// $Id: FeedbackMode.java,v 1.1.1.1 2002/08/27 12:32:12 grosbois Exp $//// $Log: FeedbackMode.java,v $// Revision 1.1.1.1  2002/08/27 12:32:12  grosbois// Add cryptix 3.2//// Revision 1.5  2000/08/17 11:40:58  edwin// java.* -> xjava.*//// Revision 1.4  1997/11/20 19:39:32  hopwood// + cryptix.util.* name changes.//// Revision 1.3  1997/11/07 05:53:25  raif// *** empty log message ***//// Revision 1.2  1997/11/05 08:01:56  raif// *** empty log message ***//// Revision 1.1.1.1  1997/11/03 22:36:56  hopwood// + Imported to CVS (tagged as 'start').//// Revision 0.1.0.1  1997/08/28  David Hopwood// + Made this class implement SymmetricCipher.//// Revision 0.1.0.0  1997/08/08  David Hopwood// + Original version, split from java.security.Mode.// + Removed setInitializationVector() with no arguments (zero IVs//   are not a good idea in general).//// $Endlog$/* * Copyright (c) 1997 Systemics Ltd * on behalf of the Cryptix Development Team.  All rights reserved. */package cryptix.provider.mode;import xjava.security.Cipher;import xjava.security.FeedbackCipher;import java.security.InvalidParameterException;import xjava.security.Mode;import xjava.security.SymmetricCipher;/** * <samp>FeedbackMode</samp> is used to provide the functionality of an * encryption mode, such as CBC, CFB, or OFB, that works as a feedback * cipher, where the size of the IV and feedback buffer are equal to the * cipher's block size. * <p> * It is internal to Cryptix, and not intended to be used directly by * applications. * <p> * <b>Copyright</b> &copy; 1997 * <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 */abstract class FeedbackModeextends Modeimplements FeedbackCipher, SymmetricCipher{// Variables//...........................................................................    /** Value of the current feedback register/queue/buffer. */    protected byte[] ivBlock;    /** Value of the IV at initialisation phase as supplied by user. */    protected byte[] ivStart;    /** Index into the ivBlock. */    protected int currentByte;    /** Size of the feedback register/queue/buffer. */    protected int length;// Constructor//...........................................................................        /**     * Constructor for a Mode. This constructor is only for use      * by subclasses, which should pass the correct arguments to convey      * their behaviour to the superclass.  Applications typically do     * not use Mode classes directly; they should call one of the      * <code><a href="java.security.Cipher.html#getInstance">Cipher.getInstance</a></code>     * factory methods instead.     *     * @param  implBuffering    if true, this argument indicates that data     *                          will be passed from update/crypt to     *                          engineUpdate/engineCrypt without modification.     * @param  implPadding      if true, this argument indicates that the     *                          implementation can perform padding, and that     *                          the engineCrypt method will be called when     *                          padding is required.     * @param  provider         the name of the provider of the underlying     *                          cryptographic engine.     * @exception NullPointerException if provider == null     */    protected FeedbackMode(boolean implBuffering, boolean implPadding, String provider) {        super(implBuffering, implPadding, provider);    }// Own methods//...........................................................................    /**     * <b>SPI</b>: Sets the underlying cipher.     * <p>     * For example, to create an IDEA cipher in CBC mode, the cipher     * for "IDEA" would be passed to the mode for "CBC" using     * this method. It is called once, immediately after the mode     * object is constructed.     * <p>     * Subclasses that override this method (to do initialization that     * depends on the cipher being set) should call     * <code>super.engineSetCipher(cipher)</code> first.     *     * @param  cipher   the underlying cipher object     * @exception NullPointerException if cipher == null     */    protected void engineSetCipher(Cipher cipher) {        super.engineSetCipher(cipher);        length = cipher.blockSize();        ivStart = null;        ivBlock = new byte[length];        currentByte = 0;    }// FeedbackCipher default implementations//...........................................................................    /**     * Sets the initialization vector.     * <p>     * Note: in JavaSoft's version of JCE, this method may only be     * called when the cipher is in the <code>UNINITIALIZED</code> state.     * In IJCE that is relaxed to also allow it to be called after     * <code>initEncrypt</code>/<code>initDecrypt</code>, but before the     * first call to <code>update</code> or <code>crypt</code>, provided     * that the IV is not set twice.     *     * @param  iv   the initialization vector.     * @exception InvalidParameterException if the initialization vector     *              is of the wrong length or has already been set.     */    public void setInitializationVector(byte[] iv)    throws InvalidParameterException {        if (ivStart != null)            throw new InvalidParameterException(                getMode() + ": Initialization vector is already set");        if (iv.length != length)            throw new InvalidParameterException(                getMode() + ": Initialization vector length = " + iv.length +                ", should be " + length);        ivStart = (byte[]) (iv.clone());        ivBlock = (byte[]) (ivStart.clone());        currentByte = length;    }    /**     * Gets a copy of the starting initialization vector. It will     * return null if the initialization vector has not been set.     *     * @return a copy of the initialization vector for this cipher object.     */    public byte[] getInitializationVector() {        return (ivStart == null) ? null : (byte[]) (ivStart.clone());    }    /**     * Returns the size of the initialization vector expected by     * <code>setInitializationVector</code>. For this class, that is     * the block size of the underlying cipher.     *     * @return the required size of the argument to     *         <code>setInitializationVector</code>.     */    public int getInitializationVectorLength() { return length; }}