/**
 * SHA256
 * 
 * An ActionScript 3 implementation of Secure Hash Algorithm, SHA-256, as defined
 * in FIPS PUB 180-2
 * Copyright (c) 2007 Henri Torgemane
 * 
 * Derived from:
 *         A JavaScript implementation of the Secure Hash Standard
 *         Version 0.3 Copyright Angel Marin 2003-2004 - http://anmar.eu.org/
 * Derived from:
 *         A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined
 *         in FIPS PUB 180-1
 *         Version 2.1a Copyright Paul Johnston 2000 - 2002.
 *         Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
 * 
 * See LICENSE.txt for full license information.
 */
package com.hurlant.crypto.hash
{
    

    public class SHA256 extends SHABase implements IHash
    {
        
        protected static const k:Array = [
        0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
        0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
        0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
        0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
        0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
        0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
        0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
        0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2];
        protected var h:Array = [
        0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
        ];
        
        public function SHA256(){
        }
        
        public override function getHashSize():uint
        {
            return 32;
        }
        
        protected override function core(x:Array, len:uint):Array {
            /* append padding */
            x[len >> 5] |= 0x80 << (24 - len % 32);
            x[((len + 64 >> 9) << 4) + 15] = len;
        
            var w:Array = [];
            var a:uint = h[0];
            var b:uint = h[1];
            var c:uint = h[2];
            var d:uint = h[3];
            var e:uint = h[4];
            var f:uint = h[5];
            var g:uint = h[6];
            var h:uint = h[7];
            
            for (var i:uint=0; i<x.length; i+=16) {
                var olda:uint = a;
                var oldb:uint = b;
                var oldc:uint = c;
                var oldd:uint = d;
                var olde:uint = e;
                var oldf:uint = f;
                var oldg:uint = g;
                var oldh:uint = h;

                for (var j:uint=0; j<64; j++) {
                    if (j<16) {
                        w[j] = x[i+j] || 0;
                    } else {
                        var s0:uint = rrol(w[j-15],7)^rrol(w[j-15],18)^(w[j-15]>>>3);
                        var s1:uint = rrol(w[j-2], 17)^rrol(w[j-2],19)^(w[j-2]>>>10);
                        w[j] = w[j-16] + s0 + w[j-7] + s1;
                    }
                    var t2:uint = (rrol(a,2) ^ rrol(a,13) ^ rrol(a,22)) + ((a&b) ^ (a&c) ^ (b&c));
                    var t1:uint = h + (rrol(e,6) ^ rrol(e,11) ^ rrol(e,25)) + ((e&f)^(g&~e)) + k[j] + w[j]
                    h = g;
                    g = f;
                    f = e;
                    e = d + t1;
                    d = c;
                    c = b;
                    b = a;
                    a = t1 + t2;

                }
                a += olda;
                b += oldb;
                c += oldc;
                d += oldd;
                e += olde;
                f += oldf;
                g += oldg;
                h += oldh;
            }
            return [ a,b,c,d,e,f,g,h ];
        }
        
        /*
         * Bitwise rotate a 32-bit number to the right.
         */
        protected function rrol(num:uint, cnt:uint):uint {
          return (num << (32-cnt)) | (num >>> cnt);
        }
        
        public override function toString():String {
            return "sha256";
        }
    }
}