source: Dev/trunk/src/client/dojox/encoding/digests/SHA256.js

define(["./_sha-32"], function(sha32){
        //      The 256-bit implementation of SHA-2
        var hash = [
                0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
                0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
        ];

        var SHA256 = function(/* String */data, /* sha32.outputTypes? */outputType){
                var out = outputType || sha32.outputTypes.Base64;
                data = sha32.stringToUtf8(data);
                var wa = sha32.digest(sha32.toWord(data), data.length * 8, hash, 256);
                switch(out){
                        case sha32.outputTypes.Raw: {
                                return wa;
                        }
                        case sha32.outputTypes.Hex: {
                                return sha32.toHex(wa);
                        }
                        case sha32.outputTypes.String: {
                                return sha32._toString(wa);
                        }
                        default: {
                                return sha32.toBase64(wa);
                        }
                }
        };

        SHA256._hmac = function(/* String */data, /* String */key, /* sha32.outputTypes? */outputType){
                var out = outputType || sha32.outputTypes.Base64;
                data = sha32.stringToUtf8(data);
                key = sha32.stringToUtf8(key);

                //      prepare the key
                var wa = sha32.toWord(key);
                if(wa.length > 16){
                        wa = sha32.digest(wa, key.length * 8, hash, 256);
                }

                //      set up the pads
                var ipad = new Array(16), opad = new Array(16);
                for(var i=0; i<16; i++){
                        ipad[i] = wa[i] ^ 0x36363636;
                        opad[i] = wa[i] ^ 0x5c5c5c5c;
                }

                //      make the final digest
                var r1 = sha32.digest(ipad.concat(sha32.toWord(data)), 512 + data.length * 8, hash, 256);
                var r2 = sha32.digest(opad.concat(r1), 512 + 160, hash, 256);

                //      return the output.
                switch(out){
                        case sha32.outputTypes.Raw: {
                                return wa;
                        }
                        case sha32.outputTypes.Hex: {
                                return sha32.toHex(wa);
                        }
                        case sha32.outputTypes.String: {
                                return sha32._toString(wa);
                        }
                        default: {
                                return sha32.toBase64(wa);
                        }
                }
        };

        return SHA256;
});