/******************************************************************************
 * Copyright (c) 2000 The Legion Of The Bouncy Castle (http://www.bouncycastle.org)
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 ******************************************************************************/

package net.sourceforge.jtds.util;

/**
 * implementation of MD4 as RFC 1320 by R. Rivest, MIT Laboratory for
 * Computer Science and RSA Data Security, Inc.
 * <p>
 * <b>NOTE</b>: This algorithm is only included for backwards compatability
 * with legacy applications, it's not secure, don't use it for anything new!
 *
 * @version $Id: MD4Digest.java,v 1.2 2004/06/27 17:00:55 bheineman Exp $
 */
public class MD4Digest extends GeneralDigest {
    private static final int DIGEST_LENGTH = 16;

    //
    // round 1 left rotates
    //
    private static final int S11 = 3;
    private static final int S12 = 7;
    private static final int S13 = 11;
    private static final int S14 = 19;

    //
    // round 2 left rotates
    //
    private static final int S21 = 3;
    private static final int S22 = 5;
    private static final int S23 = 9;
    private static final int S24 = 13;

    //
    // round 3 left rotates
    //
    private static final int S31 = 3;
    private static final int S32 = 9;
    private static final int S33 = 11;
    private static final int S34 = 15;

    private int H1, H2, H3, H4;         // IV's

    private int[] X = new int[16];
    private int xOff;

    /**
     * Standard constructor
     */
    public MD4Digest() {
        reset();
    }

    /**
     * Copy constructor.  This will copy the state of the provided
     * message digest.
     */
    public MD4Digest(MD4Digest t) {
        super(t);

        H1 = t.H1;
        H2 = t.H2;
        H3 = t.H3;
        H4 = t.H4;

        System.arraycopy(t.X, 0, X, 0, t.X.length);
        xOff = t.xOff;
    }

    public String getAlgorithmName() {
        return "MD4";
    }

    public int getDigestSize() {
        return DIGEST_LENGTH;
    }

    protected void processWord(byte[] in, int inOff) {
        X[xOff++] = (in[inOff] & 0xff) | ((in[inOff + 1] & 0xff) << 8)
                    | ((in[inOff + 2] & 0xff) << 16) | ((in[inOff + 3] & 0xff) << 24);

        if (xOff == 16) {
            processBlock();
        }
    }

    protected void processLength(long bitLength) {
        if (xOff > 14) {
            processBlock();
        }

        X[14] = (int)(bitLength & 0xffffffff);
        X[15] = (int)(bitLength >>> 32);
    }

    private void unpackWord(int word, byte[] out, int outOff) {
        out[outOff]     = (byte)word;
        out[outOff + 1] = (byte)(word >>> 8);
        out[outOff + 2] = (byte)(word >>> 16);
        out[outOff + 3] = (byte)(word >>> 24);
    }

    public int doFinal(byte[] out, int outOff) {
        finish();

        unpackWord(H1, out, outOff);
        unpackWord(H2, out, outOff + 4);
        unpackWord(H3, out, outOff + 8);
        unpackWord(H4, out, outOff + 12);

        reset();

        return DIGEST_LENGTH;
    }

    /**
     * reset the chaining variables to the IV values.
     */
    public void reset() {
        super.reset();

        H1 = 0x67452301;
        H2 = 0xefcdab89;
        H3 = 0x98badcfe;
        H4 = 0x10325476;

        xOff = 0;

        for (int i = 0; i != X.length; i++) {
            X[i] = 0;
        }
    }

    /*
     * rotate int x left n bits.
     */
    private int rotateLeft(int x, int n) {
        return(x << n) | (x >>> (32 - n));
    }

    /*
     * F, G, H and I are the basic MD4 functions.
     */
    private int F(int u, int v, int w) {
        return(u & v) | (~u & w);
    }

    private int G(int u, int v, int w) {
        return(u & v) | (u & w) | (v & w);
    }

    private int H(int u, int v, int w) {
        return u ^ v ^ w;
    }

    protected void processBlock() {
        int a = H1;
        int b = H2;
        int c = H3;
        int d = H4;

        //
        // Round 1 - F cycle, 16 times.
        //
        a = rotateLeft((a + F(b, c, d) + X[ 0]), S11);
        d = rotateLeft((d + F(a, b, c) + X[ 1]), S12);
        c = rotateLeft((c + F(d, a, b) + X[ 2]), S13);
        b = rotateLeft((b + F(c, d, a) + X[ 3]), S14);
        a = rotateLeft((a + F(b, c, d) + X[ 4]), S11);
        d = rotateLeft((d + F(a, b, c) + X[ 5]), S12);
        c = rotateLeft((c + F(d, a, b) + X[ 6]), S13);
        b = rotateLeft((b + F(c, d, a) + X[ 7]), S14);
        a = rotateLeft((a + F(b, c, d) + X[ 8]), S11);
        d = rotateLeft((d + F(a, b, c) + X[ 9]), S12);
        c = rotateLeft((c + F(d, a, b) + X[10]), S13);
        b = rotateLeft((b + F(c, d, a) + X[11]), S14);
        a = rotateLeft((a + F(b, c, d) + X[12]), S11);
        d = rotateLeft((d + F(a, b, c) + X[13]), S12);
        c = rotateLeft((c + F(d, a, b) + X[14]), S13);
        b = rotateLeft((b + F(c, d, a) + X[15]), S14);

        //
        // Round 2 - G cycle, 16 times.
        //
        a = rotateLeft((a + G(b, c, d) + X[ 0] + 0x5a827999), S21);
        d = rotateLeft((d + G(a, b, c) + X[ 4] + 0x5a827999), S22);
        c = rotateLeft((c + G(d, a, b) + X[ 8] + 0x5a827999), S23);
        b = rotateLeft((b + G(c, d, a) + X[12] + 0x5a827999), S24);
        a = rotateLeft((a + G(b, c, d) + X[ 1] + 0x5a827999), S21);
        d = rotateLeft((d + G(a, b, c) + X[ 5] + 0x5a827999), S22);
        c = rotateLeft((c + G(d, a, b) + X[ 9] + 0x5a827999), S23);
        b = rotateLeft((b + G(c, d, a) + X[13] + 0x5a827999), S24);
        a = rotateLeft((a + G(b, c, d) + X[ 2] + 0x5a827999), S21);
        d = rotateLeft((d + G(a, b, c) + X[ 6] + 0x5a827999), S22);
        c = rotateLeft((c + G(d, a, b) + X[10] + 0x5a827999), S23);
        b = rotateLeft((b + G(c, d, a) + X[14] + 0x5a827999), S24);
        a = rotateLeft((a + G(b, c, d) + X[ 3] + 0x5a827999), S21);
        d = rotateLeft((d + G(a, b, c) + X[ 7] + 0x5a827999), S22);
        c = rotateLeft((c + G(d, a, b) + X[11] + 0x5a827999), S23);
        b = rotateLeft((b + G(c, d, a) + X[15] + 0x5a827999), S24);

        //
        // Round 3 - H cycle, 16 times.
        //
        a = rotateLeft((a + H(b, c, d) + X[ 0] + 0x6ed9eba1), S31);
        d = rotateLeft((d + H(a, b, c) + X[ 8] + 0x6ed9eba1), S32);
        c = rotateLeft((c + H(d, a, b) + X[ 4] + 0x6ed9eba1), S33);
        b = rotateLeft((b + H(c, d, a) + X[12] + 0x6ed9eba1), S34);
        a = rotateLeft((a + H(b, c, d) + X[ 2] + 0x6ed9eba1), S31);
        d = rotateLeft((d + H(a, b, c) + X[10] + 0x6ed9eba1), S32);
        c = rotateLeft((c + H(d, a, b) + X[ 6] + 0x6ed9eba1), S33);
        b = rotateLeft((b + H(c, d, a) + X[14] + 0x6ed9eba1), S34);
        a = rotateLeft((a + H(b, c, d) + X[ 1] + 0x6ed9eba1), S31);
        d = rotateLeft((d + H(a, b, c) + X[ 9] + 0x6ed9eba1), S32);
        c = rotateLeft((c + H(d, a, b) + X[ 5] + 0x6ed9eba1), S33);
        b = rotateLeft((b + H(c, d, a) + X[13] + 0x6ed9eba1), S34);
        a = rotateLeft((a + H(b, c, d) + X[ 3] + 0x6ed9eba1), S31);
        d = rotateLeft((d + H(a, b, c) + X[11] + 0x6ed9eba1), S32);
        c = rotateLeft((c + H(d, a, b) + X[ 7] + 0x6ed9eba1), S33);
        b = rotateLeft((b + H(c, d, a) + X[15] + 0x6ed9eba1), S34);

        H1 += a;
        H2 += b;
        H3 += c;
        H4 += d;

        //
        // reset the offset and clean out the word buffer.
        //
        xOff = 0;

        for (int i = 0; i != X.length; i++) {
            X[i] = 0;
        }
    }
}
