/* Sha512.java -- 
   Copyright (C) 2003, 2006 Free Software Foundation, Inc.

This file is a part of GNU Classpath.

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it under the terms of the GNU General Public License as published by
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USA

Linking this library statically or dynamically with other modules is
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permission to link this library with independent modules to produce an
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package gnu.java.security.hash;

import gnu.java.security.Registry;
import gnu.java.security.util.Util;

/**
 * <p>Implementation of SHA2-3 [SHA-512] per the IETF Draft Specification.</p>
 *
 * <p>References:</p>
 * <ol>
 *    <li><a href="http://ftp.ipv4.heanet.ie/pub/ietf/internet-drafts/draft-ietf-ipsec-ciph-aes-cbc-03.txt">
 *    Descriptions of SHA-256, SHA-384, and SHA-512</a>,</li>
 *    <li>http://csrc.nist.gov/cryptval/shs/sha256-384-512.pdf</li>
 * </ol>
 */
public class Sha512 extends BaseHash
{

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

  private 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 };

  private static final int BLOCK_SIZE = 128; // inner block size in bytes

  private static final String DIGEST0 = "DDAF35A193617ABACC417349AE20413112E6FA4E89A97EA20A9EEEE64B55D39A"
                                        + "2192992A274FC1A836BA3C23A3FEEBBD454D4423643CE80E2A9AC94FA54CA49F";

  private static final long[] w = new long[80];

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

  /** 512-bit interim result. */
  private long h0, h1, h2, h3, h4, h5, h6, h7;

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

  /** Trivial 0-arguments constructor. */
  public Sha512()
  {
    super(Registry.SHA512_HASH, 64, BLOCK_SIZE);
  }

  /**
   * <p>Private constructor for cloning purposes.</p>
   *
   * @param md the instance to clone.
   */
  private Sha512(Sha512 md)
  {
    this();

    this.h0 = md.h0;
    this.h1 = md.h1;
    this.h2 = md.h2;
    this.h3 = md.h3;
    this.h4 = md.h4;
    this.h5 = md.h5;
    this.h6 = md.h6;
    this.h7 = md.h7;
    this.count = md.count;
    this.buffer = (byte[]) md.buffer.clone();
  }

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

  public static final long[] G(long hh0, long hh1, long hh2, long hh3,
                               long hh4, long hh5, long hh6, long hh7,
                               byte[] in, int offset)
  {
    return sha(hh0, hh1, hh2, hh3, hh4, hh5, hh6, hh7, in, offset);
  }

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

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

  public Object clone()
  {
    return new Sha512(this);
  }

  // Implementation of concrete methods in BaseHash --------------------------

  protected void transform(byte[] in, int offset)
  {
    long[] result = sha(h0, h1, h2, h3, h4, h5, h6, h7, in, offset);

    h0 = result[0];
    h1 = result[1];
    h2 = result[2];
    h3 = result[3];
    h4 = result[4];
    h5 = result[5];
    h6 = result[6];
    h7 = result[7];
  }

  protected byte[] padBuffer()
  {
    int n = (int) (count % BLOCK_SIZE);
    int padding = (n < 112) ? (112 - n) : (240 - n);
    byte[] result = new byte[padding + 16];

    // padding is always binary 1 followed by binary 0s
    result[0] = (byte) 0x80;

    // save number of bits, casting the long to an array of 8 bytes
    // TODO: FIX Only ~35 bits of 128 bit counter usable this way
    long bits = count << 3;
    padding += 8;
    result[padding++] = (byte) (bits >>> 56);
    result[padding++] = (byte) (bits >>> 48);
    result[padding++] = (byte) (bits >>> 40);
    result[padding++] = (byte) (bits >>> 32);
    result[padding++] = (byte) (bits >>> 24);
    result[padding++] = (byte) (bits >>> 16);
    result[padding++] = (byte) (bits >>> 8);
    result[padding] = (byte) bits;

    return result;
  }

  protected byte[] getResult()
  {
    return new byte[] { (byte) (h0 >>> 56), (byte) (h0 >>> 48),
                       (byte) (h0 >>> 40), (byte) (h0 >>> 32),
                       (byte) (h0 >>> 24), (byte) (h0 >>> 16),
                       (byte) (h0 >>> 8), (byte) h0, (byte) (h1 >>> 56),
                       (byte) (h1 >>> 48), (byte) (h1 >>> 40),
                       (byte) (h1 >>> 32), (byte) (h1 >>> 24),
                       (byte) (h1 >>> 16), (byte) (h1 >>> 8), (byte) h1,
                       (byte) (h2 >>> 56), (byte) (h2 >>> 48),
                       (byte) (h2 >>> 40), (byte) (h2 >>> 32),
                       (byte) (h2 >>> 24), (byte) (h2 >>> 16),
                       (byte) (h2 >>> 8), (byte) h2, (byte) (h3 >>> 56),
                       (byte) (h3 >>> 48), (byte) (h3 >>> 40),
                       (byte) (h3 >>> 32), (byte) (h3 >>> 24),
                       (byte) (h3 >>> 16), (byte) (h3 >>> 8), (byte) h3,
                       (byte) (h4 >>> 56), (byte) (h4 >>> 48),
                       (byte) (h4 >>> 40), (byte) (h4 >>> 32),
                       (byte) (h4 >>> 24), (byte) (h4 >>> 16),
                       (byte) (h4 >>> 8), (byte) h4, (byte) (h5 >>> 56),
                       (byte) (h5 >>> 48), (byte) (h5 >>> 40),
                       (byte) (h5 >>> 32), (byte) (h5 >>> 24),
                       (byte) (h5 >>> 16), (byte) (h5 >>> 8), (byte) h5,
                       (byte) (h6 >>> 56), (byte) (h6 >>> 48),
                       (byte) (h6 >>> 40), (byte) (h6 >>> 32),
                       (byte) (h6 >>> 24), (byte) (h6 >>> 16),
                       (byte) (h6 >>> 8), (byte) h6, (byte) (h7 >>> 56),
                       (byte) (h7 >>> 48), (byte) (h7 >>> 40),
                       (byte) (h7 >>> 32), (byte) (h7 >>> 24),
                       (byte) (h7 >>> 16), (byte) (h7 >>> 8), (byte) h7 };
  }

  protected void resetContext()
  {
    // magic SHA-512 initialisation constants
    h0 = 0x6a09e667f3bcc908L;
    h1 = 0xbb67ae8584caa73bL;
    h2 = 0x3c6ef372fe94f82bL;
    h3 = 0xa54ff53a5f1d36f1L;
    h4 = 0x510e527fade682d1L;
    h5 = 0x9b05688c2b3e6c1fL;
    h6 = 0x1f83d9abfb41bd6bL;
    h7 = 0x5be0cd19137e2179L;
  }

  public boolean selfTest()
  {
    if (valid == null)
      {
        Sha512 md = new Sha512();
        md.update((byte) 0x61); // a
        md.update((byte) 0x62); // b
        md.update((byte) 0x63); // c
        String result = Util.toString(md.digest());
        valid = Boolean.valueOf(DIGEST0.equals(result));
      }
    return valid.booleanValue();
  }

  // SHA specific methods ----------------------------------------------------

  private static final synchronized long[] sha(long hh0, long hh1, long hh2,
                                               long hh3, long hh4, long hh5,
                                               long hh6, long hh7, byte[] in,
                                               int offset)
  {
    long A = hh0;
    long B = hh1;
    long C = hh2;
    long D = hh3;
    long E = hh4;
    long F = hh5;
    long G = hh6;
    long H = hh7;
    long T, T2;
    int r;

    for (r = 0; r < 16; r++)
      {
        w[r] = (long) in[offset++] << 56 | ((long) in[offset++] & 0xFF) << 48
               | ((long) in[offset++] & 0xFF) << 40
               | ((long) in[offset++] & 0xFF) << 32
               | ((long) in[offset++] & 0xFF) << 24
               | ((long) in[offset++] & 0xFF) << 16
               | ((long) in[offset++] & 0xFF) << 8
               | ((long) in[offset++] & 0xFF);
      }
    for (r = 16; r < 80; r++)
      {
        T = w[r - 2];
        T2 = w[r - 15];
        w[r] = (((T >>> 19) | (T << 45)) ^ ((T >>> 61) | (T << 3)) ^ (T >>> 6))
               + w[r - 7]
               + (((T2 >>> 1) | (T2 << 63)) ^ ((T2 >>> 8) | (T2 << 56)) ^ (T2 >>> 7))
               + w[r - 16];
      }

    for (r = 0; r < 80; r++)
      {
        T = H
            + (((E >>> 14) | (E << 50)) ^ ((E >>> 18) | (E << 46)) ^ ((E >>> 41) | (E << 23)))
            + ((E & F) ^ ((~E) & G)) + k[r] + w[r];
        T2 = (((A >>> 28) | (A << 36)) ^ ((A >>> 34) | (A << 30)) ^ ((A >>> 39) | (A << 25)))
             + ((A & B) ^ (A & C) ^ (B & C));
        H = G;
        G = F;
        F = E;
        E = D + T;
        D = C;
        C = B;
        B = A;
        A = T + T2;
      }

    return new long[] { hh0 + A, hh1 + B, hh2 + C, hh3 + D, hh4 + E, hh5 + F,
                       hh6 + G, hh7 + H };
  }
}
