SHA256Hashing.js

// Source: https://community.servicenow.com/community?id=community_article&sys_id=97c5faffdb36a3045d782183ca961940
var SHA256Hashing = Class.create();

SHA256Hashing.prototype =

{
	
	initialize: function()
	
	{
		
		var chrsz     = 8;
		
		var hexcase = 0;
		
	},
	
	SHA256:function(s)
	
	{
		
		var chrsz     = 8;
		
		var hexcase = 0;
		
		s = this.Utf8Encode(s);
		
		return this.binb2hex(this.core_sha256(this.str2binb(s), s.length * chrsz));
		
	},
	
	safe_add:function (x, y)
	
	{
		
		var lsw = (x & 0xFFFF) + (y & 0xFFFF);
		
		var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
		
		return (msw << 16) | (lsw & 0xFFFF);
		
	},
	
	S :function(X, n) { return ( X >>> n ) | (X << (32 - n)); },
		
	R :function(X, n) { return ( X >>> n ); },
			
	Ch:function(x, y, z) { return ((x & y) ^ ((~x) & z)); },
				
	Maj:function(x, y, z) { return ((x & y) ^ (x & z) ^ (y & z)); },
					
	Sigma0256:function(x) { return (this.S(x, 2) ^ this.S(x, 13) ^ this.S(x, 22)); },
						
	Sigma1256:function(x) { return (this.S(x, 6) ^ this.S(x, 11) ^ this.S(x, 25)); },
							
	Gamma0256:function(x) { return (this.S(x, 7) ^ this.S(x, 18) ^ this.R(x, 3)); },
								
	Gamma1256:function(x) { return (this.S(x, 17) ^ this.S(x, 19) ^ this.R(x, 10)); },
	
	core_sha256 :function(m, l) {
		
		var K = new Array(0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5, 0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5, 0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3, 0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174, 0xE49B69C1, 0xEFBE4786, 0xFC19DC6, 0x240CA1CC, 0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA, 0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7, 0xC6E00BF3, 0xD5A79147, 0x6CA6351, 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);
		
		var HASH = new Array(0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A, 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19);
		
		var W = new Array(64);
		
		var a, b, c, d, e, f, g, h, i, j;
		
		var T1, T2;
		
		m[l >> 5] |= 0x80 << (24 - l % 32);
		
		m[((l + 64 >> 9) << 4) + 15] = l;
		
		for ( var i = 0; i<m.length; i+=16 )
			
		{
			
			a = HASH[0];
			
			b = HASH[1];
			
			c = HASH[2];
			
			d = HASH[3];
			
			e = HASH[4];
			
			f = HASH[5];
			
			g = HASH[6];
			
			h = HASH[7];
			
			for ( var j = 0; j<64; j++)
				
			{
				
				if (j < 16) W[j] = m[j + i];
					
				else W[j] = this.safe_add(this.safe_add(this.safe_add(this.Gamma1256(W[j - 2]), W[j - 7]), this.Gamma0256(W[j - 15])), W[j - 16]);
					
				T1 = this.safe_add(this.safe_add(this.safe_add(this.safe_add(h, this.Sigma1256(e)), this.Ch(e, f, g)), K[j]), W[j]);
				
				T2 = this.safe_add(this.Sigma0256(a), this.Maj(a, b, c));
				
				h = g;
				
				g = f;
				
				f = e;
				
				e = this.safe_add(d, T1);
				
				d = c;
				
				c = b;
				
				b = a;
				
				a = this.safe_add(T1, T2);
				
			}
			
			HASH[0] = this.safe_add(a, HASH[0]);
			
			HASH[1] = this.safe_add(b, HASH[1]);
			
			HASH[2] = this.safe_add(c, HASH[2]);
			
			HASH[3] = this.safe_add(d, HASH[3]);
			
			HASH[4] = this.safe_add(e, HASH[4]);
			
			HASH[5] = this.safe_add(f, HASH[5]);
			
			HASH[6] = this.safe_add(g, HASH[6]);
			
			HASH[7] = this.safe_add(h, HASH[7]);
			
		}
		
		return HASH;
		
	},
	
	str2binb :function(str)
	
	{
		
		var chrsz     = 8;
		
		var bin = Array();
		
		var mask = (1 << chrsz) - 1;
		
		for(var i = 0; i < str.length * chrsz; i += chrsz)
			
		{
			
			bin[i>>5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - i%32);
			
		}
		
		return bin;
		
	},
	
	Utf8Encode:function(string)
	
	{
		
		string = string.replace(/\r\n/g,"\n");
		
		var utftext = "";
		
		for (var n = 0; n < string.length; n++) {
			
			var c = string.charCodeAt(n);
			
			if (c < 128)
				
			{
				
				utftext += String.fromCharCode(c);
				
			}
			
			else if((c > 127) && (c < 2048)) {
				
				utftext += String.fromCharCode((c >> 6) | 192);
				
				utftext += String.fromCharCode((c & 63) | 128);
				
			}
			
			else {
				
				utftext += String.fromCharCode((c >> 12) | 224);
				
				utftext += String.fromCharCode(((c >> 6) & 63) | 128);
				
				utftext += String.fromCharCode((c & 63) | 128);
				
			}
			
		}
		
		return utftext;
		
	},
	
	binb2hex :function(binarray)
	
	{
		
		var hexcase = 0;
		
		var hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";
		
		var str = "";
		
		for(var i = 0; i < binarray.length * 4; i++) {
			
			str += hex_tab.charAt((binarray[i>>2] >> ((3 - i%4)*8+4)) & 0xF) +
			
			hex_tab.charAt((binarray[i>>2] >> ((3 - i%4)*8   )) & 0xF);
			
		}
		
		return str;
		
	}
	
};