Analysis on the MD5 method of WeChat applet

This article mainly introduces the detailed explanation of the MD5 method of the WeChat applet and the relevant information of the example code. Friends in need can refer to the following

The detailed explanation of the MD5 method of the WeChat applet

The generated files can be placed in the utils file! ! !

/* 
 * 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 = 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 = 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] = 0  
 for(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 * 8  
 return 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] = 0  
 for(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 * 16  
 return 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  
}

Usage:

var utilMd5 = require('../../utils/md5.js');  
var password = utilMd5.hexMD5(password);

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