JavaScript实现简单MD5加密的脚本分享

1.什么是MD5加密

MD5消息摘要算法(MD5 Message-Digest Algorithm),一种被广泛使用的密码散列函数，可以产生出一个128位（16字节）的散列值（hash value），用于确保信息传输完整一致。
MD5加密是一种不可逆的加密算法，不可逆加密算法的特征是加密过程中不需要使用密钥，输入明文后由系统直接经过加密算法处理成密文，这种加密后的数据是无法被解密的，只有重新输入明文，并再次经过同样不可逆的加密算法处理，得到相同的加密密文并被系统重新识别后，才能真正解密。

2.为什么要使用MD5加密

在存储一些敏感的信息的时候，如果不进行加密则容易出现安全问题。例如：用户存储的密码，如果数据中的密码采用明文，一旦数据库泄露，则用户密码直接泄露。但是使用MD5加密算法之后即使数据泄露，这些密码也无法破解，保证了数据的安全性。

3.实现代码

/*
 md5加密转换脚本
*/

var hexcase = 0;  /* hex output format. 0 - lowercase; 1 - uppercase        */
var b64pad  = ""; /* base-64 pad character. "=" for strict RFC compliance   */
var chrsz   = 8;  /* bits per input character. 8 - ASCII; 16 - Unicode      */

function hex_md5(s){ return binl2hex(core_md5(str2binl(s), s.length * chrsz));}
function b64_md5(s){ return binl2b64(core_md5(str2binl(s), s.length * chrsz));}
function str_md5(s){ return binl2str(core_md5(str2binl(s), s.length * chrsz));}
function hex_hmac_md5(key, data) { return binl2hex(core_hmac_md5(key, data)); }
function b64_hmac_md5(key, data) { return binl2b64(core_hmac_md5(key, data)); }
function str_hmac_md5(key, data) { return binl2str(core_hmac_md5(key, data)); }

function md5_vm_test()
{
 return hex_md5("abc") == "900150983cd24fb0d6963f7d28e17f72";
}

function core_md5(x, len)
{
 /* append padding */
 x[len >> 5] |= 0x80 << ((len) ％ 32);
 x[(((len + 64) >>> 9) << 4) + 14] = len;

var a =  1732584193;
 var b = -271733879;
 var c = -1732584194;
 var d =  271733878;

for(var i = 0; i < x.length; i += 16)
 {
   var olda = a;
   var oldb = b;
   var oldc = c;
   var oldd = d;

a = md5_ff(a, b, c, d, x[i+ 0], 7 , -680876936);
   d = md5_ff(d, a, b, c, x[i+ 1], 12, -389564586);
   c = md5_ff(c, d, a, b, x[i+ 2], 17,  606105819);
   b = md5_ff(b, c, d, a, x[i+ 3], 22, -1044525330);
   a = md5_ff(a, b, c, d, x[i+ 4], 7 , -176418897);
   d = md5_ff(d, a, b, c, x[i+ 5], 12,  1200080426);
   c = md5_ff(c, d, a, b, x[i+ 6], 17, -1473231341);
   b = md5_ff(b, c, d, a, x[i+ 7], 22, -45705983);
   a = md5_ff(a, b, c, d, x[i+ 8], 7 ,  1770035416);
   d = md5_ff(d, a, b, c, x[i+ 9], 12, -1958414417);
   c = md5_ff(c, d, a, b, x[i+10], 17, -42063);
   b = md5_ff(b, c, d, a, x[i+11], 22, -1990404162);
   a = md5_ff(a, b, c, d, x[i+12], 7 ,  1804603682);
   d = md5_ff(d, a, b, c, x[i+13], 12, -40341101);
   c = md5_ff(c, d, a, b, x[i+14], 17, -1502002290);
   b = md5_ff(b, c, d, a, x[i+15], 22,  1236535329);

a = md5_gg(a, b, c, d, x[i+ 1], 5 , -165796510);
   d = md5_gg(d, a, b, c, x[i+ 6], 9 , -1069501632);
   c = md5_gg(c, d, a, b, x[i+11], 14,  643717713);
   b = md5_gg(b, c, d, a, x[i+ 0], 20, -373897302);
   a = md5_gg(a, b, c, d, x[i+ 5], 5 , -701558691);
   d = md5_gg(d, a, b, c, x[i+10], 9 ,  38016083);
   c = md5_gg(c, d, a, b, x[i+15], 14, -660478335);
   b = md5_gg(b, c, d, a, x[i+ 4], 20, -405537848);
   a = md5_gg(a, b, c, d, x[i+ 9], 5 ,  568446438);
   d = md5_gg(d, a, b, c, x[i+14], 9 , -1019803690);
   c = md5_gg(c, d, a, b, x[i+ 3], 14, -187363961);
   b = md5_gg(b, c, d, a, x[i+ 8], 20,  1163531501);
   a = md5_gg(a, b, c, d, x[i+13], 5 , -1444681467);
   d = md5_gg(d, a, b, c, x[i+ 2], 9 , -51403784);
   c = md5_gg(c, d, a, b, x[i+ 7], 14,  1735328473);
   b = md5_gg(b, c, d, a, x[i+12], 20, -1926607734);

a = md5_hh(a, b, c, d, x[i+ 5], 4 , -378558);
   d = md5_hh(d, a, b, c, x[i+ 8], 11, -2022574463);
   c = md5_hh(c, d, a, b, x[i+11], 16,  1839030562);
   b = md5_hh(b, c, d, a, x[i+14], 23, -35309556);
   a = md5_hh(a, b, c, d, x[i+ 1], 4 , -1530992060);
   d = md5_hh(d, a, b, c, x[i+ 4], 11,  1272893353);
   c = md5_hh(c, d, a, b, x[i+ 7], 16, -155497632);
   b = md5_hh(b, c, d, a, x[i+10], 23, -1094730640);
   a = md5_hh(a, b, c, d, x[i+13], 4 ,  681279174);
   d = md5_hh(d, a, b, c, x[i+ 0], 11, -358537222);
   c = md5_hh(c, d, a, b, x[i+ 3], 16, -722521979);
   b = md5_hh(b, c, d, a, x[i+ 6], 23,  76029189);
   a = md5_hh(a, b, c, d, x[i+ 9], 4 , -640364487);
   d = md5_hh(d, a, b, c, x[i+12], 11, -421815835);
   c = md5_hh(c, d, a, b, x[i+15], 16,  530742520);
   b = md5_hh(b, c, d, a, x[i+ 2], 23, -995338651);

a = md5_ii(a, b, c, d, x[i+ 0], 6 , -198630844);
   d = md5_ii(d, a, b, c, x[i+ 7], 10,  1126891415);
   c = md5_ii(c, d, a, b, x[i+14], 15, -1416354905);
   b = md5_ii(b, c, d, a, x[i+ 5], 21, -57434055);
   a = md5_ii(a, b, c, d, x[i+12], 6 ,  1700485571);
   d = md5_ii(d, a, b, c, x[i+ 3], 10, -1894986606);
   c = md5_ii(c, d, a, b, x[i+10], 15, -1051523);
   b = md5_ii(b, c, d, a, x[i+ 1], 21, -2054922799);
   a = md5_ii(a, b, c, d, x[i+ 8], 6 ,  1873313359);
   d = md5_ii(d, a, b, c, x[i+15], 10, -30611744);
   c = md5_ii(c, d, a, b, x[i+ 6], 15, -1560198380);
   b = md5_ii(b, c, d, a, x[i+13], 21,  1309151649);
   a = md5_ii(a, b, c, d, x[i+ 4], 6 , -145523070);
   d = md5_ii(d, a, b, c, x[i+11], 10, -1120210379);
   c = md5_ii(c, d, a, b, x[i+ 2], 15,  718787259);
   b = md5_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 Array(a, b, c, d);

}

/*
* These functions implement the four basic operations the algorithm uses.
*/
function md5_cmn(q, a, b, x, s, t)
{
 return safe_add(bit_rol(safe_add(safe_add(a, q), safe_add(x, t)), s),b);
}
function md5_ff(a, b, c, d, x, s, t)
{
 return md5_cmn((b & c) | ((~b) & d), a, b, x, s, t);
}
function md5_gg(a, b, c, d, x, s, t)
{
 return md5_cmn((b & d) | (c & (~d)), a, b, x, s, t);
}
function md5_hh(a, b, c, d, x, s, t)
{
 return md5_cmn(b ^ c ^ d, a, b, x, s, t);
}
function md5_ii(a, b, c, d, x, s, t)
{
 return md5_cmn(c ^ (b | (~d)), a, b, x, s, t);
}

/*
* Calculate the HMAC-MD5, of a key and some data
*/
function core_hmac_md5(key, data)
{
 var bkey = str2binl(key);
 if(bkey.length > 16) bkey = core_md5(bkey, key.length * chrsz);

var ipad = Array(16), opad = Array(16);
 for(var i = 0; i < 16; i++)
 {
   ipad[i] = bkey[i] ^ 0x36363636;
   opad[i] = bkey[i] ^ 0x5C5C5C5C;
 }

var hash = core_md5(ipad.concat(str2binl(data)), 512 + data.length * chrsz);
 return core_md5(opad.concat(hash), 512 + 128);
}

/*
* 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 bit_rol(num, cnt)
{
 return (num << cnt) | (num >>> (32 - cnt));
}

/*
* Convert a string to an array of little-endian words
* If chrsz is ASCII, characters >255 have their hi-byte silently ignored.
*/
function str2binl(str)
{
 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) << (i％32);
 return bin;
}

/*
* Convert an array of little-endian words to a string
*/
function binl2str(bin)
{
 var str = "";
 var mask = (1 << chrsz) - 1;
 for(var i = 0; i < bin.length * 32; i += chrsz)
   str += String.fromCharCode((bin[i>>5] >>> (i ％ 32)) & mask);
 return str;
}

/*
* Convert an array of little-endian words to a hex string.
*/
function binl2hex(binarray)
{
 var hex_tab = hexcase ? "0123456789ABCDEF" : "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 base-64 string
*/
function binl2b64(binarray)
{
 var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 var str = "";
 for(var i = 0; i < binarray.length * 4; i += 3)
 {
   var triplet = (((binarray[i   >> 2] >> 8 * ( i   ％4)) & 0xFF) << 16)
               | (((binarray[i+1 >> 2] >> 8 * ((i+1)％4)) & 0xFF) << 8 )
               |  ((binarray[i+2 >> 2] >> 8 * ((i+2)％4)) & 0xFF);
   for(var j = 0; j < 4; j++)
   {
     if(i * 8 + j * 6 > binarray.length * 32) str += b64pad;
     else str += tab.charAt((triplet >> 6*(3-j)) & 0x3F);
   }
 }
 return str;
}

来源：https://blog.csdn.net/weixin_46625757/article/details/127371381