JS MD5加密(16/32位)

String.prototype.MD5 = function (bit) {
            var sMessage = this;
            function RotateLeft(lValue, iShiftBits) { return (lValue << iShiftBits) | (lValue >>> (32 - iShiftBits)); }
            function AddUnsigned(lX, lY) {
                var lX4, lY4, lX8, lY8, lResult;
                lX8 = (lX & 0x80000000);
                lY8 = (lY & 0x80000000);
                lX4 = (lX & 0x40000000);
                lY4 = (lY & 0x40000000);
                lResult = (lX & 0x3FFFFFFF) + (lY & 0x3FFFFFFF);
                if (lX4 & lY4) return (lResult ^ 0x80000000 ^ lX8 ^ lY8);
                if (lX4 | lY4) {
                    if (lResult & 0x40000000) return (lResult ^ 0xC0000000 ^ lX8 ^ lY8);
                    else return (lResult ^ 0x40000000 ^ lX8 ^ lY8);
                } else return (lResult ^ lX8 ^ lY8);
            }
            function F(x, y, z) { return (x & y) | ((~x) & z); }
            function G(x, y, z) { return (x & z) | (y & (~z)); }
            function H(x, y, z) { return (x ^ y ^ z); }
            function I(x, y, z) { return (y ^ (x | (~z))); }
            function FF(a, b, c, d, x, s, ac) {
                a = AddUnsigned(a, AddUnsigned(AddUnsigned(F(b, c, d), x), ac));
                return AddUnsigned(RotateLeft(a, s), b);
            }
            function GG(a, b, c, d, x, s, ac) {
                a = AddUnsigned(a, AddUnsigned(AddUnsigned(G(b, c, d), x), ac));
                return AddUnsigned(RotateLeft(a, s), b);
            }
            function HH(a, b, c, d, x, s, ac) {
                a = AddUnsigned(a, AddUnsigned(AddUnsigned(H(b, c, d), x), ac));
                return AddUnsigned(RotateLeft(a, s), b);
            }
            function II(a, b, c, d, x, s, ac) {
                a = AddUnsigned(a, AddUnsigned(AddUnsigned(I(b, c, d), x), ac));
                return AddUnsigned(RotateLeft(a, s), b);
            }
            function ConvertToWordArray(sMessage) {
                var lWordCount;
                var lMessageLength = sMessage.length;
                var lNumberOfWords_temp1 = lMessageLength + 8;
                var lNumberOfWords_temp2 = (lNumberOfWords_temp1 - (lNumberOfWords_temp1 % 64)) / 64;
                var lNumberOfWords = (lNumberOfWords_temp2 + 1) * 16;
                var lWordArray = Array(lNumberOfWords - 1);
                var lBytePosition = 0;
                var lByteCount = 0;
                while (lByteCount < lMessageLength) {
                    lWordCount = (lByteCount - (lByteCount % 4)) / 4;
                    lBytePosition = (lByteCount % 4) * 8;
                    lWordArray[lWordCount] = (lWordArray[lWordCount] | (sMessage.charCodeAt(lByteCount) << lBytePosition));
                    lByteCount++;
                }
                lWordCount = (lByteCount - (lByteCount % 4)) / 4;
                lBytePosition = (lByteCount % 4) * 8;
                lWordArray[lWordCount] = lWordArray[lWordCount] | (0x80 << lBytePosition);
                lWordArray[lNumberOfWords - 2] = lMessageLength << 3;
                lWordArray[lNumberOfWords - 1] = lMessageLength >>> 29;
                return lWordArray;
            }
            function WordToHex(lValue) {
                var WordToHexValue = "", WordToHexValue_temp = "", lByte, lCount;
                for (lCount = 0; lCount <= 3; lCount++) {
                    lByte = (lValue >>> (lCount * 8)) & 255;
                    WordToHexValue_temp = "0" + lByte.toString(16);
                    WordToHexValue = WordToHexValue + WordToHexValue_temp.substr(WordToHexValue_temp.length - 2, 2);
                }
                return WordToHexValue;
            }
            var x = Array();
            var k, AA, BB, CC, DD, a, b, c, d
            var S11 = 7, S12 = 12, S13 = 17, S14 = 22;
            var S21 = 5, S22 = 9, S23 = 14, S24 = 20;
            var S31 = 4, S32 = 11, S33 = 16, S34 = 23;
            var S41 = 6, S42 = 10, S43 = 15, S44 = 21;
            // Steps 1 and 2. Append padding bits and length and convert to words 
            x = ConvertToWordArray(sMessage);
            // Step 3. Initialise 
            a = 0x67452301; b = 0xEFCDAB89; c = 0x98BADCFE; d = 0x10325476;
            // Step 4. Process the message in 16-word blocks 
            for (k = 0; k < x.length; k += 16) {
                AA = a; BB = b; CC = c; DD = d;
                a = FF(a, b, c, d, x[k + 0], S11, 0xD76AA478);
                d = FF(d, a, b, c, x[k + 1], S12, 0xE8C7B756);
                c = FF(c, d, a, b, x[k + 2], S13, 0x242070DB);
                b = FF(b, c, d, a, x[k + 3], S14, 0xC1BDCEEE);
                a = FF(a, b, c, d, x[k + 4], S11, 0xF57C0FAF);
                d = FF(d, a, b, c, x[k + 5], S12, 0x4787C62A);
                c = FF(c, d, a, b, x[k + 6], S13, 0xA8304613);
                b = FF(b, c, d, a, x[k + 7], S14, 0xFD469501);
                a = FF(a, b, c, d, x[k + 8], S11, 0x698098D8);
                d = FF(d, a, b, c, x[k + 9], S12, 0x8B44F7AF);
                c = FF(c, d, a, b, x[k + 10], S13, 0xFFFF5BB1);
                b = FF(b, c, d, a, x[k + 11], S14, 0x895CD7BE);
                a = FF(a, b, c, d, x[k + 12], S11, 0x6B901122);
                d = FF(d, a, b, c, x[k + 13], S12, 0xFD987193);
                c = FF(c, d, a, b, x[k + 14], S13, 0xA679438E);
                b = FF(b, c, d, a, x[k + 15], S14, 0x49B40821);
                a = GG(a, b, c, d, x[k + 1], S21, 0xF61E2562);
                d = GG(d, a, b, c, x[k + 6], S22, 0xC040B340);
                c = GG(c, d, a, b, x[k + 11], S23, 0x265E5A51);
                b = GG(b, c, d, a, x[k + 0], S24, 0xE9B6C7AA);
                a = GG(a, b, c, d, x[k + 5], S21, 0xD62F105D);
                d = GG(d, a, b, c, x[k + 10], S22, 0x2441453);
                c = GG(c, d, a, b, x[k + 15], S23, 0xD8A1E681);
                b = GG(b, c, d, a, x[k + 4], S24, 0xE7D3FBC8);
                a = GG(a, b, c, d, x[k + 9], S21, 0x21E1CDE6);
                d = GG(d, a, b, c, x[k + 14], S22, 0xC33707D6);
                c = GG(c, d, a, b, x[k + 3], S23, 0xF4D50D87);
                b = GG(b, c, d, a, x[k + 8], S24, 0x455A14ED);
                a = GG(a, b, c, d, x[k + 13], S21, 0xA9E3E905);
                d = GG(d, a, b, c, x[k + 2], S22, 0xFCEFA3F8);
                c = GG(c, d, a, b, x[k + 7], S23, 0x676F02D9);
                b = GG(b, c, d, a, x[k + 12], S24, 0x8D2A4C8A);
                a = HH(a, b, c, d, x[k + 5], S31, 0xFFFA3942);
                d = HH(d, a, b, c, x[k + 8], S32, 0x8771F681);
                c = HH(c, d, a, b, x[k + 11], S33, 0x6D9D6122);
                b = HH(b, c, d, a, x[k + 14], S34, 0xFDE5380C);
                a = HH(a, b, c, d, x[k + 1], S31, 0xA4BEEA44);
                d = HH(d, a, b, c, x[k + 4], S32, 0x4BDECFA9);
                c = HH(c, d, a, b, x[k + 7], S33, 0xF6BB4B60);
                b = HH(b, c, d, a, x[k + 10], S34, 0xBEBFBC70);
                a = HH(a, b, c, d, x[k + 13], S31, 0x289B7EC6);
                d = HH(d, a, b, c, x[k + 0], S32, 0xEAA127FA);
                c = HH(c, d, a, b, x[k + 3], S33, 0xD4EF3085);
                b = HH(b, c, d, a, x[k + 6], S34, 0x4881D05);
                a = HH(a, b, c, d, x[k + 9], S31, 0xD9D4D039);
                d = HH(d, a, b, c, x[k + 12], S32, 0xE6DB99E5);
                c = HH(c, d, a, b, x[k + 15], S33, 0x1FA27CF8);
                b = HH(b, c, d, a, x[k + 2], S34, 0xC4AC5665);
                a = II(a, b, c, d, x[k + 0], S41, 0xF4292244);
                d = II(d, a, b, c, x[k + 7], S42, 0x432AFF97);
                c = II(c, d, a, b, x[k + 14], S43, 0xAB9423A7);
                b = II(b, c, d, a, x[k + 5], S44, 0xFC93A039);
                a = II(a, b, c, d, x[k + 12], S41, 0x655B59C3);
                d = II(d, a, b, c, x[k + 3], S42, 0x8F0CCC92);
                c = II(c, d, a, b, x[k + 10], S43, 0xFFEFF47D);
                b = II(b, c, d, a, x[k + 1], S44, 0x85845DD1);
                a = II(a, b, c, d, x[k + 8], S41, 0x6FA87E4F);
                d = II(d, a, b, c, x[k + 15], S42, 0xFE2CE6E0);
                c = II(c, d, a, b, x[k + 6], S43, 0xA3014314);
                b = II(b, c, d, a, x[k + 13], S44, 0x4E0811A1);
                a = II(a, b, c, d, x[k + 4], S41, 0xF7537E82);
                d = II(d, a, b, c, x[k + 11], S42, 0xBD3AF235);
                c = II(c, d, a, b, x[k + 2], S43, 0x2AD7D2BB);
                b = II(b, c, d, a, x[k + 9], S44, 0xEB86D391);
                a = AddUnsigned(a, AA); b = AddUnsigned(b, BB); c = AddUnsigned(c, CC); d = AddUnsigned(d, DD);
            }
            if (bit == 32) {
                return WordToHex(a) + WordToHex(b) + WordToHex(c) + WordToHex(d);
            }
            else {
                return WordToHex(b) + WordToHex(c);
            }
        }

var str = ‘测试字符串‘;
str.MD5(); // 默认为16位加密

str.MD5(32);  // 32位加密方法