微信小程序——签名md5加密注意事项

一般在项目中，我们为了保证接口的安全，都会使用签名验证。而生成签名，则需要对排序后的字符串进行md5加密。

然而在微信小程序中，没有自带的md5加密函数，于是我便在百度上寻找了以下代码：

/*  * A JavaScript implementation of the RSA Data Security, Inc. MD5 Message  * Digest Algorithm, as defined in RFC 1321.  * Version 1.1 Copyright (C) Paul Johnston 1999 - 2002.  * Code also contributed by Greg Holt  * See http://pajhome.org.uk/site/legal.html for details.  *//*  * Add integers, wrapping at 2^32. This uses 16-bit operations internally  * to work around bugs in some JS interpreters.  */
function safe_add(x, y) {var lsw = (x & 0xFFFF) + (y & 0xFFFF)var msw = (x >> 16) + (y >> 16) + (lsw >> 16)return (msw << 16) | (lsw & 0xFFFF)
}/*  * Bitwise rotate a 32-bit number to the left.  */
function rol(num, cnt) {return (num << cnt) | (num >>> (32 - cnt))
}/*  * These functions implement the four basic operations the algorithm uses.  */
function cmn(q, a, b, x, s, t) {return safe_add(rol(safe_add(safe_add(a, q), safe_add(x, t)), s), b)
}
function ff(a, b, c, d, x, s, t) {return cmn((b & c) | ((~b) & d), a, b, x, s, t)
}
function gg(a, b, c, d, x, s, t) {return cmn((b & d) | (c & (~d)), a, b, x, s, t)
}
function hh(a, b, c, d, x, s, t) {return cmn(b ^ c ^ d, a, b, x, s, t)
}
function ii(a, b, c, d, x, s, t) {return cmn(c ^ (b | (~d)), a, b, x, s, t)
}/*  * Calculate the MD5 of an array of little-endian words, producing an array  * of little-endian words.  */
function coreMD5(x) {var a = 1732584193var b = -271733879var c = -1732584194var d = 271733878for (var i = 0; i < x.length; i += 16) {var olda = avar oldb = bvar oldc = cvar oldd = da = ff(a, b, c, d, x[i + 0], 7, -680876936)d = ff(d, a, b, c, x[i + 1], 12, -389564586)c = ff(c, d, a, b, x[i + 2], 17, 606105819)b = ff(b, c, d, a, x[i + 3], 22, -1044525330)a = ff(a, b, c, d, x[i + 4], 7, -176418897)d = ff(d, a, b, c, x[i + 5], 12, 1200080426)c = ff(c, d, a, b, x[i + 6], 17, -1473231341)b = ff(b, c, d, a, x[i + 7], 22, -45705983)a = ff(a, b, c, d, x[i + 8], 7, 1770035416)d = ff(d, a, b, c, x[i + 9], 12, -1958414417)c = ff(c, d, a, b, x[i + 10], 17, -42063)b = ff(b, c, d, a, x[i + 11], 22, -1990404162)a = ff(a, b, c, d, x[i + 12], 7, 1804603682)d = ff(d, a, b, c, x[i + 13], 12, -40341101)c = ff(c, d, a, b, x[i + 14], 17, -1502002290)b = ff(b, c, d, a, x[i + 15], 22, 1236535329)a = gg(a, b, c, d, x[i + 1], 5, -165796510)d = gg(d, a, b, c, x[i + 6], 9, -1069501632)c = gg(c, d, a, b, x[i + 11], 14, 643717713)b = gg(b, c, d, a, x[i + 0], 20, -373897302)a = gg(a, b, c, d, x[i + 5], 5, -701558691)d = gg(d, a, b, c, x[i + 10], 9, 38016083)c = gg(c, d, a, b, x[i + 15], 14, -660478335)b = gg(b, c, d, a, x[i + 4], 20, -405537848)a = gg(a, b, c, d, x[i + 9], 5, 568446438)d = gg(d, a, b, c, x[i + 14], 9, -1019803690)c = gg(c, d, a, b, x[i + 3], 14, -187363961)b = gg(b, c, d, a, x[i + 8], 20, 1163531501)a = gg(a, b, c, d, x[i + 13], 5, -1444681467)d = gg(d, a, b, c, x[i + 2], 9, -51403784)c = gg(c, d, a, b, x[i + 7], 14, 1735328473)b = gg(b, c, d, a, x[i + 12], 20, -1926607734)a = hh(a, b, c, d, x[i + 5], 4, -378558)d = hh(d, a, b, c, x[i + 8], 11, -2022574463)c = hh(c, d, a, b, x[i + 11], 16, 1839030562)b = hh(b, c, d, a, x[i + 14], 23, -35309556)a = hh(a, b, c, d, x[i + 1], 4, -1530992060)d = hh(d, a, b, c, x[i + 4], 11, 1272893353)c = hh(c, d, a, b, x[i + 7], 16, -155497632)b = hh(b, c, d, a, x[i + 10], 23, -1094730640)a = hh(a, b, c, d, x[i + 13], 4, 681279174)d = hh(d, a, b, c, x[i + 0], 11, -358537222)c = hh(c, d, a, b, x[i + 3], 16, -722521979)b = hh(b, c, d, a, x[i + 6], 23, 76029189)a = hh(a, b, c, d, x[i + 9], 4, -640364487)d = hh(d, a, b, c, x[i + 12], 11, -421815835)c = hh(c, d, a, b, x[i + 15], 16, 530742520)b = hh(b, c, d, a, x[i + 2], 23, -995338651)a = ii(a, b, c, d, x[i + 0], 6, -198630844)d = ii(d, a, b, c, x[i + 7], 10, 1126891415)c = ii(c, d, a, b, x[i + 14], 15, -1416354905)b = ii(b, c, d, a, x[i + 5], 21, -57434055)a = ii(a, b, c, d, x[i + 12], 6, 1700485571)d = ii(d, a, b, c, x[i + 3], 10, -1894986606)c = ii(c, d, a, b, x[i + 10], 15, -1051523)b = ii(b, c, d, a, x[i + 1], 21, -2054922799)a = ii(a, b, c, d, x[i + 8], 6, 1873313359)d = ii(d, a, b, c, x[i + 15], 10, -30611744)c = ii(c, d, a, b, x[i + 6], 15, -1560198380)b = ii(b, c, d, a, x[i + 13], 21, 1309151649)a = ii(a, b, c, d, x[i + 4], 6, -145523070)d = ii(d, a, b, c, x[i + 11], 10, -1120210379)c = ii(c, d, a, b, x[i + 2], 15, 718787259)b = ii(b, c, d, a, x[i + 9], 21, -343485551)a = safe_add(a, olda)b = safe_add(b, oldb)c = safe_add(c, oldc)d = safe_add(d, oldd)}return [a, b, c, d]
}/*  * Convert an array of little-endian words to a hex string.  */
function binl2hex(binarray) {var hex_tab = "0123456789abcdef"var str = ""for (var i = 0; i < binarray.length * 4; i++) {str += hex_tab.charAt((binarray[i >> 2] >> ((i % 4) * 8 + 4)) & 0xF) +hex_tab.charAt((binarray[i >> 2] >> ((i % 4) * 8)) & 0xF)}return str
}/*  * Convert an array of little-endian words to a base64 encoded string.  */
function binl2b64(binarray) {var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"var str = ""for (var i = 0; i < binarray.length * 32; i += 6) {str += tab.charAt(((binarray[i >> 5] << (i % 32)) & 0x3F) |((binarray[i >> 5 + 1] >> (32 - i % 32)) & 0x3F))}return str
}/*  * Convert an 8-bit character string to a sequence of 16-word blocks, stored  * as an array, and append appropriate padding for MD4/5 calculation.  * If any of the characters are >255, the high byte is silently ignored.  */
function str2binl(str) {var nblk = ((str.length + 8) >> 6) + 1 // number of 16-word blocks    var blks = new Array(nblk * 16)for (var i = 0; i < nblk * 16; i++) blks[i] = 0for (var i = 0; i < str.length; i++)blks[i >> 2] |= (str.charCodeAt(i) & 0xFF) << ((i % 4) * 8)blks[i >> 2] |= 0x80 << ((i % 4) * 8)blks[nblk * 16 - 2] = str.length * 8return blks
}/*  * Convert a wide-character string to a sequence of 16-word blocks, stored as  * an array, and append appropriate padding for MD4/5 calculation.  */
function strw2binl(str) {var nblk = ((str.length + 4) >> 5) + 1 // number of 16-word blocks    var blks = new Array(nblk * 16)for (var i = 0; i < nblk * 16; i++) blks[i] = 0for (var i = 0; i < str.length; i++)blks[i >> 1] |= str.charCodeAt(i) << ((i % 2) * 16)blks[i >> 1] |= 0x80 << ((i % 2) * 16)blks[nblk * 16 - 2] = str.length * 16return blks
}/*  * External interface  */
function hexMD5(str) { return binl2hex(coreMD5(str2binl(str))) }
function hexMD5w(str) { return binl2hex(coreMD5(strw2binl(str))) }
function b64MD5(str) { return binl2b64(coreMD5(str2binl(str))) }
function b64MD5w(str) { return binl2b64(coreMD5(strw2binl(str))) }
/* Backward compatibility */
function calcMD5(str) { return binl2hex(coreMD5(str2binl(str))) }
module.exports = {hexMD5: hexMD5
}    

在使用的过程中，正常的数字以及字母参数都没有出现问题，当涉及的业务需要传递值为中文字符串的参数时，会出现签名错误的问题，即前端和后端在同参数下生成的签名不一样。

一开始我通过将字符串进行url转译后再传给后台的方法来保证签名一致，不过当要后台根据参数插入数据的时候，发现插入的字符串都是url编码，于是我又开始从源头寻找问题的解决办法。

最开始的时候我以为是微信js的编码默认不是utf-8，实际通过对字符串url转译发现和在线utf-8转url的编码是一样的，而且时候也想到，如果编码格式和后台不一样，那么前端转译成的url编码在后台解码后生成的字符肯定是乱码，这才让我想到是md5加密代码的问题。而后，在百度上又寻找了一份优化后的md5加密代码，使用后发现完美解决了当前问题。

以下代码适用于微信小程序中对中文字符串进行md5加密

var rotateLeft = function (lValue, iShiftBits) {return (lValue << iShiftBits) | (lValue >>> (32 - iShiftBits));
}var addUnsigned = function (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);}
}var F = function (x, y, z) {return (x & y) | ((~x) & z);
}var G = function (x, y, z) {return (x & z) | (y & (~z));
}var H = function (x, y, z) {return (x ^ y ^ z);
}var I = function (x, y, z) {return (y ^ (x | (~z)));
}var FF = function (a, b, c, d, x, s, ac) {a = addUnsigned(a, addUnsigned(addUnsigned(F(b, c, d), x), ac));return addUnsigned(rotateLeft(a, s), b);
};var GG = function (a, b, c, d, x, s, ac) {a = addUnsigned(a, addUnsigned(addUnsigned(G(b, c, d), x), ac));return addUnsigned(rotateLeft(a, s), b);
};var HH = function (a, b, c, d, x, s, ac) {a = addUnsigned(a, addUnsigned(addUnsigned(H(b, c, d), x), ac));return addUnsigned(rotateLeft(a, s), b);
};var II = function (a, b, c, d, x, s, ac) {a = addUnsigned(a, addUnsigned(addUnsigned(I(b, c, d), x), ac));return addUnsigned(rotateLeft(a, s), b);
};var convertToWordArray = function (string) {var lWordCount;var lMessageLength = string.length;var lNumberOfWordsTempOne = lMessageLength + 8;var lNumberOfWordsTempTwo = (lNumberOfWordsTempOne - (lNumberOfWordsTempOne % 64)) / 64;var lNumberOfWords = (lNumberOfWordsTempTwo + 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] | (string.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;
};var wordToHex = function (lValue) {var WordToHexValue = "",WordToHexValueTemp = "",lByte, lCount;for (lCount = 0; lCount <= 3; lCount++) {lByte = (lValue >>> (lCount * 8)) & 255;WordToHexValueTemp = "0" + lByte.toString(16);WordToHexValue = WordToHexValue + WordToHexValueTemp.substr(WordToHexValueTemp.length - 2, 2);}return WordToHexValue;
};var uTF8Encode = function (string) {string = string.replace(/\x0d\x0a/g, "\x0a");var output = "";for (var n = 0; n < string.length; n++) {var c = string.charCodeAt(n);if (c < 128) {output += String.fromCharCode(c);} else if ((c > 127) && (c < 2048)) {output += String.fromCharCode((c >> 6) | 192);output += String.fromCharCode((c & 63) | 128);} else {output += String.fromCharCode((c >> 12) | 224);output += String.fromCharCode(((c >> 6) & 63) | 128);output += String.fromCharCode((c & 63) | 128);}}return output;
};function md5(string) {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;string = uTF8Encode(string);x = convertToWordArray(string);a = 0x67452301;b = 0xEFCDAB89;c = 0x98BADCFE;d = 0x10325476;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);}var tempValue = wordToHex(a) + wordToHex(b) + wordToHex(c) + wordToHex(d);return tempValue.toLowerCase();
}module.exports.md5 = md5 

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