/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.security.provider;

import java.security.*;

import static sun.security.provider.ByteArrayAccess.*;

/**

 * The MD4 class is used to compute an MD4 message digest over a given

 * buffer of bytes. It is an implementation of the RSA Data Security Inc

 * MD4 algorithim as described in internet RFC 1320.

 *

 * <p>The MD4 algorithm is very weak and should not be used unless it is

 * unavoidable. Therefore, it is not registered in our standard providers. To

 * obtain an implementation, call the static getInstance() method in this

 * class.

 *

 * @author      Andreas Sterbenz

 */

public final class MD4 extends DigestBase {

    // state of this object

    private final int[] state;

    // temporary buffer, used by implCompress()

    private final int[] x;

    // rotation constants

    private static final int S11 = 3;

    private static final int S12 = 7;

    private static final int S13 = 11;

    private static final int S14 = 19;

    private static final int S21 = 3;

    private static final int S22 = 5;

    private static final int S23 = 9;

    private static final int S24 = 13;

    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 final static Provider md4Provider;

    static {

        AccessController.doPrivileged(new PrivilegedAction<Void>() {

            public Void run() {

                md4Provider.put("MessageDigest.MD4", "sun.security.provider.MD4");

                return null;

            }

        });

    }

    public static MessageDigest getInstance() {

        try {

            return MessageDigest.getInstance("MD4", md4Provider);

        } catch (NoSuchAlgorithmException e) {

            // should never occur

            throw new ProviderException(e);

        }

    }

    // Standard constructor, creates a new MD4 instance.

    public MD4() {

        super("MD4", 16, 64);

        state = new int[4];

        x = new int[16];

        implReset();

    }

    // Cloning constructor

    private MD4(MD4 base) {

        super(base);

        this.state = base.state.clone();

        this.x = new int[16];

    }

    // clone this object

    public Object clone() {

        return new MD4(this);

    }

    /**

     * Reset the state of this object.

     */

    void implReset() {

        // Load magic initialization constants.

        state[0] = 0x67452301;

        state[1] = 0xefcdab89;

        state[2] = 0x98badcfe;

        state[3] = 0x10325476;

    }

    /**

     * Perform the final computations, any buffered bytes are added

     * to the digest, the count is added to the digest, and the resulting

     * digest is stored.

     */

    void implDigest(byte[] out, int ofs) {

        long bitsProcessed = bytesProcessed << 3;

        int index = (int)bytesProcessed & 0x3f;

        int padLen = (index < 56) ? (56 - index) : (120 - index);

        engineUpdate(padding, 0, padLen);

        i2bLittle4((int)bitsProcessed, buffer, 56);

        i2bLittle4((int)(bitsProcessed >>> 32), buffer, 60);

        implCompress(buffer, 0);

        i2bLittle(state, 0, out, ofs, 16);

    }

    private static int FF(int a, int b, int c, int d, int x, int s) {

        a += ((b & c) | ((~b) & d)) + x;

        return ((a << s) | (a >>> (32 - s)));

    }

    private static int GG(int a, int b, int c, int d, int x, int s) {

        a += ((b & c) | (b & d) | (c & d)) + x + 0x5a827999;

        return ((a << s) | (a >>> (32 - s)));

    }

    private static int HH(int a, int b, int c, int d, int x, int s) {

        a += ((b ^ c) ^ d) + x + 0x6ed9eba1;

        return ((a << s) | (a >>> (32 - s)));

    }

    /**

     * This is where the functions come together as the generic MD4

     * transformation operation. It consumes sixteen

     * bytes from the buffer, beginning at the specified offset.

     */

    void implCompress(byte[] buf, int ofs) {

        b2iLittle64(buf, ofs, x);

        int a = state[0];

        int b = state[1];

        int c = state[2];

        int d = state[3];

        /* Round 1 */

        a = FF (a, b, c, d, x[ 0], S11); /* 1 */

        d = FF (d, a, b, c, x[ 1], S12); /* 2 */

        c = FF (c, d, a, b, x[ 2], S13); /* 3 */

        b = FF (b, c, d, a, x[ 3], S14); /* 4 */

        a = FF (a, b, c, d, x[ 4], S11); /* 5 */

        d = FF (d, a, b, c, x[ 5], S12); /* 6 */

        c = FF (c, d, a, b, x[ 6], S13); /* 7 */

        b = FF (b, c, d, a, x[ 7], S14); /* 8 */

        a = FF (a, b, c, d, x[ 8], S11); /* 9 */

        d = FF (d, a, b, c, x[ 9], S12); /* 10 */

        c = FF (c, d, a, b, x[10], S13); /* 11 */

        b = FF (b, c, d, a, x[11], S14); /* 12 */

        a = FF (a, b, c, d, x[12], S11); /* 13 */

        d = FF (d, a, b, c, x[13], S12); /* 14 */

        c = FF (c, d, a, b, x[14], S13); /* 15 */

        b = FF (b, c, d, a, x[15], S14); /* 16 */

        /* Round 2 */

        a = GG (a, b, c, d, x[ 0], S21); /* 17 */

        d = GG (d, a, b, c, x[ 4], S22); /* 18 */

        c = GG (c, d, a, b, x[ 8], S23); /* 19 */

        b = GG (b, c, d, a, x[12], S24); /* 20 */

        a = GG (a, b, c, d, x[ 1], S21); /* 21 */

        d = GG (d, a, b, c, x[ 5], S22); /* 22 */

        c = GG (c, d, a, b, x[ 9], S23); /* 23 */

        b = GG (b, c, d, a, x[13], S24); /* 24 */

        a = GG (a, b, c, d, x[ 2], S21); /* 25 */

        d = GG (d, a, b, c, x[ 6], S22); /* 26 */

        c = GG (c, d, a, b, x[10], S23); /* 27 */

        b = GG (b, c, d, a, x[14], S24); /* 28 */

        a = GG (a, b, c, d, x[ 3], S21); /* 29 */

        d = GG (d, a, b, c, x[ 7], S22); /* 30 */

        c = GG (c, d, a, b, x[11], S23); /* 31 */

        b = GG (b, c, d, a, x[15], S24); /* 32 */

        /* Round 3 */

        a = HH (a, b, c, d, x[ 0], S31); /* 33 */

        d = HH (d, a, b, c, x[ 8], S32); /* 34 */

        c = HH (c, d, a, b, x[ 4], S33); /* 35 */

        b = HH (b, c, d, a, x[12], S34); /* 36 */

        a = HH (a, b, c, d, x[ 2], S31); /* 37 */

        d = HH (d, a, b, c, x[10], S32); /* 38 */

        c = HH (c, d, a, b, x[ 6], S33); /* 39 */

        b = HH (b, c, d, a, x[14], S34); /* 40 */

        a = HH (a, b, c, d, x[ 1], S31); /* 41 */

        d = HH (d, a, b, c, x[ 9], S32); /* 42 */

        c = HH (c, d, a, b, x[ 5], S33); /* 43 */

        b = HH (b, c, d, a, x[13], S34); /* 44 */

        a = HH (a, b, c, d, x[ 3], S31); /* 45 */

        d = HH (d, a, b, c, x[11], S32); /* 46 */

        c = HH (c, d, a, b, x[ 7], S33); /* 47 */

        b = HH (b, c, d, a, x[15], S34); /* 48 */

        state[0] += a;

        state[1] += b;

        state[2] += c;

        state[3] += d;

    }

}