解析md5算法

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  • MD5实现128bit的Hash值的密码散列函数
  1. MD5的作用
  • 在传输的时候,进行加密,防止恶意窃取数据。
  1. MD5算法的原理:
  • 填充输入信息,使其字节长度对512求余数为448.
  • 信息的长度扩展为N*512+448 bit N为整数。然后将每个512bit的组分为16个32bit子分组,最后经过一系列的算法生成4个32bit共128bit的散列值
  1. MD5算法的实现:

     1 /* eslint-disable */
    
     2 var jQuery = require('jquery');
     3 (function($){
     4   var rotateLeft = function(lValue, iShiftBits) {
     5     return (lValue << iShiftBits) | (lValue >>> (32 - iShiftBits));
     6   }
     7   var addUnsigned = function(lX, lY) {
     8     var lX4, lY4, lX8, lY8, lResult;
     9     lX8 = (lX & 0x80000000);
     10     lY8 = (lY & 0x80000000);
     11     lX4 = (lX & 0x40000000);
     12     lY4 = (lY & 0x40000000);
     13     lResult = (lX & 0x3FFFFFFF) + (lY & 0x3FFFFFFF);
     14     if (lX4 & lY4) return (lResult ^ 0x80000000 ^ lX8 ^ lY8);
     15     if (lX4 | lY4) {
     16       if (lResult & 0x40000000) return (lResult ^ 0xC0000000 ^ lX8 ^ lY8);
     17       else return (lResult ^ 0x40000000 ^ lX8 ^ lY8);
     18     } else {
     19       return (lResult ^ lX8 ^ lY8);
     20     }
     21   }
     22   var F = function(x, y, z) {
     23     return (x & y) | ((~ x) & z);
     24   }
     25   var G = function(x, y, z) {
     26     return (x & z) | (y & (~ z));
     27   }
     28   var H = function(x, y, z) {
     29     return (x ^ y ^ z);
     30   }
     31   var I = function(x, y, z) {
     32     return (y ^ (x | (~ z)));
     33   }
     34   var FF = function(a, b, c, d, x, s, ac) {
     35     a = addUnsigned(a, addUnsigned(addUnsigned(F(b, c, d), x), ac));
     36     return addUnsigned(rotateLeft(a, s), b);
     37   };
     38   var GG = function(a, b, c, d, x, s, ac) {
     39     a = addUnsigned(a, addUnsigned(addUnsigned(G(b, c, d), x), ac));
     40     return addUnsigned(rotateLeft(a, s), b);
     41   };
     42   var HH = function(a, b, c, d, x, s, ac) {
     43     a = addUnsigned(a, addUnsigned(addUnsigned(H(b, c, d), x), ac));
     44     return addUnsigned(rotateLeft(a, s), b);
     45   };
     46   var II = function(a, b, c, d, x, s, ac) {
     47     a = addUnsigned(a, addUnsigned(addUnsigned(I(b, c, d), x), ac));
     48     return addUnsigned(rotateLeft(a, s), b);
     49   };
     50   var convertToWordArray = function(string) {
     51     var lWordCount;
     52     var lMessageLength = string.length;
     53     var lNumberOfWordsTempOne = lMessageLength + 8;
     54     var lNumberOfWordsTempTwo = (lNumberOfWordsTempOne - (lNumberOfWordsTempOne % 64)) / 64;
     55     var lNumberOfWords = (lNumberOfWordsTempTwo + 1) * 16;
     56     var lWordArray = Array(lNumberOfWords - 1);
     57     var lBytePosition = 0;
     58     var lByteCount = 0;
     59     while (lByteCount < lMessageLength) {
     60       lWordCount = (lByteCount - (lByteCount % 4)) / 4;
     61       lBytePosition = (lByteCount % 4) * 8;
     62       lWordArray[lWordCount] = (lWordArray[lWordCount] | (string.charCodeAt(lByteCount) << lBytePosition));
     63       lByteCount++;
     64     }
     65     lWordCount = (lByteCount - (lByteCount % 4)) / 4;
     66     lBytePosition = (lByteCount % 4) * 8;
     67     lWordArray[lWordCount] = lWordArray[lWordCount] | (0x80 << lBytePosition);
     68     lWordArray[lNumberOfWords - 2] = lMessageLength << 3;
     69     lWordArray[lNumberOfWords - 1] = lMessageLength >>> 29;
     70     return lWordArray;
     71   };
     72   var wordToHex = function(lValue) {
     73     var WordToHexValue = "", WordToHexValueTemp = "", lByte, lCount;
     74     for (lCount = 0; lCount <= 3; lCount++) {
     75       lByte = (lValue >>> (lCount * 8)) & 255;
     76       WordToHexValueTemp = "0" + lByte.toString(16);
     77       WordToHexValue = WordToHexValue + WordToHexValueTemp.substr(WordToHexValueTemp.length - 2, 2);
     78     }
     79     return WordToHexValue;
     80   };
     81   var uTF8Encode = function(string) {
     82     string = string.replace(/\x0d\x0a/g, "\x0a");
     83     var output = "";
     84     for (var n = 0; n < string.length; n++) {
     85       var c = string.charCodeAt(n);
     86       if (c < 128) {
     87         output += String.fromCharCode(c);
     88       } else if ((c > 127) && (c < 2048)) {
     89         output += String.fromCharCode((c >> 6) | 192);
     90         output += String.fromCharCode((c & 63) | 128);
     91       } else {
     92         output += String.fromCharCode((c >> 12) | 224);
     93         output += String.fromCharCode(((c >> 6) & 63) | 128);
     94         output += String.fromCharCode((c & 63) | 128);
     95       }
     96     }
     97     return output;
     98   };
     99   $.extend({
     100     md5: function(string) {
     101       var x = Array();
     102       var k, AA, BB, CC, DD, a, b, c, d;
     103       var S11=7, S12=12, S13=17, S14=22;
     104       var S21=5, S22=9 , S23=14, S24=20;
     105       var S31=4, S32=11, S33=16, S34=23;
     106       var S41=6, S42=10, S43=15, S44=21;
     107       string = uTF8Encode(string);
     108       x = convertToWordArray(string);
     109       a = 0x67452301; b = 0xEFCDAB89; c = 0x98BADCFE; d = 0x10325476;
     110       for (k = 0; k < x.length; k += 16) {
     111         AA = a; BB = b; CC = c; DD = d;
     112         a = FF(a, b, c, d, x[k+0],  S11, 0xD76AA478);
     113         d = FF(d, a, b, c, x[k+1],  S12, 0xE8C7B756);
     114         c = FF(c, d, a, b, x[k+2],  S13, 0x242070DB);
     115         b = FF(b, c, d, a, x[k+3],  S14, 0xC1BDCEEE);
     116         a = FF(a, b, c, d, x[k+4],  S11, 0xF57C0FAF);
     117         d = FF(d, a, b, c, x[k+5],  S12, 0x4787C62A);
     118         c = FF(c, d, a, b, x[k+6],  S13, 0xA8304613);
     119         b = FF(b, c, d, a, x[k+7],  S14, 0xFD469501);
     120         a = FF(a, b, c, d, x[k+8],  S11, 0x698098D8);
     121         d = FF(d, a, b, c, x[k+9],  S12, 0x8B44F7AF);
     122         c = FF(c, d, a, b, x[k+10], S13, 0xFFFF5BB1);
     123         b = FF(b, c, d, a, x[k+11], S14, 0x895CD7BE);
     124         a = FF(a, b, c, d, x[k+12], S11, 0x6B901122);
     125         d = FF(d, a, b, c, x[k+13], S12, 0xFD987193);
     126         c = FF(c, d, a, b, x[k+14], S13, 0xA679438E);
     127         b = FF(b, c, d, a, x[k+15], S14, 0x49B40821);
     128         a = GG(a, b, c, d, x[k+1],  S21, 0xF61E2562);
     129         d = GG(d, a, b, c, x[k+6],  S22, 0xC040B340);
     130         c = GG(c, d, a, b, x[k+11], S23, 0x265E5A51);
     131         b = GG(b, c, d, a, x[k+0],  S24, 0xE9B6C7AA);
     132         a = GG(a, b, c, d, x[k+5],  S21, 0xD62F105D);
     133         d = GG(d, a, b, c, x[k+10], S22, 0x2441453);
     134         c = GG(c, d, a, b, x[k+15], S23, 0xD8A1E681);
     135         b = GG(b, c, d, a, x[k+4],  S24, 0xE7D3FBC8);
     136         a = GG(a, b, c, d, x[k+9],  S21, 0x21E1CDE6);
     137         d = GG(d, a, b, c, x[k+14], S22, 0xC33707D6);
     138         c = GG(c, d, a, b, x[k+3],  S23, 0xF4D50D87);
     139         b = GG(b, c, d, a, x[k+8],  S24, 0x455A14ED);
     140         a = GG(a, b, c, d, x[k+13], S21, 0xA9E3E905);
     141         d = GG(d, a, b, c, x[k+2],  S22, 0xFCEFA3F8);
     142         c = GG(c, d, a, b, x[k+7],  S23, 0x676F02D9);
     143         b = GG(b, c, d, a, x[k+12], S24, 0x8D2A4C8A);
     144         a = HH(a, b, c, d, x[k+5],  S31, 0xFFFA3942);
     145         d = HH(d, a, b, c, x[k+8],  S32, 0x8771F681);
     146         c = HH(c, d, a, b, x[k+11], S33, 0x6D9D6122);
     147         b = HH(b, c, d, a, x[k+14], S34, 0xFDE5380C);
     148         a = HH(a, b, c, d, x[k+1],  S31, 0xA4BEEA44);
     149         d = HH(d, a, b, c, x[k+4],  S32, 0x4BDECFA9);
     150         c = HH(c, d, a, b, x[k+7],  S33, 0xF6BB4B60);
     151         b = HH(b, c, d, a, x[k+10], S34, 0xBEBFBC70);
     152         a = HH(a, b, c, d, x[k+13], S31, 0x289B7EC6);
     153         d = HH(d, a, b, c, x[k+0],  S32, 0xEAA127FA);
     154         c = HH(c, d, a, b, x[k+3],  S33, 0xD4EF3085);
     155         b = HH(b, c, d, a, x[k+6],  S34, 0x4881D05);
     156         a = HH(a, b, c, d, x[k+9],  S31, 0xD9D4D039);
     157         d = HH(d, a, b, c, x[k+12], S32, 0xE6DB99E5);
     158         c = HH(c, d, a, b, x[k+15], S33, 0x1FA27CF8);
     159         b = HH(b, c, d, a, x[k+2],  S34, 0xC4AC5665);
     160         a = II(a, b, c, d, x[k+0],  S41, 0xF4292244);
     161         d = II(d, a, b, c, x[k+7],  S42, 0x432AFF97);
     162         c = II(c, d, a, b, x[k+14], S43, 0xAB9423A7);
     163         b = II(b, c, d, a, x[k+5],  S44, 0xFC93A039);
     164         a = II(a, b, c, d, x[k+12], S41, 0x655B59C3);
     165         d = II(d, a, b, c, x[k+3],  S42, 0x8F0CCC92);
     166         c = II(c, d, a, b, x[k+10], S43, 0xFFEFF47D);
     167         b = II(b, c, d, a, x[k+1],  S44, 0x85845DD1);
     168         a = II(a, b, c, d, x[k+8],  S41, 0x6FA87E4F);
     169         d = II(d, a, b, c, x[k+15], S42, 0xFE2CE6E0);
     170         c = II(c, d, a, b, x[k+6],  S43, 0xA3014314);
     171         b = II(b, c, d, a, x[k+13], S44, 0x4E0811A1);
     172         a = II(a, b, c, d, x[k+4],  S41, 0xF7537E82);
     173         d = II(d, a, b, c, x[k+11], S42, 0xBD3AF235);
     174         c = II(c, d, a, b, x[k+2],  S43, 0x2AD7D2BB);
     175         b = II(b, c, d, a, x[k+9],  S44, 0xEB86D391);
     176         a = addUnsigned(a, AA);
     177         b = addUnsigned(b, BB);
     178         c = addUnsigned(c, CC);
     179         d = addUnsigned(d, DD);
     180       }
     181       var tempValue = wordToHex(a) + wordToHex(b) + wordToHex(c) + wordToHex(d);
     182       return tempValue.toLowerCase();
     183     }
     184   });
     185 })(jQuery);