package gnu.crypto.hash;

// ----------------------------------------------------------------------------
// $Id: Sha512.java,v 1.2 2005/10/06 04:24:14 rsdio Exp $
//
// Copyright (C) 2003 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
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// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING.  If not, write to the
//
//    Free Software Foundation Inc.,
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//    USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
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// you permission to link this library with independent modules to
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// independent modules, and to copy and distribute the resulting
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// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------

import gnu.crypto.Registry;
import gnu.crypto.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>
 *
 * @version $Revision: 1.2 $
 */
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 = new Boolean(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
      };
   }
}
