一般情况下，js的代码加密用来加密混淆代码，降低代码的可读性，如果一段没有经过任何加密混淆的代码，很容易被第三方或者脚本破解利用，引发许多的安全问题，本文将从以下多个角度讲解，代码加密的一些基本原理**（注意：本文不涉及JS代码的混淆性，只讲解一些基本的JS逆向所需要的代码加密方式）**。

1、对象属性的访问方式

想混淆对象属性的访问方式其实很简单，在JS语法中，直接用.方法可以直接调用方法，也可以使用中括号+方法的形式去调用，中括号内传入一个字符串,这样就改变了对象属性的访问方式了，由于传入的是字符串，所以还可以进一步进行拼接+加密的方式去访问属性。这种方式后文也会讲到。

function Objects(name){this.name = nameObjects.prototype.hello = function(){console.log("hello")}
}
var obj = new Objects("js")
obj.name //"js"
obj["name"] //"js"
obj.hello() // hello
obj["hello"]() // hello

2、十六进制字符串

上述方法讲述了，通过改变对象属性的方式，但即使是这样，代码的可读性仍然比较高，上述方法的字符串仍然可以进行混淆加密处理，字符串可以使用十六进制来表示.

function strtohex(code){var hexstr = [];for (i=0;i<code.length;i++){hexstr += "\\x" + code.charCodeAt(i).toString(16);}return hexstr;
}strtohex("123456")
"\x31\x32\x33\x34\x35\x36"

十六进制的还原方式也非常简单，在控制台直接输出十六进制字符串即可。

3、unicode字符串

除了支持十六进制字符串表示意外，还可以使用unicode字符串形式表示。

function unicode(str){var value='';for (var i = 0; i < str.length; i++) {value += '\\u' + left_zero_4(parseInt(str.charCodeAt(i)).toString(16));}return value;}
function left_zero_4(str) {if (str != null && str != '' && str != 'undefined') {if (str.length == 2) {return '00' + str;}}return str;
}

unicode("123456")
"\u0031\u0032\u0033\u0034\u0035\u0036"

unicode 还原方法

function reconvert(str){ str = str.replace(/(\\u)(\w{1,4})/gi,function($0){ return (String.fromCharCode(parseInt((escape($0).replace(/(%5Cu)(\w{1,4})/g,"$2")),16))); }); str = str.replace(/(&#x)(\w{1,4});/gi,function($0){ return String.fromCharCode(parseInt(escape($0).replace(/(%26%23x)(\w{1,4})(%3B)/g,"$2"),16)); }); str = str.replace(/(&#)(\d{1,6});/gi,function($0){ return String.fromCharCode(parseInt(escape($0).replace(/(%26%23)(\d{1,6})(%3B)/g,"$2"))); }); return str; }

reconvert("\u0031\u0032\u0033\u0034\u0035\u0036")
"123456"

3、ASCLL码混淆

ascll码利用了字符的ascll的转码和解码方式进行混淆，加密和解密方式也非常简单

function strtoascll(code){for (i=0;i<code.length;i++){console.log(code.charCodeAt(i));}}strtoascll("123456")
VM3583:3 49
VM3583:3 50
VM3583:3 51
VM3583:3 52
VM3583:3 53
VM3583:3 54

还原ascll码的话使用String.fromcharcode方法。

String.fromCharCode(49,50,51,52,53,54)
"123456"

4、Base64加密

Base64加密一般都是用于字符串常量加密，在使用前，先把字符串进行加密，一般也多用于一些属性的访问方式,浏览器有自带的Base64编码和解码的函数，atob用来解码，btoa用来编码，把编码后的字符串放入代码中，也需要把解码函数放入才能执行代码

btoa("123")
"MTIz"
atob("MTIz")
"123"

通过这种方式，结合第一小节讲的通过中括号+方法名的方式访问对象属性，可以进一步的进行加密，例如：

function Objects(name){this.name = nameObjects.prototype.hello = function(){console.log("hello")}
}
var obj = new Objects("js")
obj[atob("bmFtZQ==")] //"js"
obj[atob("aGVsbG8=")]() // hello

5、MD5加密

MD5信息摘要算法，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。需要注意的是，MD5加密算法是不可逆的，解密一般都是通过网站的接口.
首先看一下md5的大致加密方式。

/** A JavaScript implementation of the RSA Data Security, Inc. MD5 Message* Digest Algorithm, as defined in RFC 1321.* Version 2.1 Copyright (C) Paul Johnston 1999 - 2002.* Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet* Distributed under the BSD License* See http://pajhome.org.uk/crypt/md5 for more info.*//** Configurable variables. You may need to tweak these to be compatible with* the server-side, but the defaults work in most cases.*/
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      *//** These are the functions you'll usually want to call* They take string arguments and return either hex or base-64 encoded strings*/
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)); }/** Perform a simple self-test to see if the VM is working*/
function md5_vm_test()
{return hex_md5("abc") == "900150983cd24fb0d6963f7d28e17f72";
}/** Calculate the MD5 of an array of little-endian words, and a bit length*/
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;
}

执行完这段代码后，就可以执行加密了

hex_md5("123456");
"e10adc3949ba59abbe56e057f20f883e"

一般来说，这样加密后的字符串会传入后台去比对，由于MD5不可逆，所以加密后的字符串是无法解密的

6、SHA1加密

SHA-1（中文名：安全散列算法1）是一种密码散列函数，美国国家安全局设计，并由美国国家标准技术研究所（NIST）发布为联邦数据处理标准（FIPS）。sha1相比MD5，SHA1所产生的摘要比MD5长32位,安全性更高，一般没有经过高度混淆的JS，sha1加密的关键词就是sha1，下面是sha1加密的源码，sha1同样也是不可逆的

/** [js-sha1]{@link https://github.com/emn178/js-sha1}** @version 0.6.0* @author Chen, Yi-Cyuan [emn178@gmail.com]* @copyright Chen, Yi-Cyuan 2014-2017* @license MIT*/
/*jslint bitwise: true */
(function() {'use strict';var root = typeof window === 'object' ? window : {};var NODE_JS = !root.JS_SHA1_NO_NODE_JS && typeof process === 'object' && process.versions && process.versions.node;if (NODE_JS) {root = global;}var COMMON_JS = !root.JS_SHA1_NO_COMMON_JS && typeof module === 'object' && module.exports;var AMD = typeof define === 'function' && define.amd;var HEX_CHARS = '0123456789abcdef'.split('');var EXTRA = [-2147483648, 8388608, 32768, 128];var SHIFT = [24, 16, 8, 0];var OUTPUT_TYPES = ['hex', 'array', 'digest', 'arrayBuffer'];var blocks = [];var createOutputMethod = function (outputType) {return function (message) {return new Sha1(true).update(message)[outputType]();};};var createMethod = function () {var method = createOutputMethod('hex');if (NODE_JS) {method = nodeWrap(method);}method.create = function () {return new Sha1();};method.update = function (message) {return method.create().update(message);};for (var i = 0; i < OUTPUT_TYPES.length; ++i) {var type = OUTPUT_TYPES[i];method[type] = createOutputMethod(type);}return method;};var nodeWrap = function (method) {var crypto = eval("require('crypto')");var Buffer = eval("require('buffer').Buffer");var nodeMethod = function (message) {if (typeof message === 'string') {return crypto.createHash('sha1').update(message, 'utf8').digest('hex');} else if (message.constructor === ArrayBuffer) {message = new Uint8Array(message);} else if (message.length === undefined) {return method(message);}return crypto.createHash('sha1').update(new Buffer(message)).digest('hex');};return nodeMethod;};function Sha1(sharedMemory) {if (sharedMemory) {blocks[0] = blocks[16] = blocks[1] = blocks[2] = blocks[3] =blocks[4] = blocks[5] = blocks[6] = blocks[7] =blocks[8] = blocks[9] = blocks[10] = blocks[11] =blocks[12] = blocks[13] = blocks[14] = blocks[15] = 0;this.blocks = blocks;} else {this.blocks = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];}this.h0 = 0x67452301;this.h1 = 0xEFCDAB89;this.h2 = 0x98BADCFE;this.h3 = 0x10325476;this.h4 = 0xC3D2E1F0;this.block = this.start = this.bytes = this.hBytes = 0;this.finalized = this.hashed = false;this.first = true;}Sha1.prototype.update = function (message) {if (this.finalized) {return;}var notString = typeof(message) !== 'string';if (notString && message.constructor === root.ArrayBuffer) {message = new Uint8Array(message);}var code, index = 0, i, length = message.length || 0, blocks = this.blocks;while (index < length) {if (this.hashed) {this.hashed = false;blocks[0] = this.block;blocks[16] = blocks[1] = blocks[2] = blocks[3] =blocks[4] = blocks[5] = blocks[6] = blocks[7] =blocks[8] = blocks[9] = blocks[10] = blocks[11] =blocks[12] = blocks[13] = blocks[14] = blocks[15] = 0;}if(notString) {for (i = this.start; index < length && i < 64; ++index) {blocks[i >> 2] |= message[index] << SHIFT[i++ & 3];}} else {for (i = this.start; index < length && i < 64; ++index) {code = message.charCodeAt(index);if (code < 0x80) {blocks[i >> 2] |= code << SHIFT[i++ & 3];} else if (code < 0x800) {blocks[i >> 2] |= (0xc0 | (code >> 6)) << SHIFT[i++ & 3];blocks[i >> 2] |= (0x80 | (code & 0x3f)) << SHIFT[i++ & 3];} else if (code < 0xd800 || code >= 0xe000) {blocks[i >> 2] |= (0xe0 | (code >> 12)) << SHIFT[i++ & 3];blocks[i >> 2] |= (0x80 | ((code >> 6) & 0x3f)) << SHIFT[i++ & 3];blocks[i >> 2] |= (0x80 | (code & 0x3f)) << SHIFT[i++ & 3];} else {code = 0x10000 + (((code & 0x3ff) << 10) | (message.charCodeAt(++index) & 0x3ff));blocks[i >> 2] |= (0xf0 | (code >> 18)) << SHIFT[i++ & 3];blocks[i >> 2] |= (0x80 | ((code >> 12) & 0x3f)) << SHIFT[i++ & 3];blocks[i >> 2] |= (0x80 | ((code >> 6) & 0x3f)) << SHIFT[i++ & 3];blocks[i >> 2] |= (0x80 | (code & 0x3f)) << SHIFT[i++ & 3];}}}this.lastByteIndex = i;this.bytes += i - this.start;if (i >= 64) {this.block = blocks[16];this.start = i - 64;this.hash();this.hashed = true;} else {this.start = i;}}if (this.bytes > 4294967295) {this.hBytes += this.bytes / 4294967296 << 0;this.bytes = this.bytes % 4294967296;}return this;};Sha1.prototype.finalize = function () {if (this.finalized) {return;}this.finalized = true;var blocks = this.blocks, i = this.lastByteIndex;blocks[16] = this.block;blocks[i >> 2] |= EXTRA[i & 3];this.block = blocks[16];if (i >= 56) {if (!this.hashed) {this.hash();}blocks[0] = this.block;blocks[16] = blocks[1] = blocks[2] = blocks[3] =blocks[4] = blocks[5] = blocks[6] = blocks[7] =blocks[8] = blocks[9] = blocks[10] = blocks[11] =blocks[12] = blocks[13] = blocks[14] = blocks[15] = 0;}blocks[14] = this.hBytes << 3 | this.bytes >>> 29;blocks[15] = this.bytes << 3;this.hash();};Sha1.prototype.hash = function () {var a = this.h0, b = this.h1, c = this.h2, d = this.h3, e = this.h4;var f, j, t, blocks = this.blocks;for(j = 16; j < 80; ++j) {t = blocks[j - 3] ^ blocks[j - 8] ^ blocks[j - 14] ^ blocks[j - 16];blocks[j] =  (t << 1) | (t >>> 31);}for(j = 0; j < 20; j += 5) {f = (b & c) | ((~b) & d);t = (a << 5) | (a >>> 27);e = t + f + e + 1518500249 + blocks[j] << 0;b = (b << 30) | (b >>> 2);f = (a & b) | ((~a) & c);t = (e << 5) | (e >>> 27);d = t + f + d + 1518500249 + blocks[j + 1] << 0;a = (a << 30) | (a >>> 2);f = (e & a) | ((~e) & b);t = (d << 5) | (d >>> 27);c = t + f + c + 1518500249 + blocks[j + 2] << 0;e = (e << 30) | (e >>> 2);f = (d & e) | ((~d) & a);t = (c << 5) | (c >>> 27);b = t + f + b + 1518500249 + blocks[j + 3] << 0;d = (d << 30) | (d >>> 2);f = (c & d) | ((~c) & e);t = (b << 5) | (b >>> 27);a = t + f + a + 1518500249 + blocks[j + 4] << 0;c = (c << 30) | (c >>> 2);}for(; j < 40; j += 5) {f = b ^ c ^ d;t = (a << 5) | (a >>> 27);e = t + f + e + 1859775393 + blocks[j] << 0;b = (b << 30) | (b >>> 2);f = a ^ b ^ c;t = (e << 5) | (e >>> 27);d = t + f + d + 1859775393 + blocks[j + 1] << 0;a = (a << 30) | (a >>> 2);f = e ^ a ^ b;t = (d << 5) | (d >>> 27);c = t + f + c + 1859775393 + blocks[j + 2] << 0;e = (e << 30) | (e >>> 2);f = d ^ e ^ a;t = (c << 5) | (c >>> 27);b = t + f + b + 1859775393 + blocks[j + 3] << 0;d = (d << 30) | (d >>> 2);f = c ^ d ^ e;t = (b << 5) | (b >>> 27);a = t + f + a + 1859775393 + blocks[j + 4] << 0;c = (c << 30) | (c >>> 2);}for(; j < 60; j += 5) {f = (b & c) | (b & d) | (c & d);t = (a << 5) | (a >>> 27);e = t + f + e - 1894007588 + blocks[j] << 0;b = (b << 30) | (b >>> 2);f = (a & b) | (a & c) | (b & c);t = (e << 5) | (e >>> 27);d = t + f + d - 1894007588 + blocks[j + 1] << 0;a = (a << 30) | (a >>> 2);f = (e & a) | (e & b) | (a & b);t = (d << 5) | (d >>> 27);c = t + f + c - 1894007588 + blocks[j + 2] << 0;e = (e << 30) | (e >>> 2);f = (d & e) | (d & a) | (e & a);t = (c << 5) | (c >>> 27);b = t + f + b - 1894007588 + blocks[j + 3] << 0;d = (d << 30) | (d >>> 2);f = (c & d) | (c & e) | (d & e);t = (b << 5) | (b >>> 27);a = t + f + a - 1894007588 + blocks[j + 4] << 0;c = (c << 30) | (c >>> 2);}for(; j < 80; j += 5) {f = b ^ c ^ d;t = (a << 5) | (a >>> 27);e = t + f + e - 899497514 + blocks[j] << 0;b = (b << 30) | (b >>> 2);f = a ^ b ^ c;t = (e << 5) | (e >>> 27);d = t + f + d - 899497514 + blocks[j + 1] << 0;a = (a << 30) | (a >>> 2);f = e ^ a ^ b;t = (d << 5) | (d >>> 27);c = t + f + c - 899497514 + blocks[j + 2] << 0;e = (e << 30) | (e >>> 2);f = d ^ e ^ a;t = (c << 5) | (c >>> 27);b = t + f + b - 899497514 + blocks[j + 3] << 0;d = (d << 30) | (d >>> 2);f = c ^ d ^ e;t = (b << 5) | (b >>> 27);a = t + f + a - 899497514 + blocks[j + 4] << 0;c = (c << 30) | (c >>> 2);}this.h0 = this.h0 + a << 0;this.h1 = this.h1 + b << 0;this.h2 = this.h2 + c << 0;this.h3 = this.h3 + d << 0;this.h4 = this.h4 + e << 0;};Sha1.prototype.hex = function () {this.finalize();var h0 = this.h0, h1 = this.h1, h2 = this.h2, h3 = this.h3, h4 = this.h4;return HEX_CHARS[(h0 >> 28) & 0x0F] + HEX_CHARS[(h0 >> 24) & 0x0F] +HEX_CHARS[(h0 >> 20) & 0x0F] + HEX_CHARS[(h0 >> 16) & 0x0F] +HEX_CHARS[(h0 >> 12) & 0x0F] + HEX_CHARS[(h0 >> 8) & 0x0F] +HEX_CHARS[(h0 >> 4) & 0x0F] + HEX_CHARS[h0 & 0x0F] +HEX_CHARS[(h1 >> 28) & 0x0F] + HEX_CHARS[(h1 >> 24) & 0x0F] +HEX_CHARS[(h1 >> 20) & 0x0F] + HEX_CHARS[(h1 >> 16) & 0x0F] +HEX_CHARS[(h1 >> 12) & 0x0F] + HEX_CHARS[(h1 >> 8) & 0x0F] +HEX_CHARS[(h1 >> 4) & 0x0F] + HEX_CHARS[h1 & 0x0F] +HEX_CHARS[(h2 >> 28) & 0x0F] + HEX_CHARS[(h2 >> 24) & 0x0F] +HEX_CHARS[(h2 >> 20) & 0x0F] + HEX_CHARS[(h2 >> 16) & 0x0F] +HEX_CHARS[(h2 >> 12) & 0x0F] + HEX_CHARS[(h2 >> 8) & 0x0F] +HEX_CHARS[(h2 >> 4) & 0x0F] + HEX_CHARS[h2 & 0x0F] +HEX_CHARS[(h3 >> 28) & 0x0F] + HEX_CHARS[(h3 >> 24) & 0x0F] +HEX_CHARS[(h3 >> 20) & 0x0F] + HEX_CHARS[(h3 >> 16) & 0x0F] +HEX_CHARS[(h3 >> 12) & 0x0F] + HEX_CHARS[(h3 >> 8) & 0x0F] +HEX_CHARS[(h3 >> 4) & 0x0F] + HEX_CHARS[h3 & 0x0F] +HEX_CHARS[(h4 >> 28) & 0x0F] + HEX_CHARS[(h4 >> 24) & 0x0F] +HEX_CHARS[(h4 >> 20) & 0x0F] + HEX_CHARS[(h4 >> 16) & 0x0F] +HEX_CHARS[(h4 >> 12) & 0x0F] + HEX_CHARS[(h4 >> 8) & 0x0F] +HEX_CHARS[(h4 >> 4) & 0x0F] + HEX_CHARS[h4 & 0x0F];};Sha1.prototype.toString = Sha1.prototype.hex;Sha1.prototype.digest = function () {this.finalize();var h0 = this.h0, h1 = this.h1, h2 = this.h2, h3 = this.h3, h4 = this.h4;return [(h0 >> 24) & 0xFF, (h0 >> 16) & 0xFF, (h0 >> 8) & 0xFF, h0 & 0xFF,(h1 >> 24) & 0xFF, (h1 >> 16) & 0xFF, (h1 >> 8) & 0xFF, h1 & 0xFF,(h2 >> 24) & 0xFF, (h2 >> 16) & 0xFF, (h2 >> 8) & 0xFF, h2 & 0xFF,(h3 >> 24) & 0xFF, (h3 >> 16) & 0xFF, (h3 >> 8) & 0xFF, h3 & 0xFF,(h4 >> 24) & 0xFF, (h4 >> 16) & 0xFF, (h4 >> 8) & 0xFF, h4 & 0xFF];};Sha1.prototype.array = Sha1.prototype.digest;Sha1.prototype.arrayBuffer = function () {this.finalize();var buffer = new ArrayBuffer(20);var dataView = new DataView(buffer);dataView.setUint32(0, this.h0);dataView.setUint32(4, this.h1);dataView.setUint32(8, this.h2);dataView.setUint32(12, this.h3);dataView.setUint32(16, this.h4);return buffer;};var exports = createMethod();if (COMMON_JS) {module.exports = exports;} else {root.sha1 = exports;if (AMD) {define(function () {return exports;});}}
})();

执行完代码后，直接运行sha1加密代码

sha1("123456")
"7c4a8d09ca3762af61e59520943dc26494f8941b"

7、数值常量加密

算法加密过程中，也会使用到数值，可以看到，以上算法中，在算法的加密过程中，也会用到一些数值常量，通常我们也会使用搜索常量的方式来确定是哪种加密方式，不过，这种常量也可以进行加密混淆，他可以写成任意进制类型，也可以使用其他的简单加密，可以使用位异或的特性来加密，如果 a ^ b = c 那么， c ^ b = a, 用这种方式，可以取代加密算法中的常量。下面是一个简单的例子

1 ^ 2  = 3 // 3
1 = 3 ^ 2 # 这里的常量1 就可以用 3 ^ 2的方式来替代

除开上面的异或，也可能使用多种混淆方式结合使用。

JS逆向 代码加密方式任重而道远，下一篇讲讲述AES对称加密、RSA非对称加密，整体替换，AAEncode加密和其他加密方式