/*
  Copyright (c) 2008, Adobe Systems Incorporated
  All rights reserved.

  Redistribution and use in source and binary forms, with or without 
  modification, are permitted provided that the following conditions are
  met:

  * Redistributions of source code must retain the above copyright notice, 
    this list of conditions and the following disclaimer.
  
  * Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the 
    documentation and/or other materials provided with the distribution.
  
  * Neither the name of Adobe Systems Incorporated nor the names of its 
    contributors may be used to endorse or promote products derived from 
    this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

package classes.adobe.crypto {
	
	import classes.adobe.utils.IntUtil;
	import flash.utils.ByteArray;	
	/**
	 * The MD5 Message-Digest Algorithm
	 *
	 * Implementation based on algorithm description at 
	 * http://www.faqs.org/rfcs/rfc1321.html
	 */
	public class MD5 {
		
		/**
		 * Performs the MD5 hash algorithm on a string.
		 *
		 * @param s The string to hash
		 * @return A string containing the hash value of s
		 * @langversion ActionScript 3.0
		 * @playerversion Flash 8.5
		 * @tiptext
		 */
		 
		public static function hash(s:String) :String{
			//Convert to byteArray and send through hashBinary function
			// so as to only have complex code in one location
			var ba:ByteArray = new ByteArray();
			ba.writeUTFBytes(s);	
			return hashBinary(ba);
		}
		/**
		 * Performs the MD5 hash algorithm on a ByteArray.
		 *
		 * @param s The string to hash
		 * @return A string containing the hash value of s
		 * @langversion ActionScript 3.0
		 * @playerversion Flash 8.5
		 * @tiptext
		 */	 
		public static function hashBinary( s:ByteArray ):String {
			// initialize the md buffers
			var a:int = 1732584193;
			var b:int = -271733879;
			var c:int = -1732584194;
			var d:int = 271733878;
			
			// variables to store previous values
			var aa:int;
			var bb:int;
			var cc:int;
			var dd:int;
			
			// create the blocks from the string and
			// save the length as a local var to reduce
			// lookup in the loop below
			var x:Array = createBlocks( s );
			var len:int = x.length;
			
			// loop over all of the blocks
			for ( var i:int = 0; i < len; i += 16) {
				// save previous values
				aa = a;
				bb = b;
				cc = c;
				dd = d;				
				
				// Round 1
				a = ff( a, b, c, d, x[int(i+ 0)],  7, -680876936 ); 	// 1
				d = ff( d, a, b, c, x[int(i+ 1)], 12, -389564586 );	// 2
				c = ff( c, d, a, b, x[int(i+ 2)], 17, 606105819 ); 	// 3
				b = ff( b, c, d, a, x[int(i+ 3)], 22, -1044525330 );	// 4
				a = ff( a, b, c, d, x[int(i+ 4)],  7, -176418897 ); 	// 5
				d = ff( d, a, b, c, x[int(i+ 5)], 12, 1200080426 ); 	// 6
				c = ff( c, d, a, b, x[int(i+ 6)], 17, -1473231341 );	// 7
				b = ff( b, c, d, a, x[int(i+ 7)], 22, -45705983 ); 	// 8
				a = ff( a, b, c, d, x[int(i+ 8)],  7, 1770035416 ); 	// 9
				d = ff( d, a, b, c, x[int(i+ 9)], 12, -1958414417 );	// 10
				c = ff( c, d, a, b, x[int(i+10)], 17, -42063 ); 		// 11
				b = ff( b, c, d, a, x[int(i+11)], 22, -1990404162 );	// 12
				a = ff( a, b, c, d, x[int(i+12)],  7, 1804603682 ); 	// 13
				d = ff( d, a, b, c, x[int(i+13)], 12, -40341101 ); 	// 14
				c = ff( c, d, a, b, x[int(i+14)], 17, -1502002290 );	// 15
				b = ff( b, c, d, a, x[int(i+15)], 22, 1236535329 ); 	// 16
				
				// Round 2
				a = gg( a, b, c, d, x[int(i+ 1)],  5, -165796510 ); 	// 17
				d = gg( d, a, b, c, x[int(i+ 6)],  9, -1069501632 );	// 18
				c = gg( c, d, a, b, x[int(i+11)], 14, 643717713 ); 	// 19
				b = gg( b, c, d, a, x[int(i+ 0)], 20, -373897302 ); 	// 20
				a = gg( a, b, c, d, x[int(i+ 5)],  5, -701558691 ); 	// 21
				d = gg( d, a, b, c, x[int(i+10)],  9, 38016083 ); 	// 22
				c = gg( c, d, a, b, x[int(i+15)], 14, -660478335 ); 	// 23
				b = gg( b, c, d, a, x[int(i+ 4)], 20, -405537848 ); 	// 24
				a = gg( a, b, c, d, x[int(i+ 9)],  5, 568446438 ); 	// 25
				d = gg( d, a, b, c, x[int(i+14)],  9, -1019803690 );	// 26
				c = gg( c, d, a, b, x[int(i+ 3)], 14, -187363961 ); 	// 27
				b = gg( b, c, d, a, x[int(i+ 8)], 20, 1163531501 ); 	// 28
				a = gg( a, b, c, d, x[int(i+13)],  5, -1444681467 );	// 29
				d = gg( d, a, b, c, x[int(i+ 2)],  9, -51403784 ); 	// 30
				c = gg( c, d, a, b, x[int(i+ 7)], 14, 1735328473 ); 	// 31
				b = gg( b, c, d, a, x[int(i+12)], 20, -1926607734 );	// 32
				
				// Round 3
				a = hh( a, b, c, d, x[int(i+ 5)],  4, -378558 ); 	// 33
				d = hh( d, a, b, c, x[int(i+ 8)], 11, -2022574463 );	// 34
				c = hh( c, d, a, b, x[int(i+11)], 16, 1839030562 ); 	// 35
				b = hh( b, c, d, a, x[int(i+14)], 23, -35309556 ); 	// 36
				a = hh( a, b, c, d, x[int(i+ 1)],  4, -1530992060 );	// 37
				d = hh( d, a, b, c, x[int(i+ 4)], 11, 1272893353 ); 	// 38
				c = hh( c, d, a, b, x[int(i+ 7)], 16, -155497632 ); 	// 39
				b = hh( b, c, d, a, x[int(i+10)], 23, -1094730640 );	// 40
				a = hh( a, b, c, d, x[int(i+13)],  4, 681279174 ); 	// 41
				d = hh( d, a, b, c, x[int(i+ 0)], 11, -358537222 ); 	// 42
				c = hh( c, d, a, b, x[int(i+ 3)], 16, -722521979 ); 	// 43
				b = hh( b, c, d, a, x[int(i+ 6)], 23, 76029189 ); 	// 44
				a = hh( a, b, c, d, x[int(i+ 9)],  4, -640364487 ); 	// 45
				d = hh( d, a, b, c, x[int(i+12)], 11, -421815835 ); 	// 46
				c = hh( c, d, a, b, x[int(i+15)], 16, 530742520 ); 	// 47
				b = hh( b, c, d, a, x[int(i+ 2)], 23, -995338651 ); 	// 48
				
				// Round 4
				a = ii( a, b, c, d, x[int(i+ 0)],  6, -198630844 ); 	// 49
				d = ii( d, a, b, c, x[int(i+ 7)], 10, 1126891415 ); 	// 50
				c = ii( c, d, a, b, x[int(i+14)], 15, -1416354905 );	// 51
				b = ii( b, c, d, a, x[int(i+ 5)], 21, -57434055 ); 	// 52
				a = ii( a, b, c, d, x[int(i+12)],  6, 1700485571 ); 	// 53
				d = ii( d, a, b, c, x[int(i+ 3)], 10, -1894986606 );	// 54
				c = ii( c, d, a, b, x[int(i+10)], 15, -1051523 ); 	// 55
				b = ii( b, c, d, a, x[int(i+ 1)], 21, -2054922799 );	// 56
				a = ii( a, b, c, d, x[int(i+ 8)],  6, 1873313359 ); 	// 57
				d = ii( d, a, b, c, x[int(i+15)], 10, -30611744 ); 	// 58
				c = ii( c, d, a, b, x[int(i+ 6)], 15, -1560198380 );	// 59
				b = ii( b, c, d, a, x[int(i+13)], 21, 1309151649 ); 	// 60
				a = ii( a, b, c, d, x[int(i+ 4)],  6, -145523070 ); 	// 61
				d = ii( d, a, b, c, x[int(i+11)], 10, -1120210379 );	// 62
				c = ii( c, d, a, b, x[int(i+ 2)], 15, 718787259 ); 	// 63
				b = ii( b, c, d, a, x[int(i+ 9)], 21, -343485551 ); 	// 64

				a += aa;
				b += bb;
				c += cc;
				d += dd;
			}

			// Finish up by concatening the buffers with their hex output
			return IntUtil.toHex( a ) + IntUtil.toHex( b ) + IntUtil.toHex( c ) + IntUtil.toHex( d );
		}
		
		/**
		 * Auxiliary function f as defined in RFC
		 */
		private static function f( x:int, y:int, z:int ):int {
			return ( x & y ) | ( (~x) & z );
		}
		
		/**
		 * Auxiliary function g as defined in RFC
		 */
		private static function g( x:int, y:int, z:int ):int {
			return ( x & z ) | ( y & (~z) );
		}
		
		/**
		 * Auxiliary function h as defined in RFC
		 */
		private static function h( x:int, y:int, z:int ):int {
			return x ^ y ^ z;
		}
		
		/**
		 * Auxiliary function i as defined in RFC
		 */
		private static function i( x:int, y:int, z:int ):int {
			return y ^ ( x | (~z) );
		}
		
		/**
		 * A generic transformation function.  The logic of ff, gg, hh, and
		 * ii are all the same, minus the function used, so pull that logic
		 * out and simplify the method bodies for the transoformation functions.
		 */
		private static function transform( func:Function, a:int, b:int, c:int, d:int, x:int, s:int, t:int):int {
			var tmp:int = a + int( func( b, c, d ) ) + x + t;
			return IntUtil.rol( tmp, s ) +  b;
		}
		
		/**
		 * ff transformation function
		 */
		private static function ff ( a:int, b:int, c:int, d:int, x:int, s:int, t:int ):int {
			return transform( f, a, b, c, d, x, s, t );
		}
		
		/**
		 * gg transformation function
		 */
		private static function gg ( a:int, b:int, c:int, d:int, x:int, s:int, t:int ):int {
			return transform( g, a, b, c, d, x, s, t );
		}
		
		/**
		 * hh transformation function
		 */
		private static function hh ( a:int, b:int, c:int, d:int, x:int, s:int, t:int ):int {
			return transform( h, a, b, c, d, x, s, t );
		}
		
		/**
		 * ii transformation function
		 */
		private static function ii ( a:int, b:int, c:int, d:int, x:int, s:int, t:int ):int {
			return transform( i, a, b, c, d, x, s, t );
		}
		
		/**
		 * Converts a string to a sequence of 16-word blocks
		 * that we'll do the processing on.  Appends padding
		 * and length in the process.
		 *
		 * @param s The string to split into blocks
		 * @return An array containing the blocks that s was
		 *			split into.
		 */
		private static function createBlocks( s:ByteArray ):Array {
			var blocks:Array = new Array();
			var len:int = s.length * 8;
			var mask:int = 0xFF; // ignore hi byte of characters > 0xFF
			for( var i:int = 0; i < len; i += 8 ) {
				blocks[ int(i >> 5) ] |= ( s[ i / 8 ] & mask ) << ( i % 32 );
			}
			
			// append padding and length
			blocks[ int(len >> 5) ] |= 0x80 << ( len % 32 );
			blocks[ int(( ( ( len + 64 ) >>> 9 ) << 4 ) + 14) ] = len;
			return blocks;
		}
		
	}
}
