在前端常见的加密方式中AES很少使用，因为相对于非对称的RSA安全性很低，AES是典型的对称加密，密钥就在前端源码里。
案列网站是http://ewt360.com，一个并不复杂的网站，首先抓个包看看：

加密字段只有password，粗略一看挺像MD5的加密方式，但是看看源码，有明确的key

复制加密函数在调试工具中试试：

其中引用函数只有几十行代码：
var com_str = {
_KEY: "20171109124536982017110912453698",//32位
_IV: "2017110912453698",//16位
/**************************************************************
*字符串加密
* str：需要加密的字符串****************************************************************/
Encrypt: function (str) {
var key = CryptoJS.enc.Utf8.parse(this._KEY);
var iv = CryptoJS.enc.Utf8.parse(this._IV);
var encrypted = '';
var srcs = CryptoJS.enc.Utf8.parse(str);
encrypted = CryptoJS.AES.encrypt(srcs, key, {
iv: iv,
mode: CryptoJS.mode.CBC,
padding: CryptoJS.pad.Pkcs7
});
return encrypted.ciphertext.toString();
},
/**************************************************************
*字符串解密
* str：需要解密的字符串****************************************************************/
Decrypt: function (str) {
var key = CryptoJS.enc.Utf8.parse(this._KEY);
var iv = CryptoJS.enc.Utf8.parse(this._IV);
var encryptedHexStr = CryptoJS.enc.Hex.parse(str);
var srcs = CryptoJS.enc.Base64.stringify(encryptedHexStr);
var decrypt = CryptoJS.AES.decrypt(srcs, key, {
iv: iv,
mode: CryptoJS.mode.CBC,
padding: CryptoJS.pad.Pkcs7
});
var decryptedStr = decrypt.toString(CryptoJS.enc.Utf8);
return decryptedStr.toString();
}
}
其中CryptoJS是加密的核心类，在另一个js文件中，需要来将两个js合并，CryptoJS如下：
/*
CryptoJS v3.1.2http://code.google.com/p/crypto-js
(c) 2009-2013 by Jeff Mott. All rights reserved.http://code.google.com/p/crypto-js/wiki/License
*/
var CryptoJS = CryptoJS || function(u, p) {
var d = {}
, l = d.lib = {}
, s = function() {}
, t = l.Base = {
extend: function(a) {
s.prototype = this;
var c = new s;
a && c.mixIn(a);
c.hasOwnProperty("init") || (c.init = function() {
c.$super.init.apply(this, arguments)
}
);
c.init.prototype = c;
c.$super = this;
return c
},
create: function() {
var a = this.extend();
a.init.apply(a, arguments);
return a
},
init: function() {},
mixIn: function(a) {
for (var c in a)
a.hasOwnProperty(c) && (this[c] = a[c]);
a.hasOwnProperty("toString") && (this.toString = a.toString)
},
clone: function() {
return this.init.prototype.extend(this)
}
}
, r = l.WordArray = t.extend({
init: function(a, c) {
a = this.words = a || [];
this.sigBytes = c != p ? c : 4 * a.length
},
toString: function(a) {
return (a || v).stringify(this)
},
concat: function(a) {
var c = this.words
, e = a.words
, j = this.sigBytes;
a = a.sigBytes;
this.clamp();
if (j % 4)
for (var k = 0; k < a; k++)
c[j + k >>> 2] |= (e[k >>> 2] >>> 24 - 8 * (k % 4) & 255) << 24 - 8 * ((j + k) % 4);
else if (65535 < e.length)
for (k = 0; k < a; k += 4)
c[j + k >>> 2] = e[k >>> 2];
else
c.push.apply(c, e);
this.sigBytes += a;
return this
},
clamp: function() {
var a = this.words
, c = this.sigBytes;
a[c >>> 2] &= 4294967295 << 32 - 8 * (c % 4);
a.length = u.ceil(c / 4)
},
clone: function() {
var a = t.clone.call(this);
a.words = this.words.slice(0);
return a
},
random: function(a) {
for (var c = [], e = 0; e < a; e += 4)
c.push(4294967296 * u.random() | 0);
return new r.init(c,a)
}
})
, w = d.enc = {}
, v = w.Hex = {
stringify: function(a) {
var c = a.words;
a = a.sigBytes;
for (var e = [], j = 0; j < a; j++) {
·········
上面便是一个ＡＥＳ加密的实例，至于ｐｙｔｈｏｎ如何实现，已经在ｐｙｔｈｏｎ加密全家桶里面《Python实现DES、DES3、AES、RSA、MD5、SHA、HMAC加密方式及示例》，感兴趣可以看看。