package org.bouncycastle.crypto.digests;/** * implementation of SHA-1 as outlined in "Handbook of Applied Cryptography", pages 346 - 349. * * It is interesting to ponder why the, apart from the extra IV, the other difference here from MD5 * is the "endienness" of the word processing! */public class SHA1Digest    extends GeneralDigest{    private static final int    DIGEST_LENGTH = 20;    private int     H1, H2, H3, H4, H5;    private int[]   X = new int[80];    private int     xOff;    /**     * Standard constructor     */    public SHA1Digest()    {        reset();    }    /**     * Copy constructor.  This will copy the state of the provided     * message digest.     */    public SHA1Digest(SHA1Digest t)    {        super(t);        H1 = t.H1;        H2 = t.H2;        H3 = t.H3;        H4 = t.H4;        H5 = t.H5;        System.arraycopy(t.X, 0, X, 0, t.X.length);        xOff = t.xOff;    }    public String getAlgorithmName()    {        return "SHA-1";    }    public int getDigestSize()    {        return DIGEST_LENGTH;    }    protected void processWord(        byte[]  in,        int     inOff)    {        X[xOff++] = ((in[inOff] & 0xff) << 24) | ((in[inOff + 1] & 0xff) << 16)                    | ((in[inOff + 2] & 0xff) << 8) | ((in[inOff + 3] & 0xff));         if (xOff == 16)        {            processBlock();        }    }    private void unpackWord(        int     word,        byte[]  out,        int     outOff)    {        out[outOff]     = (byte)(word >>> 24);        out[outOff + 1] = (byte)(word >>> 16);        out[outOff + 2] = (byte)(word >>> 8);        out[outOff + 3] = (byte)word;    }    protected void processLength(        long    bitLength)    {        if (xOff > 14)        {            processBlock();        }        X[14] = (int)(bitLength >>> 32);        X[15] = (int)(bitLength & 0xffffffff);    }    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);        unpackWord(H5, out, outOff + 16);        reset();        return DIGEST_LENGTH;    }    /**     * reset the chaining variables     */    public void reset()    {        super.reset();        H1 = 0x67452301;        H2 = 0xefcdab89;        H3 = 0x98badcfe;        H4 = 0x10325476;        H5 = 0xc3d2e1f0;        xOff = 0;        for (int i = 0; i != X.length; i++)        {            X[i] = 0;        }    }    //    // Additive constants    //    private static final int    Y1 = 0x5a827999;    private static final int    Y2 = 0x6ed9eba1;    private static final int    Y3 = 0x8f1bbcdc;    private static final int    Y4 = 0xca62c1d6;    private int f(        int    u,        int    v,        int    w)    {        return ((u & v) | ((~u) & w));    }    private int h(        int    u,        int    v,        int    w)    {        return (u ^ v ^ w);    }    private int g(        int    u,        int    v,        int    w)    {        return ((u & v) | (u & w) | (v & w));    }    private int rotateLeft(        int    x,        int    n)    {        return (x << n) | (x >>> (32 - n));    }    protected void processBlock()    {        //        // expand 16 word block into 80 word block.        //        for (int i = 16; i <= 79; i++)        {            X[i] = rotateLeft((X[i - 3] ^ X[i - 8] ^ X[i - 14] ^ X[i - 16]), 1);        }        //        // set up working variables.        //        int     A = H1;        int     B = H2;        int     C = H3;        int     D = H4;        int     E = H5;        //        // round 1        //        for (int j = 0; j <= 19; j++)        {            int     t = rotateLeft(A, 5) + f(B, C, D) + E + X[j] + Y1;            E = D;            D = C;            C = rotateLeft(B, 30);            B = A;            A = t;        }        //        // round 2        //        for (int j = 20; j <= 39; j++)        {            int     t = rotateLeft(A, 5) + h(B, C, D) + E + X[j] + Y2;            E = D;            D = C;            C = rotateLeft(B, 30);            B = A;            A = t;        }        //        // round 3        //        for (int j = 40; j <= 59; j++)        {            int     t = rotateLeft(A, 5) + g(B, C, D) + E + X[j] + Y3;            E = D;            D = C;            C = rotateLeft(B, 30);            B = A;            A = t;        }        //        // round 4        //        for (int j = 60; j <= 79; j++)        {            int     t = rotateLeft(A, 5) + h(B, C, D) + E + X[j] + Y4;            E = D;            D = C;            C = rotateLeft(B, 30);            B = A;            A = t;        }        H1 += A;        H2 += B;        H3 += C;        H4 += D;        H5 += E;        //        // reset the offset and clean out the word buffer.        //        xOff = 0;        for (int i = 0; i != X.length; i++)        {            X[i] = 0;        }    }}