package org.bouncycastle.crypto.digests;

import org.bouncycastle.crypto.ExtendedDigest;
import org.bouncycastle.crypto.util.Pack;

/**
 * Base class for SHA-384 and SHA-512.
 */
public abstract class LongDigest
    implements ExtendedDigest
{
    private static final int BYTE_LENGTH = 128;
    
    private byte[]  xBuf;
    private int     xBufOff;

    private long    byteCount1;
    private long    byteCount2;

    protected long    H1, H2, H3, H4, H5, H6, H7, H8;

    private long[]  W = new long[80];
    private int     wOff;

    /**
     * Constructor for variable length word
     */
    protected LongDigest()
    {
        xBuf = new byte[8];
        xBufOff = 0;

        reset();
    }

    /**
     * Copy constructor.  We are using copy constructors in place
     * of the Object.clone() interface as this interface is not
     * supported by J2ME.
     */
    protected LongDigest(LongDigest t)
    {
        xBuf = new byte[t.xBuf.length];
        System.arraycopy(t.xBuf, 0, xBuf, 0, t.xBuf.length);

        xBufOff = t.xBufOff;
        byteCount1 = t.byteCount1;
        byteCount2 = t.byteCount2;

        H1 = t.H1;
        H2 = t.H2;
        H3 = t.H3;
        H4 = t.H4;
        H5 = t.H5;
        H6 = t.H6;
        H7 = t.H7;
        H8 = t.H8;

        System.arraycopy(t.W, 0, W, 0, t.W.length);
        wOff = t.wOff;
    }

    public void update(
        byte in)
    {
        xBuf[xBufOff++] = in;

        if (xBufOff == xBuf.length)
        {
            processWord(xBuf, 0);
            xBufOff = 0;
        }

        byteCount1++;
    }

    public void update(
        byte[]  in,
        int     inOff,
        int     len)
    {
        //
        // fill the current word
        //
        while ((xBufOff != 0) && (len > 0))
        {
            update(in[inOff]);

            inOff++;
            len--;
        }

        //
        // process whole words.
        //
        while (len > xBuf.length)
        {
            processWord(in, inOff);

            inOff += xBuf.length;
            len -= xBuf.length;
            byteCount1 += xBuf.length;
        }

        //
        // load in the remainder.
        //
        while (len > 0)
        {
            update(in[inOff]);

            inOff++;
            len--;
        }
    }

    public void finish()
    {
        adjustByteCounts();

        long    lowBitLength = byteCount1 << 3;
        long    hiBitLength = byteCount2;

        //
        // add the pad bytes.
        //
        update((byte)128);

        while (xBufOff != 0)
        {
            update((byte)0);
        }

        processLength(lowBitLength, hiBitLength);

        processBlock();
    }

    public void reset()
    {
        byteCount1 = 0;
        byteCount2 = 0;

        xBufOff = 0;
        for (int i = 0; i < xBuf.length; i++)
        {
            xBuf[i] = 0;
        }

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

    public int getByteLength()
    {
        return BYTE_LENGTH;
    }
    
    protected void processWord(
        byte[]  in,
        int     inOff)
    {
        W[wOff] = Pack.bigEndianToLong(in, inOff);

        if (++wOff == 16)
        {
            processBlock();
        }
    }

    /**
     * adjust the byte counts so that byteCount2 represents the
     * upper long (less 3 bits) word of the byte count.
     */
    private void adjustByteCounts()
    {
        if (byteCount1 > 0x1fffffffffffffffL)
        {
            byteCount2 += (byteCount1 >>> 61);
            byteCount1 &= 0x1fffffffffffffffL;
        }
    }

    protected void processLength(
        long    lowW,
        long    hiW)
    {
        if (wOff > 14)
        {
            processBlock();
        }

        W[14] = hiW;
        W[15] = lowW;
    }

    protected void processBlock()
    {
        adjustByteCounts();

        //
        // expand 16 word block into 80 word blocks.
        //
        for (int t = 16; t <= 79; t++)
        {
            W[t] = Sigma1(W[t - 2]) + W[t - 7] + Sigma0(W[t - 15]) + W[t - 16];
        }

        //
        // set up working variables.
        //
        long     a = H1;
        long     b = H2;
        long     c = H3;
        long     d = H4;
        long     e = H5;
        long     f = H6;
        long     g = H7;
        long     h = H8;

        int t = 0;     
        for(int i = 0; i < 10; i ++)
        {
          // t = 8 * i
          h += Sum1(e) + Ch(e, f, g) + K[t] + W[t++];
          d += h;
          h += Sum0(a) + Maj(a, b, c);

          // t = 8 * i + 1
          g += Sum1(d) + Ch(d, e, f) + K[t] + W[t++];
          c += g;
          g += Sum0(h) + Maj(h, a, b);

          // t = 8 * i + 2
          f += Sum1(c) + Ch(c, d, e) + K[t] + W[t++];
          b += f;
          f += Sum0(g) + Maj(g, h, a);

          // t = 8 * i + 3
          e += Sum1(b) + Ch(b, c, d) + K[t] + W[t++];
          a += e;
          e += Sum0(f) + Maj(f, g, h);

          // t = 8 * i + 4
          d += Sum1(a) + Ch(a, b, c) + K[t] + W[t++];
          h += d;
          d += Sum0(e) + Maj(e, f, g);

          // t = 8 * i + 5
          c += Sum1(h) + Ch(h, a, b) + K[t] + W[t++];
          g += c;
          c += Sum0(d) + Maj(d, e, f);

          // t = 8 * i + 6
          b += Sum1(g) + Ch(g, h, a) + K[t] + W[t++];
          f += b;
          b += Sum0(c) + Maj(c, d, e);

          // t = 8 * i + 7
          a += Sum1(f) + Ch(f, g, h) + K[t] + W[t++];
          e += a;
          a += Sum0(b) + Maj(b, c, d);
        }
 
        H1 += a;
        H2 += b;
        H3 += c;
        H4 += d;
        H5 += e;
        H6 += f;
        H7 += g;
        H8 += h;

        //
        // reset the offset and clean out the word buffer.
        //
        wOff = 0;
        for (int i = 0; i < 16; i++)
        {
            W[i] = 0;
        }
    }

    /* SHA-384 and SHA-512 functions (as for SHA-256 but for longs) */
    private long Ch(
        long    x,
        long    y,
        long    z)
    {
        return ((x & y) ^ ((~x) & z));
    }

    private long Maj(
        long    x,
        long    y,
        long    z)
    {
        return ((x & y) ^ (x & z) ^ (y & z));
    }

    private long Sum0(
        long    x)
    {
        return ((x << 36)|(x >>> 28)) ^ ((x << 30)|(x >>> 34)) ^ ((x << 25)|(x >>> 39));
    }

    private long Sum1(
        long    x)
    {
        return ((x << 50)|(x >>> 14)) ^ ((x << 46)|(x >>> 18)) ^ ((x << 23)|(x >>> 41));
    }

    private long Sigma0(
        long    x)
    {
        return ((x << 63)|(x >>> 1)) ^ ((x << 56)|(x >>> 8)) ^ (x >>> 7);
    }

    private long Sigma1(
        long    x)
    {
        return ((x << 45)|(x >>> 19)) ^ ((x << 3)|(x >>> 61)) ^ (x >>> 6);
    }

    /* SHA-384 and SHA-512 Constants
     * (represent the first 64 bits of the fractional parts of the
     * cube roots of the first sixty-four prime numbers)
     */
    static final long K[] = {
0x428a2f98d728ae22L, 0x7137449123ef65cdL, 0xb5c0fbcfec4d3b2fL, 0xe9b5dba58189dbbcL,
0x3956c25bf348b538L, 0x59f111f1b605d019L, 0x923f82a4af194f9bL, 0xab1c5ed5da6d8118L,
0xd807aa98a3030242L, 0x12835b0145706fbeL, 0x243185be4ee4b28cL, 0x550c7dc3d5ffb4e2L,
0x72be5d74f27b896fL, 0x80deb1fe3b1696b1L, 0x9bdc06a725c71235L, 0xc19bf174cf692694L,
0xe49b69c19ef14ad2L, 0xefbe4786384f25e3L, 0x0fc19dc68b8cd5b5L, 0x240ca1cc77ac9c65L,
0x2de92c6f592b0275L, 0x4a7484aa6ea6e483L, 0x5cb0a9dcbd41fbd4L, 0x76f988da831153b5L,
0x983e5152ee66dfabL, 0xa831c66d2db43210L, 0xb00327c898fb213fL, 0xbf597fc7beef0ee4L,
0xc6e00bf33da88fc2L, 0xd5a79147930aa725L, 0x06ca6351e003826fL, 0x142929670a0e6e70L,
0x27b70a8546d22ffcL, 0x2e1b21385c26c926L, 0x4d2c6dfc5ac42aedL, 0x53380d139d95b3dfL,
0x650a73548baf63deL, 0x766a0abb3c77b2a8L, 0x81c2c92e47edaee6L, 0x92722c851482353bL,
0xa2bfe8a14cf10364L, 0xa81a664bbc423001L, 0xc24b8b70d0f89791L, 0xc76c51a30654be30L,
0xd192e819d6ef5218L, 0xd69906245565a910L, 0xf40e35855771202aL, 0x106aa07032bbd1b8L,
0x19a4c116b8d2d0c8L, 0x1e376c085141ab53L, 0x2748774cdf8eeb99L, 0x34b0bcb5e19b48a8L,
0x391c0cb3c5c95a63L, 0x4ed8aa4ae3418acbL, 0x5b9cca4f7763e373L, 0x682e6ff3d6b2b8a3L,
0x748f82ee5defb2fcL, 0x78a5636f43172f60L, 0x84c87814a1f0ab72L, 0x8cc702081a6439ecL,
0x90befffa23631e28L, 0xa4506cebde82bde9L, 0xbef9a3f7b2c67915L, 0xc67178f2e372532bL,
0xca273eceea26619cL, 0xd186b8c721c0c207L, 0xeada7dd6cde0eb1eL, 0xf57d4f7fee6ed178L,
0x06f067aa72176fbaL, 0x0a637dc5a2c898a6L, 0x113f9804bef90daeL, 0x1b710b35131c471bL,
0x28db77f523047d84L, 0x32caab7b40c72493L, 0x3c9ebe0a15c9bebcL, 0x431d67c49c100d4cL,
0x4cc5d4becb3e42b6L, 0x597f299cfc657e2aL, 0x5fcb6fab3ad6faecL, 0x6c44198c4a475817L
    };
}