cast5.java

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// $Id: CAST5.java,v 1.1.1.1 2002/08/27 12:32:09 grosbois Exp $
//
// $Log: CAST5.java,v $
// Revision 1.1.1.1  2002/08/27 12:32:09  grosbois
// Add cryptix 3.2
//
// Revision 1.6  2000/08/17 11:40:51  edwin
// java.* -> xjava.*
//
// Revision 1.5  1998/01/21 22:16:18  iang
// added URL to RFC-2144.
//
// Revision 1.4  1997/12/30 11:09:50  raif
// *** empty log message ***
//
// Revision 1.3.1  1997/12/30  raif
// + further performance optimisation based on Peter Hjelt
//   (MXV) ([e-mail]) tip of unfolding the session
//   key arrays into individual native java type objects.
//
// Revision 1.3  1997/11/29 04:42:55  hopwood
// + Changes to engineUpdate method.
//
// Revision 1.2  1997/11/20 19:31:40  hopwood
// + cryptix.util.* name changes.
//
// Revision 1.1.1.1  1997/11/03 22:36:56  hopwood
// + Imported to CVS (tagged as 'start').
//
// Revision 0.1.1.0  1997/08/18  David Hopwood
// + Tightened some of the access specifiers (e.g. SPI methods were public,
//   and are now protected).
// + Ensured that this class is final, and added a comment that this is for
//   security reasons.
//   If it were not final, some VMs have a bug that would allow a subclass
//   that implements Cloneable to call Object's or Cipher's clone() method
//   using invokenonvirtual, which would duplicate the pointer to the native
//   state. Then calling finalize() on the original and using the clone (for
//   example) would result in freed memory being written to :-(.
// + Required native code version is 2.3.
//
// Revision 0.1.0.1  1997/07/16  David Hopwood
// + Cosmetic changes.
//
// Revision 0.1.0.0  1997/07/15  R. Naffah
// + Original version.
//
// $Endlog$
/*
 * Copyright (c) 1997 Systemics Ltd
 * on behalf of the Cryptix Development Team.  All rights reserved.
 */

package cryptix.provider.cipher;

import cryptix.util.core.Debug;
import cryptix.CryptixException;
import cryptix.util.core.ArrayUtil;
import cryptix.util.core.Hex;
import cryptix.provider.key.RawSecretKey;

import java.io.PrintWriter;
import xjava.security.Cipher;
import java.security.Key;
import java.security.KeyException;
import java.security.Security;
import xjava.security.SymmetricCipher;

/** 
 * A subclass of Cipher to implement the CAST5 (a.k.a. CAST-128) algorithm in
 * Java, as per RFC 2144 dated May 1997.
 * <p>
 * In this RFC, Carlisle Adams (the CA in CAST, ST standing for Stafford
 * Tavares) describes CAST5 as:
 * <p>
 * <blockquote>
 *    "...a DES-like Substitution-Permutation Network (SPN) cryptosystem which
 *    appears to have good resistance to differential cryptanalysis, linear
 *    cryptanalysis, and related-key cryptanalysis. This cipher also possesses
 *    a number of other desirable cryptographic properties, including avalanche,
 *    Strict Avalanche Criterion (SAC), Bit Independence Criterion (BIC), no
 *    complementation property, and an absence of weak and semi-weak keys."
 * </blockquote>
 * <p>
 * CAST5 is a symmetric block cipher with a block-size of 8 bytes and
 * a variable key-size of up to 128 bits. Its authors and their employer
 * (Entrust Technologies, a Nortel majority-owned company) made it available
 * worldwide on a royalty-free basis for commercial and non-commercial uses.
 * <p>
 * The CAST5 encryption algorithm has been designed to allow a key size
 * that can vary from 40 bits to 128 bits, in 8-bit increments (that is, the
 * allowable key sizes are 40, 48, 56, 64, ..., 112, 120, and 128 bits. For
 * variable keysize operation, the specification is as follows:
 * <ol>
 *   <li> For key sizes up to and including 80 bits (i.e., 40, 48, 56, 64, 72,
 *        and 80 bits), the algorithm is exactly as specified but uses 12 rounds
 *        instead of 16;
 *   <li> For key sizes greater than 80 bits, the algorithm uses the full 16
 *        rounds;
 *   <li> For key sizes less than 128 bits, the key is padded with zero bytes
 *        (in the rightmost, or least significant, positions) out to 128 bits
 *        (since the CAST5 key schedule assumes an input key of 128 bits).
 * </ol>
 * <p>
 * <b>References:</b>
 * <ol>
 *   <li> Carlisle Adams,
 *        <a href="http://rfc.fh-koeln.de/rfc/html/rfc2144.html">
 *        RFC 2144</a>, May 1997.
 * </ol>
 * <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  Raif S. Naffah
 * @since   Cryptix 2.2.2
 */
public final class CAST5 // must be final for security reasons
extends Cipher
implements SymmetricCipher
{

// Debugging methods and vars.
//...........................................................................

    private static final boolean DEBUG = Debug.GLOBAL_DEBUG;
    private static final boolean DEBUG_SLOW = Debug.GLOBAL_DEBUG_SLOW;
    private static final int debuglevel = DEBUG ? Debug.getLevel("CAST5") : 0;
    private static final PrintWriter err = DEBUG ? Debug.getOutput() : null;
    private static void debug(String s) { err.println("CAST5: " + s); }


// Native library linking methods and vars.
//...........................................................................

    private static NativeLink linkStatus = new NativeLink("CAST5", 2, 3);

    /**
     * Gets an object representing the native linking status of this class.
     */
    public static cryptix.util.core.LinkStatus getLinkStatus() { return linkStatus; }

    /**
     * The native reference to the current native key schedule
     * structure. Defaults to 0 but is set by native code after a
     * successful call to native_init().
     * <p>
     * IMPORTANT: Do not change the name of this variable without
     * duplicating the same in the native code.
     */
    private long native_cookie;

    /**
     * This object must be synchronized on while calling any native instance
     * method. It is null if the native code is not being used (e.g. the
     * library did not load successfully, or the user disabled its use in
     * the properties file).
     */
    private Object native_lock; // defaults to null

    private void link() {
        synchronized(linkStatus) {
            try {
                if (linkStatus.attemptLoad()) {
                    linkStatus.checkVersion(getLibMajorVersion(), getLibMinorVersion());
                    linkStatus.check(native_clinit());
                }
                if (linkStatus.useNative()) {
                    linkStatus.check(native_init());
                    native_lock = new Object();
                }
            } catch (UnsatisfiedLinkError e) {
                linkStatus.fail(e);
if (DEBUG && debuglevel > 2) debug(e.getMessage());
            }
if (DEBUG && debuglevel > 2) debug("Using native library? " + (native_lock != null));
        }
    }


// Native support API
//...........................................................................

    // The methods that get the library version.
    private native static int getLibMajorVersion();
    private native static int getLibMinorVersion();

    /**
     * Static initialization and self-test method for the native code.
     *
     * @return a string if an error occurred or null otherwise.
     */
    private native String native_clinit();

    /**
     * Initializes the native state for this cipher object and allocates
     * needed native storage for the internal key schedule. A reference
     * to the newly allocated space, if successful, is stored in the
     * instance variable <code>native_cookie</code>.
     *
     * @return a string if an error occurred or null otherwise.
     */
    private native String native_init();

    /**
     * This function expands the user key to an internal form.
     *
     * @param  cookie   a valid reference to the native key structure. This
     *                  value is set by the native library upon return from
     *                  native_init() (see link() method at the top).
     * @param  userKey  a byte array representing the user key
     * @return an error String, or null if there was no error
     */
    private native String native_ks(long cookie, byte[] userKey);

    /**
     * Encrypts/decrypts a data block.
     * <p>
     * FUTURE: possibly change this to be able to process more than one block,
     * to reduce native method call overhead.
     * <p>
     * SECURITY: the caller <strong>must</strong> ensure that:
     * <ul>
     *   <li> <code>in != null</code>
     *   <li> <code>out != null</code>
     *   <li> <code>inOffset >= 0</code>
     *   <li> <code>(long)inOffset + BLOCK_LENGTH <= in.length</code>
     *   <li> <code>outOffset >= 0</code>
     *   <li> <code>(long)outOffset + BLOCK_LENGTH <= out.length</code>
     * </ul>
     *
     * @param  cookie       a valid reference to the native key structure. This
     *                      value is set by the native library upon return from
     *                      native_init() (see link() method at the top).
     * @param  in           input array containing data to encrypt or decrypt
     *                      depending on the value of the encrypt boolean parameter.
     * @param  inOffset     index of where we should start reading from input.
     * @param  out          output array containing data decrypted or encrypted
     *                      depending on the value of the encrypt boolean parameter.
     * @param  outOffset    index of where we should start writing to output.
     * @param  encrypt      if true then encrypt, otherwise decrypt.
     * @return the number of bytes crypted (always BLOCK_LENGTH) or 0 if an error
     *                      occurred.
     */
    private native int native_crypt (long cookie, byte[] in, int inOffset,
                                     byte[] out, int outOffset, boolean encrypt);

    /**
     * Finalizes the native state for this object.
     *
     * @return a string if an error occurred or null otherwise.
     */
    private native String native_finalize();


// Variables and constants
//............................................................................

    // CAST5 S-boxes
    private static final int[]
        S1 = {