipher) {        this();        engineSetCipher(cipher);    }    /**     * Constructs a CBC cipher, using an initialization vector     * provided in the constructor.     * <p>     * For CBC mode the IV value should be random, but unlike     * <a href=cryptix.security.CFB.html>CFB</a> mode, it is not     * absolutely required to be unique.     *     * @param  cipher   the block cipher to use     * @param  iv       the initial value for the shift register (IV)     * @exception NullPointerException if cipher == null     */    public CBC (Cipher cipher, byte[] iv) {        this(cipher);        setInitializationVector(iv);    }// FeedbackMode and Mode methods//...........................................................................    protected void engineSetCipher (Cipher cipher) {        super.engineSetCipher(cipher);        xorBlock = new byte[length];    }// Cipher methods//...........................................................................    protected int engineBlockSize() { return length; }    protected void engineInitEncrypt (Key newkey) throws KeyException {        cipher.initEncrypt(newkey);        if (ivStart != null)            System.arraycopy(ivStart, 0, ivBlock, 0, length);    }    protected void engineInitDecrypt (Key newkey) throws KeyException {        cipher.initDecrypt(newkey);        if (ivStart != null)            System.arraycopy(ivStart, 0, ivBlock, 0, length);    }    /**     * <b>SPI</b>: This is the main engine method for updating data.     * It may be called with any size of input.     * <p>     * <code>in</code> and <code>out</code> may be the same array, and the     * input and output regions may overlap.     *     * @param in        the input data.     * @param inOffset  the offset into <code>in</code> specifying where     *                  the data starts.     * @param inLen     the length of the subarray.     * @param out       the output array.     * @param outOffset the offset indicating where to start writing into     *                  the <code>out</code> array.     * @return the number of bytes written.     */    protected int engineUpdate (byte[] in, int inOffset, int inLen,                                byte[] out, int outOffset) {        if (ivBlock == null)            throw new InvalidParameterException("CBC: IV is not set");        switch (getState()) {            case ENCRYPT:                for (int i = 0; i < inLen; )                    ivBlock[i++] ^= in[inOffset++];                cipher.update(ivBlock, 0, inLen, ivBlock, 0);                System.arraycopy(ivBlock, 0, out, outOffset, inLen);                break;            case DECRYPT:                byte[] ivTmp = new byte[inLen];                System.arraycopy(in, inOffset, ivTmp, 0, inLen);                cipher.update(in, inOffset, inLen, xorBlock, 0);                for (int i = 0; i < inLen; i++)                    out[i+outOffset] = (byte) (xorBlock[i] ^ ivBlock[i]);                System.arraycopy(ivTmp, 0, ivBlock, 0, inLen);                ivTmp = null;                break;            default:                throw new CryptixException("CBC: Cipher not initialized");        }        return inLen;    }}