package gnu.crypto.hash;

// ----------------------------------------------------------------------------
// $Id: MD4.java,v 1.6 2005/10/06 04:24:14 rsdio Exp $
//
// Copyright (C) 2001, 2002, Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// GNU Crypto 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 for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING.  If not, write to the
//
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//    51 Franklin Street, Fifth Floor,
//    Boston, MA 02110-1301
//    USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
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//
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// you permission to link this library with independent modules to
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// for each linked independent module, the terms and conditions of the
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// library, you may extend this exception to your version of the
// library, but you are not obligated to do so.  If you do not wish to
// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------

import gnu.crypto.Registry;
import gnu.crypto.util.Util;

/**
 * <p>An implementation of Ron Rivest's MD4 message digest algorithm.</p>
 *
 * <p>MD4 was the precursor to the stronger {@link gnu.crypto.hash.MD5}
 * algorithm, and while not considered cryptograpically secure itself, MD4 is
 * in use in various applications. It is slightly faster than MD5.</p>
 *
 * <p>References:</p>
 *
 * <ol>
 *    <li>The <a href="http://www.ietf.org/rfc/rfc1320.txt">MD4</a>
 *    Message-Digest Algorithm.<br>
 *    R. Rivest.</li>
 * </ol>
 *
 * @version $Revision: 1.6 $
 * @author Casey Marshall (rsdio@metastatic.org)
 */
public class MD4 extends BaseHash {

   // Constants and variables
   // -------------------------------------------------------------------------

   /** An MD4 message digest is always 128-bits long, or 16 bytes. */
   private static final int DIGEST_LENGTH = 16;

   /** The MD4 algorithm operates on 512-bit blocks, or 64 bytes. */
   private static final int BLOCK_LENGTH = 64;

   private static final int A = 0x67452301;
   private static final int B = 0xefcdab89;
   private static final int C = 0x98badcfe;
   private static final int D = 0x10325476;

   /** The output of this message digest when no data has been input. */
   private static final String DIGEST0 = "31D6CFE0D16AE931B73C59D7E0C089C0";

   /** caches the result of the correctness test, once executed. */
   private static Boolean valid;

   private int a, b, c, d;

   // Constructor(s)
   // -------------------------------------------------------------------------

   /**
    * <p>Public constructor. Initializes the chaining variables, sets the byte
    * count to <code>0</code>, and creates a new block of <code>512</code> bits.
    * </p>
    */
   public MD4() {
      super(Registry.MD4_HASH, DIGEST_LENGTH, BLOCK_LENGTH);
   }

   /**
    * <p>Trivial private constructor for cloning purposes.</p>
    *
    * @param that the instance to clone.
    */
   private MD4(MD4 that) {
      this();

      this.a = that.a;
      this.b = that.b;
      this.c = that.c;
      this.d = that.d;
      this.count = that.count;
      this.buffer = (byte[]) that.buffer.clone();
   }

   // Class methods
   // -------------------------------------------------------------------------

   // Instance methods
   // -------------------------------------------------------------------------

   // java.lang.Cloneable interface implementation ----------------------------

   public Object clone() {
      return new MD4(this);
   }

   // Implementation of abstract methods in BashHash --------------------------

   protected byte[] getResult() {
      byte[] digest = {
         (byte) a, (byte) (a >>> 8), (byte) (a >>> 16), (byte) (a >>> 24),
         (byte) b, (byte) (b >>> 8), (byte) (b >>> 16), (byte) (b >>> 24),
         (byte) c, (byte) (c >>> 8), (byte) (c >>> 16), (byte) (c >>> 24),
         (byte) d, (byte) (d >>> 8), (byte) (d >>> 16), (byte) (d >>> 24)
      };
      return digest;
   }

   protected void resetContext() {
      a = A; b = B;
      c = C; d = D;
   }

   public boolean selfTest() {
      if (valid == null) {
         valid = new Boolean(
               DIGEST0.equals(Util.toString(new MD4().digest())));
      }
      return valid.booleanValue();
   }

   protected byte[] padBuffer() {
      int n = (int) (count % BLOCK_LENGTH);
      int padding = (n < 56) ? (56 - n) : (120 - n);
      byte[] pad = new byte[padding + 8];

      pad[0] = (byte) 0x80;
      long bits = count << 3;
      pad[padding++] = (byte)  bits;
      pad[padding++] = (byte) (bits >>>  8);
      pad[padding++] = (byte) (bits >>> 16);
      pad[padding++] = (byte) (bits >>> 24);
      pad[padding++] = (byte) (bits >>> 32);
      pad[padding++] = (byte) (bits >>> 40);
      pad[padding++] = (byte) (bits >>> 48);
      pad[padding  ] = (byte) (bits >>> 56);

      return pad;
   }

   protected void transform(byte[] in, int i) {
      int X0 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X1 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X2 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X3 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X4 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X5 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X6 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X7 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X8 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X9 =  (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X10 = (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X11 = (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X12 = (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X13 = (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X14 = (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i++] << 24;
      int X15 = (in[i++] & 0xFF) | (in[i++] & 0xFF) << 8 | (in[i++] & 0xFF) << 16 | in[i  ] << 24;
   
      int aa, bb, cc, dd;

      aa = a;  bb = b;  cc = c;  dd = d;

      aa += ((bb & cc) | ((~bb) & dd)) + X0;
      aa = aa <<  3 | aa >>> -3;
      dd += ((aa & bb) | ((~aa) & cc)) + X1;
      dd = dd <<  7 | dd >>> -7;
      cc += ((dd & aa) | ((~dd) & bb)) + X2;
      cc = cc << 11 | cc >>> -11;
      bb += ((cc & dd) | ((~cc) & aa)) + X3;
      bb = bb << 19 | bb >>> -19;
      aa += ((bb & cc) | ((~bb) & dd)) + X4;
      aa = aa <<  3 | aa >>> -3;
      dd += ((aa & bb) | ((~aa) & cc)) + X5;
      dd = dd <<  7 | dd >>> -7;
      cc += ((dd & aa) | ((~dd) & bb)) + X6;
      cc = cc << 11 | cc >>> -11;
      bb += ((cc & dd) | ((~cc) & aa)) + X7;
      bb = bb << 19 | bb >>> -19;
      aa += ((bb & cc) | ((~bb) & dd)) + X8;
      aa = aa <<  3 | aa >>> -3;
      dd += ((aa & bb) | ((~aa) & cc)) + X9;
      dd = dd <<  7 | dd >>> -7;
      cc += ((dd & aa) | ((~dd) & bb)) + X10;
      cc = cc << 11 | cc >>> -11;
      bb += ((cc & dd) | ((~cc) & aa)) + X11;
      bb = bb << 19 | bb >>> -19;
      aa += ((bb & cc) | ((~bb) & dd)) + X12;
      aa = aa <<  3 | aa >>> -3;
      dd += ((aa & bb) | ((~aa) & cc)) + X13;
      dd = dd <<  7 | dd >>> -7;
      cc += ((dd & aa) | ((~dd) & bb)) + X14;
      cc = cc << 11 | cc >>> -11;
      bb += ((cc & dd) | ((~cc) & aa)) + X15;
      bb = bb << 19 | bb >>> -19;

      aa += ((bb & (cc | dd)) | (cc & dd)) + X0 + 0x5a827999;
      aa = aa <<  3 | aa >>> -3;
      dd += ((aa & (bb | cc)) | (bb & cc)) + X4 + 0x5a827999;
      dd = dd <<  5 | dd >>> -5;
      cc += ((dd & (aa | bb)) | (aa & bb)) + X8 + 0x5a827999;
      cc = cc <<  9 | cc >>> -9;
      bb += ((cc & (dd | aa)) | (dd & aa)) + X12 + 0x5a827999;
      bb = bb << 13 | bb >>> -13;
      aa += ((bb & (cc | dd)) | (cc & dd)) + X1 + 0x5a827999;
      aa = aa <<  3 | aa >>> -3;
      dd += ((aa & (bb | cc)) | (bb & cc)) + X5 + 0x5a827999;
      dd = dd <<  5 | dd >>> -5;
      cc += ((dd & (aa | bb)) | (aa & bb)) + X9 + 0x5a827999;
      cc = cc <<  9 | cc >>> -9;
      bb += ((cc & (dd | aa)) | (dd & aa)) + X13 + 0x5a827999;
      bb = bb << 13 | bb >>> -13;
      aa += ((bb & (cc | dd)) | (cc & dd)) + X2 + 0x5a827999;
      aa = aa <<  3 | aa >>> -3;
      dd += ((aa & (bb | cc)) | (bb & cc)) + X6 + 0x5a827999;
      dd = dd <<  5 | dd >>> -5;
      cc += ((dd & (aa | bb)) | (aa & bb)) + X10 + 0x5a827999;
      cc = cc <<  9 | cc >>> -9;
      bb += ((cc & (dd | aa)) | (dd & aa)) + X14 + 0x5a827999;
      bb = bb << 13 | bb >>> -13;
      aa += ((bb & (cc | dd)) | (cc & dd)) + X3 + 0x5a827999;
      aa = aa <<  3 | aa >>> -3;
      dd += ((aa & (bb | cc)) | (bb & cc)) + X7 + 0x5a827999;
      dd = dd <<  5 | dd >>> -5;
      cc += ((dd & (aa | bb)) | (aa & bb)) + X11 + 0x5a827999;
      cc = cc <<  9 | cc >>> -9;
      bb += ((cc & (dd | aa)) | (dd & aa)) + X15 + 0x5a827999;
      bb = bb << 13 | bb >>> -13;

      aa += (bb ^ cc ^ dd) + X0 + 0x6ed9eba1;
      aa = aa <<  3 | aa >>> -3;
      dd += (aa ^ bb ^ cc) + X8 + 0x6ed9eba1;
      dd = dd <<  9 | dd >>> -9;
      cc += (dd ^ aa ^ bb) + X4 + 0x6ed9eba1;
      cc = cc << 11 | cc >>> -11;
      bb += (cc ^ dd ^ aa) + X12 + 0x6ed9eba1;
      bb = bb << 15 | bb >>> -15;
      aa += (bb ^ cc ^ dd) + X2 + 0x6ed9eba1;
      aa = aa <<  3 | aa >>> -3;
      dd += (aa ^ bb ^ cc) + X10 + 0x6ed9eba1;
      dd = dd <<  9 | dd >>> -9;
      cc += (dd ^ aa ^ bb) + X6 + 0x6ed9eba1;
      cc = cc << 11 | cc >>> -11;
      bb += (cc ^ dd ^ aa) + X14 + 0x6ed9eba1;
      bb = bb << 15 | bb >>> -15;
      aa += (bb ^ cc ^ dd) + X1 + 0x6ed9eba1;
      aa = aa <<  3 | aa >>> -3;
      dd += (aa ^ bb ^ cc) + X9 + 0x6ed9eba1;
      dd = dd <<  9 | dd >>> -9;
      cc += (dd ^ aa ^ bb) + X5 + 0x6ed9eba1;
      cc = cc << 11 | cc >>> -11;
      bb += (cc ^ dd ^ aa) + X13 + 0x6ed9eba1;
      bb = bb << 15 | bb >>> -15;
      aa += (bb ^ cc ^ dd) + X3 + 0x6ed9eba1;
      aa = aa <<  3 | aa >>> -3;
      dd += (aa ^ bb ^ cc) + X11 + 0x6ed9eba1;
      dd = dd <<  9 | dd >>> -9;
      cc += (dd ^ aa ^ bb) + X7 + 0x6ed9eba1;
      cc = cc << 11 | cc >>> -11;
      bb += (cc ^ dd ^ aa) + X15 + 0x6ed9eba1;
      bb = bb << 15 | bb >>> -15;

      a += aa; b += bb; c += cc; d += dd;
   }
}
