文章目录
前言
逆向是学习爬虫必不可少的一个部分，JS逆向的掌握可以解决绝大多数网站加密机制，以下就从一个小案例中入手JS逆向吧。
一、JS逆向以及PyExecJS模块介绍
1、JS逆向
在数据加密的情况下，我们通过目标网站的JS数据加密算法，反向推导出该算法的加密过程，这个过程我们称之为JS逆向。
2、PyEecJS
在python中能够运行JS代码的模块。
二、使用步骤
1、环境安装
安装PyExecJS模块
安装成功后，最好重启下cmd终端和pycharm，或者重启电脑
pip install PyExecJS安装node.js开发环境（官网链接 https://nodejs.org/en/）
安装node.js是为了让程序有一个比较良好的JS运行引擎
若无法访问官网，可从该网盘下载
链接：https://pan.baidu.com/s/15dJnead7mxmc6dhtMXz2Kg
提取码：zw01
选择LTS版本下载（LTS为长期支持版，版本稳定）
以下是安装步骤，一步一部照着来就可以
检查是否安装成功：
在CMD里面输入如下指令
node -v
npm -v
显示版本号及说明安装成功！ （安装好了之后，记得重启电脑）
验证execjs的JS引擎是否正确
打开PyCharm,新建一个.py文件
在代码界面输入以下代码，
import execjs
print(execjs.get().name)显示如下，则证明正确
Node.js (V8)
2.PyExecJS使用步骤
1、导入模块
2、创建node对象
3、打开JS文件
4、使用compile命令把JS文件转成一个JS对象
5、生成要执行的JS语句（字符串形式）
6、调用eval函数，执行定义好的JS代码
模板如下（示例）：
#导包
import execjs
#创建node对象
node = execjs.get()
#编译即将被执行的js代码对应的文件，返回上下文对象ctx
#js文件应该在对象执行之前被打开
fp = open("js文件目录",encoding='utf-8')
ctx = node.compile(fp.read())
#生成要执行的js函数调用的字符串形式
funName = 'getPwd("xxx")'
#两种执行JS代码的方式
# execjs.eval() eval方法中，整个函数调用包含在字符串内
# execjs.exec_() call方法中，第一个参数是函数名（str）,后面接参数
#基于ctx对象调用eval函数，执行上一条语句定义的JS代码
result = ctx.eval(funName)三、网易云逆向思路分析
接下来将的内容，请忽视具体代码的实现，重点专注逆向的分析思路！！！
1、首先要打开你浏览器的无痕窗口
无痕窗口不会保存任何浏览历史、搜索历史、下载历史、表单历史、cookie 或者 Internet临时文件，这样有利于你对网站的判断。
2、关于两种JS逆向思路
以下讲述的是两种JS逆向思路，有麻烦一些的操作，也有简单一些的操作，各有各的优缺点，两种方式可以应用在不同的逆向作业上，希望大家都可以掌握这两种思路，这样就可以处理大多数的网站。
3、方案一、缺啥补啥型（比较万能的方案，适合绝大多数网站）
具体操作方案如下
（1）定位数据包
网易的歌曲随便挑一首即可（https://music.163.com/#/song?id=484056997）
第一步：进入到你挑选好的目标网址。
第二步：打开发者工具，点击Network。
第三步：点击下方的Fetch\XHR。
第四步：点击播放歌曲。
第五步：点位到最上层的数据包。
第六步：点击Preview。
（2）分析数据包
查看每一个数据包，在Preview中找是否存在该歌曲的播放链接
这里定位到名为···v1?csrf_token=····的数据包携带了相关音乐的播放链接
注：如若遇到两个及以上的相同数据包，则要查看每个数据包链接是否可以播放，若可以播放，则默认选择最上面的数据包进行逆向分析。
我们查看以下这个链接的真实性
这里看到可以正常的播放 ，验证了我们抓包的准确性。
这里我们看一下该数据包的数据是否被加密，这里我们看到有两个参数是被加密了
还要记住该数据包的url地址
https://music.163.com/weapi/song/enhance/player/url/v1?csrf_token=
（3）分析栈结构
点击Initiator，这里看到许多的链接，Initiator类似栈操作
就是从最上层函数起，逐级追寻调用到他的函数名
点击最上层的链接，进入到该文件的源码，点击 { } 格式化代码
可以看到，格式化完代码后，有一行代码被标注成黄色，而且光标也会停在这个位置
此时我们需要在本行前面打上断点（只需要在数字上点击以下即可打上断点）
接下来我们点击播放按钮，发现程序停在了我们打断点的位置，说明有数据产生或者是有数据的值被更改。
此时我们选中arguments，鼠标放在上面，会看到数据的值
我们接着分析其他文件，若发生了数据改变的文件，则证明该文件是加密数据的文件
我们查看所有的文件发现，当我们查看该文件的时候发现数据是加密的
但是下一个文件时，数据是没有被加密，由此可得，加密数据的算法在该文件中
所以我们逆向的主要工作就要还原该算法的实现过程
（4）分析t6n.be7X文件，还原算法过程
这里点击释放断点的时候，要注意Y6S的变化，要与之前记录该数据包的地址相同才可以
https://music.163.com/weapi/song/enhance/player/url/v1?csrf_token=
我们分析一下该语句
var bKB6v = window.asrsea(JSON.stringify(i3x), buU3x(["流泪", "强"]), buU3x(Rg9X.md), buU3x(["爱心", "女孩", "惊恐", "大笑"]));
在此语句中，window.asrsea一共有四个变量，其中buU3x(["流泪", "强"])与buU3x(["爱心", "女孩", "惊恐", "大笑"])是固定了，参数写死了，剩下的两个是不固定的，所以我们把切入点放在JSON.stringify(i3x)的参数i3x中，以及buU3x(Rg9X.md)的参数Rg9X.md中。
（5）开始编写逆向JS代码
打开PyCharm，新建一个JS文件，准好之后我们正式开始逆向代码的完成。
把鼠标放在JSON.stringify(i3x)的参数i3x上，看到它未加密之前的数据
把i3x复制到Console中查看，拿到它的数据，并且放在JS代码中
var i3x ={
ids: '[484056997]',
level: 'standard',
encodeType: 'aac',
csrf_token: ''
}还原buU3x
var buU3x = function(chL0x) {
var m3x = [];
j3x.bg4k(chL0x, function(chE0x) {
m3x.push(Rg9X.emj[chE0x])
});
return m3x.join("")
};在JS代码，没有的函数它会有波浪线，我们按照上面的方法，把缺失的函数补上即可
（同样的道理，选中缺失的函数，跳转到目标地址，然后把函数的实现过程复制到js代码中）
以下是第一段缺啥补啥补出来的代码
var JW7P = function(i3x, v3x) {
try {
v3x = v3x.toLowerCase();
if (i3x === null)
return v3x == "null";
if (i3x === undefined)
return v3x == "undefined";
return {}.toString.call(i3x).toLowerCase() == "[object " + v3x + "]"
} catch (e) {
return !1
}
};
var gV6P = function(i3x) {
return JW7P(i3x, "function")
};
var bg4k = function(k3x, cG4K, O4S) {
if (!k3x || !k3x.length || !gV6P(cG4K))
return this;
if (!!k3x.forEach) {
k3x.forEach(cG4K, O4S);
return this
}
}
var emj = {
"色": "00e0b",
"流感": "509f6",
"这边": "259df",
"弱": "8642d",
"嘴唇": "bc356",
"亲": "62901",
"开心": "477df",
"呲牙": "22677",
"憨笑": "ec152",
"猫": "b5ff6",
"皱眉": "8ace6",
"幽灵": "15bb7",
"蛋糕": "b7251",
"发怒": "52b3a",
"大哭": "b17a8",
"兔子": "76aea",
"星星": "8a5aa",
"钟情": "76d2e",
"牵手": "41762",
"公鸡": "9ec4e",
"爱意": "e341f",
"禁止": "56135",
"狗": "fccf6",
"亲亲": "95280",
"叉": "104e0",
"礼物": "312ec",
"晕": "bda92",
"呆": "557c9",
"生病": "38701",
"钻石": "14af6",
"拜": "c9d05",
"怒": "c4f7f",
"示爱": "0c368",
"汗": "5b7a4",
"小鸡": "6bee2",
"痛苦": "55932",
"撇嘴": "575cc",
"惶恐": "e10b4",
"口罩": "24d81",
"吐舌": "3cfe4",
"心碎": "875d3",
"生气": "e8204",
"可爱": "7b97d",
"鬼脸": "def52",
"跳舞": "741d5",
"男孩": "46b8e",
"奸笑": "289dc",
"猪": "6935b",
"圈": "3ece0",
"便便": "462db",
"外星": "0a22b",
"圣诞": "8e7",
"流泪": "01000",
"强": "1",
"爱心": "0CoJU",
"女孩": "m6Qyw",
"惊恐": "8W8ju",
"大笑": "d"
};
var buU3x = function(chL0x) {
var m3x = [];
bg4k(chL0x, function(chE0x) {
m3x.push(emj[chE0x])
});
return m3x.join("")
};
var i3x ={
ids: '[484056997]',
level: 'standard',
encodeType: 'aac',
csrf_token: ''
}
此时我们测试buU3x，看一下是否与代码中加载的一样
在上面代码中加入一条语句
console.log(buU3x(["流泪", "强"]));显示010001则证明这个参数逆向成功
这里测试第二个参数md
加入一条语句
console.log(buU3x(md)) 得到相同的结果，证明该参数逆向成功
现在来逆向window.asrsea
思路跟逆向其他参数是一样的，选中window.asrsea，查看源代码，缺啥补啥
补到CryptoJS.enc.Utf8.parse这个位置时，可以采用第三方库导入，这样可以减少工作量
因为CryptoJS时JS的第三方库，以后遇到第三方库时也采用此方法
npm install crypto-js（要在此目录下的Terminal进行安装）
下图是打开此目录下的Terminal的方法
如下是安装成功的
综上逆向过程
代码总过程应该为
//CryptoJS公开的第三方库，使用npm安装
function setMaxDigits(a) {
maxDigits = a,
ZERO_ARRAY = new Array(maxDigits);
for (var b = 0; b < ZERO_ARRAY.length; b++)
ZERO_ARRAY[b] = 0;
bigZero = new BigInt,
bigOne = new BigInt,
bigOne.digits[0] = 1
}
function BigInt(a) {
this.digits = "boolean" == typeof a && 1 == a ? null : ZERO_ARRAY.slice(0),
this.isNeg = !1
}
function biFromDecimal(a) {
for (var d, e, f, b = "-" == a.charAt(0), c = b ? 1 : 0; c < a.length && "0" == a.charAt(c); )
++c;
if (c == a.length)
d = new BigInt;
else {
for (e = a.length - c,
f = e % dpl10,
0 == f && (f = dpl10),
d = biFromNumber(Number(a.substr(c, f))),
c += f; c < a.length; )
d = biAdd(biMultiply(d, lr10), biFromNumber(Number(a.substr(c, dpl10)))),
c += dpl10;
d.isNeg = b
}
return d
}
function biCopy(a) {
var b = new BigInt(!0);
return b.digits = a.digits.slice(0),
b.isNeg = a.isNeg,
b
}
function biFromNumber(a) {
var c, b = new BigInt;
for (b.isNeg = 0 > a,
a = Math.abs(a),
c = 0; a > 0; )
b.digits[c++] = a & maxDigitVal,
a >>= biRadixBits;
return b
}
function reverseStr(a) {
var c, b = "";
for (c = a.length - 1; c > -1; --c)
b += a.charAt(c);
return b
}
function biToString(a, b) {
var d, e, c = new BigInt;
for (c.digits[0] = b,
d = biDivideModulo(a, c),
e = hexatrigesimalToChar[d[1].digits[0]]; 1 == biCompare(d[0], bigZero); )
d = biDivideModulo(d[0], c),
digit = d[1].digits[0],
e += hexatrigesimalToChar[d[1].digits[0]];
return (a.isNeg ? "-" : "") + reverseStr(e)
}
function biToDecimal(a) {
var c, d, b = new BigInt;
for (b.digits[0] = 10,
c = biDivideModulo(a, b),
d = String(c[1].digits[0]); 1 == biCompare(c[0], bigZero); )
c = biDivideModulo(c[0], b),
d += String(c[1].digits[0]);
return (a.isNeg ? "-" : "") + reverseStr(d)
}
function digitToHex(a) {
var b = 15
, c = "";
for (i = 0; 4 > i; ++i)
c += hexToChar[a & b],
a >>>= 4;
return reverseStr(c)
}
function biToHex(a) {
var d, b = "";
for (biHighIndex(a),
d = biHighIndex(a); d > -1; --d)
b += digitToHex(a.digits[d]);
return b
}
function charToHex(a) {
var h, b = 48, c = b + 9, d = 97, e = d + 25, f = 65, g = 90;
return h = a >= b && c >= a ? a - b : a >= f && g >= a ? 10 + a - f : a >= d && e >= a ? 10 + a - d : 0
}
function hexToDigit(a) {
var d, b = 0, c = Math.min(a.length, 4);
for (d = 0; c > d; ++d)
b <<= 4,
b |= charToHex(a.charCodeAt(d));
return b
}
function biFromHex(a) {
var d, e, b = new BigInt, c = a.length;
for (d = c,
e = 0; d > 0; d -= 4,
++e)
b.digits[e] = hexToDigit(a.substr(Math.max(d - 4, 0), Math.min(d, 4)));
return b
}
function biFromString(a, b) {
var g, h, i, j, c = "-" == a.charAt(0), d = c ? 1 : 0, e = new BigInt, f = new BigInt;
for (f.digits[0] = 1,
g = a.length - 1; g >= d; g--)
h = a.charCodeAt(g),
i = charToHex(h),
j = biMultiplyDigit(f, i),
e = biAdd(e, j),
f = biMultiplyDigit(f, b);
return e.isNeg = c,
e
}
function biDump(a) {
return (a.isNeg ? "-" : "") + a.digits.join(" ")
}
function biAdd(a, b) {
var c, d, e, f;
if (a.isNeg != b.isNeg)
b.isNeg = !b.isNeg,
c = biSubtract(a, b),
b.isNeg = !b.isNeg;
else {
for (c = new BigInt,
d = 0,
f = 0; f < a.digits.length; ++f)
e = a.digits[f] + b.digits[f] + d,
c.digits[f] = 65535 & e,
d = Number(e >= biRadix);
c.isNeg = a.isNeg
}
return c
}
function biSubtract(a, b) {
var c, d, e, f;
if (a.isNeg != b.isNeg)
b.isNeg = !b.isNeg,
c = biAdd(a, b),
b.isNeg = !b.isNeg;
else {
for (c = new BigInt,
e = 0,
f = 0; f < a.digits.length; ++f)
d = a.digits[f] - b.digits[f] + e,
c.digits[f] = 65535 & d,
c.digits[f] < 0 && (c.digits[f] += biRadix),
e = 0 - Number(0 > d);
if (-1 == e) {
for (e = 0,
f = 0; f < a.digits.length; ++f)
d = 0 - c.digits[f] + e,
c.digits[f] = 65535 & d,
c.digits[f] < 0 && (c.digits[f] += biRadix),
e = 0 - Number(0 > d);
c.isNeg = !a.isNeg
} else
c.isNeg = a.isNeg
}
return c
}
function biHighIndex(a) {
for (var b = a.digits.length - 1; b > 0 && 0 == a.digits[b]; )
--b;
return b
}
function biNumBits(a) {
var e, b = biHighIndex(a), c = a.digits[b], d = (b + 1) * bitsPerDigit;
for (e = d; e > d - bitsPerDigit && 0 == (32768 & c); --e)
c <<= 1;
return e
}
function biMultiply(a, b) {
var d, h, i, k, c = new BigInt, e = biHighIndex(a), f = biHighIndex(b);
for (k = 0; f >= k; ++k) {
for (d = 0,
i = k,
j = 0; e >= j; ++j,
++i)
h = c.digits[i] + a.digits[j] * b.digits[k] + d,
c.digits[i] = h & maxDigitVal,
d = h >>> biRadixBits;
c.digits[k + e + 1] = d
}
return c.isNeg = a.isNeg != b.isNeg,
c
}
function biMultiplyDigit(a, b) {
var c, d, e, f;
for (result = new BigInt,
c = biHighIndex(a),
d = 0,
f = 0; c >= f; ++f)
e = result.digits[f] + a.digits[f] * b + d,
result.digits[f] = e & maxDigitVal,
d = e >>> biRadixBits;
return result.digits[1 + c] = d,
result
}
function arrayCopy(a, b, c, d, e) {
var g, h, f = Math.min(b + e, a.length);
for (g = b,
h = d; f > g; ++g,
++h)
c[h] = a[g]
}
function biShiftLeft(a, b) {
var e, f, g, h, c = Math.floor(b / bitsPerDigit), d = new BigInt;
for (arrayCopy(a.digits, 0, d.digits, c, d.digits.length - c),
e = b % bitsPerDigit,
f = bitsPerDigit - e,
g = d.digits.length - 1,
h = g - 1; g > 0; --g,
--h)
d.digits[g] = d.digits[g] << e & maxDigitVal | (d.digits[h] & highBitMasks[e]) >>> f;
return d.digits[0] = d.digits[g] << e & maxDigitVal,
d.isNeg = a.isNeg,
d
}
function biShiftRight(a, b) {
var e, f, g, h, c = Math.floor(b / bitsPerDigit), d = new BigInt;
for (arrayCopy(a.digits, c, d.digits, 0, a.digits.length - c),
e = b % bitsPerDigit,
f = bitsPerDigit - e,
g = 0,
h = g + 1; g < d.digits.length - 1; ++g,
++h)
d.digits[g] = d.digits[g] >>> e | (d.digits[h] & lowBitMasks[e]) << f;
return d.digits[d.digits.length - 1] >>>= e,
d.isNeg = a.isNeg,
d
}
function biMultiplyByRadixPower(a, b) {
var c = new BigInt;
return arrayCopy(a.digits, 0, c.digits, b, c.digits.length - b),
c
}
function biDivideByRadixPower(a, b) {
var c = new BigInt;
return arrayCopy(a.digits, b, c.digits, 0, c.digits.length - b),
c
}
function biModuloByRadixPower(a, b) {
var c = new BigInt;
return arrayCopy(a.digits, 0, c.digits, 0, b),
c
}
function biCompare(a, b) {
if (a.isNeg != b.isNeg)
return 1 - 2 * Number(a.isNeg);
for (var c = a.digits.length - 1; c >= 0; --c)
if (a.digits[c] != b.digits[c])
return a.isNeg ? 1 - 2 * Number(a.digits[c] > b.digits[c]) : 1 - 2 * Number(a.digits[c] < b.digits[c]);
return 0
}
function biDivideModulo(a, b) {
var f, g, h, i, j, k, l, m, n, o, p, q, r, s, c = biNumBits(a), d = biNumBits(b), e = b.isNeg;
if (d > c)
return a.isNeg ? (f = biCopy(bigOne),
f.isNeg = !b.isNeg,
a.isNeg = !1,
b.isNeg = !1,
g = biSubtract(b, a),
a.isNeg = !0,
b.isNeg = e) : (f = new BigInt,
g = biCopy(a)),
new Array(f,g);
for (f = new BigInt,
g = a,
h = Math.ceil(d / bitsPerDigit) - 1,
i = 0; b.digits[h] < biHalfRadix; )
b = biShiftLeft(b, 1),
++i,
++d,
h = Math.ceil(d / bitsPerDigit) - 1;
for (g = biShiftLeft(g, i),
c += i,
j = Math.ceil(c / bitsPerDigit) - 1,
k = biMultiplyByRadixPower(b, j - h); -1 != biCompare(g, k); )
++f.digits[j - h],
g = biSubtract(g, k);
for (l = j; l > h; --l) {
for (m = l >= g.digits.length ? 0 : g.digits[l],
n = l - 1 >= g.digits.length ? 0 : g.digits[l - 1],
o = l - 2 >= g.digits.length ? 0 : g.digits[l - 2],
p = h >= b.digits.length ? 0 : b.digits[h],
q = h - 1 >= b.digits.length ? 0 : b.digits[h - 1],
f.digits[l - h - 1] = m == p ? maxDigitVal : Math.floor((m * biRadix + n) / p),
r = f.digits[l - h - 1] * (p * biRadix + q),
s = m * biRadixSquared + (n * biRadix + o); r > s; )
--f.digits[l - h - 1],
r = f.digits[l - h - 1] * (p * biRadix | q),
s = m * biRadix * biRadix + (n * biRadix + o);
k = biMultiplyByRadixPower(b, l - h - 1),
g = biSubtract(g, biMultiplyDigit(k, f.digits[l - h - 1])),
g.isNeg && (g = biAdd(g, k),
--f.digits[l - h - 1])
}
return g = biShiftRight(g, i),
f.isNeg = a.isNeg != e,
a.isNeg && (f = e ? biAdd(f, bigOne) : biSubtract(f, bigOne),
b = biShiftRight(b, i),
g = biSubtract(b, g)),
0 == g.digits[0] && 0 == biHighIndex(g) && (g.isNeg = !1),
new Array(f,g)
}
function biDivide(a, b) {
return biDivideModulo(a, b)[0]
}
function biModulo(a, b) {
return biDivideModulo(a, b)[1]
}
function biMultiplyMod(a, b, c) {
return biModulo(biMultiply(a, b), c)
}
function biPow(a, b) {
for (var c = bigOne, d = a; ; ) {
if (0 != (1 & b) && (c = biMultiply(c, d)),
b >>= 1,
0 == b)
break;
d = biMultiply(d, d)
}
return c
}
function biPowMod(a, b, c) {
for (var d = bigOne, e = a, f = b; ; ) {
if (0 != (1 & f.digits[0]) && (d = biMultiplyMod(d, e, c)),
f = biShiftRight(f, 1),
0 == f.digits[0] && 0 == biHighIndex(f))
break;
e = biMultiplyMod(e, e, c)
}
return d
}
function BarrettMu(a) {
this.modulus = biCopy(a),
this.k = biHighIndex(this.modulus) + 1;
var b = new BigInt;
b.digits[2 * this.k] = 1,
this.mu = biDivide(b, this.modulus),
this.bkplus1 = new BigInt,
this.bkplus1.digits[this.k + 1] = 1,
this.modulo = BarrettMu_modulo,
this.multiplyMod = BarrettMu_multiplyMod,
this.powMod = BarrettMu_powMod
}
function BarrettMu_modulo(a) {
var i, b = biDivideByRadixPower(a, this.k - 1), c = biMultiply(b, this.mu), d = biDivideByRadixPower(c, this.k + 1), e = biModuloByRadixPower(a, this.k + 1), f = biMultiply(d, this.modulus), g = biModuloByRadixPower(f, this.k + 1), h = biSubtract(e, g);
for (h.isNeg && (h = biAdd(h, this.bkplus1)),
i = biCompare(h, this.modulus) >= 0; i; )
h = biSubtract(h, this.modulus),
i = biCompare(h, this.modulus) >= 0;
return h
}
function BarrettMu_multiplyMod(a, b) {
var c = biMultiply(a, b);
return this.modulo(c)
}
function BarrettMu_powMod(a, b) {
var d, e, c = new BigInt;
for (c.digits[0] = 1,
d = a,
e = b; ; ) {
if (0 != (1 & e.digits[0]) && (c = this.multiplyMod(c, d)),
e = biShiftRight(e, 1),
0 == e.digits[0] && 0 == biHighIndex(e))
break;
d = this.multiplyMod(d, d)
}
return c
}
var maxDigits, ZERO_ARRAY, bigZero, bigOne, dpl10, lr10, hexatrigesimalToChar, hexToChar, highBitMasks, lowBitMasks, biRadixBase = 2, biRadixBits = 16, bitsPerDigit = biRadixBits, biRadix = 65536, biHalfRadix = biRadix >>> 1, biRadixSquared = biRadix * biRadix, maxDigitVal = biRadix - 1, maxInteger = 9999999999999998;
setMaxDigits(20),
dpl10 = 15,
lr10 = biFromNumber(1e15),
hexatrigesimalToChar = new Array("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"),
hexToChar = new Array("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"),
highBitMasks = new Array(0,32768,49152,57344,61440,63488,64512,65024,65280,65408,65472,65504,65520,65528,65532,65534,65535),
lowBitMasks = new Array(0,1,3,7,15,31,63,127,255,511,1023,2047,4095,8191,16383,32767,65535);
function RSAKeyPair(a, b, c) {
this.e = biFromHex(a),
this.d = biFromHex(b),
this.m = biFromHex(c),
this.chunkSize = 2 * biHighIndex(this.m),
this.radix = 16,
this.barrett = new BarrettMu(this.m)
}
function c(a, b, c) {
var d, e;
return setMaxDigits(131),
d = new RSAKeyPair(b,"",c),
e = encryptedString(d, a)
}
function encryptedString(a, b) {
for (var f, g, h, i, j, k, l, c = new Array, d = b.length, e = 0; d > e; )
c[e] = b.charCodeAt(e),
e++;
for (; 0 != c.length % a.chunkSize; )
c[e++] = 0;
for (f = c.length,
g = "",
e = 0; f > e; e += a.chunkSize) {
for (j = new BigInt,
h = 0,
i = e; i < e + a.chunkSize; ++h)
j.digits[h] = c[i++],
j.digits[h] += c[i++] << 8;
k = a.barrett.powMod(j, a.e),
l = 16 == a.radix ? biToHex(k) : biToString(k, a.radix),
g += l + " "
}
return g.substring(0, g.length - 1)
}
// 导入模块
var CryptoJS = require("crypto-js");
function b(a, b) {
var c = CryptoJS.enc.Utf8.parse(b)
, d = CryptoJS.enc.Utf8.parse("0102030405060708")
, e = CryptoJS.enc.Utf8.parse(a)
, f = CryptoJS.AES.encrypt(e, c, {
iv: d,
mode: CryptoJS.mode.CBC
});
return f.toString()
}
function a(a) {
var d, e, b = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789", c = "";
for (d = 0; a > d; d += 1)
e = Math.random() * b.length,
e = Math.floor(e),
c += b.charAt(e);
return c
}
function d(d, e, f, g) {
var h = {}, i = a(16);
return h.encText = b(d, g),
h.encText = b(h.encText, i),
h.encSecKey = c(i, e, f),
h
}
var JW7P = function(i3x, v3x) {
try {
v3x = v3x.toLowerCase();
if (i3x === null)
return v3x == "null";
if (i3x === undefined)
return v3x == "undefined";
return {}.toString.call(i3x).toLowerCase() == "[object " + v3x + "]"
} catch (e) {
return !1
}
};
var gV6P = function(i3x) {
return JW7P(i3x, "function")
};
var bg4k = function(k3x, cG4K, O4S) {
if (!k3x || !k3x.length || !gV6P(cG4K))
return this;
if (!!k3x.forEach) {
k3x.forEach(cG4K, O4S);
return this
}
};
var emj = {
"色": "00e0b",
"流感": "509f6",
"这边": "259df",
"弱": "8642d",
"嘴唇": "bc356",
"亲": "62901",
"开心": "477df",
"呲牙": "22677",
"憨笑": "ec152",
"猫": "b5ff6",
"皱眉": "8ace6",
"幽灵": "15bb7",
"蛋糕": "b7251",
"发怒": "52b3a",
"大哭": "b17a8",
"兔子": "76aea",
"星星": "8a5aa",
"钟情": "76d2e",
"牵手": "41762",
"公鸡": "9ec4e",
"爱意": "e341f",
"禁止": "56135",
"狗": "fccf6",
"亲亲": "95280",
"叉": "104e0",
"礼物": "312ec",
"晕": "bda92",
"呆": "557c9",
"生病": "38701",
"钻石": "14af6",
"拜": "c9d05",
"怒": "c4f7f",
"示爱": "0c368",
"汗": "5b7a4",
"小鸡": "6bee2",
"痛苦": "55932",
"撇嘴": "575cc",
"惶恐": "e10b4",
"口罩": "24d81",
"吐舌": "3cfe4",
"心碎": "875d3",
"生气": "e8204",
"可爱": "7b97d",
"鬼脸": "def52",
"跳舞": "741d5",
"男孩": "46b8e",
"奸笑": "289dc",
"猪": "6935b",
"圈": "3ece0",
"便便": "462db",
"外星": "0a22b",
"圣诞": "8e7",
"流泪": "01000",
"强": "1",
"爱心": "0CoJU",
"女孩": "m6Qyw",
"惊恐": "8W8ju",
"大笑": "d"
};
var md = ["色", "流感", "这边", "弱", "嘴唇", "亲", "开心", "呲牙", "憨笑", "猫", "皱眉", "幽灵", "蛋糕", "发怒", "大哭", "兔子", "星星", "钟情", "牵手", "公鸡", "爱意", "禁止", "狗", "亲亲", "叉", "礼物", "晕", "呆", "生病", "钻石", "拜", "怒", "示爱", "汗", "小鸡", "痛苦", "撇嘴", "惶恐", "口罩", "吐舌", "心碎", "生气", "可爱", "鬼脸", "跳舞", "男孩", "奸笑", "猪", "圈", "便便", "外星", "圣诞"];
var buU3x = function(chL0x) {
var m3x = [];
bg4k(chL0x, function(chE0x) {
m3x.push(emj[chE0x])
});
return m3x.join("")
};
// var i3x ={
// ids: '[484056997]',
// level: 'standard',
// encodeType: 'aac',
// csrf_token: ''
// }
// console.log(buU3x(["流泪", "强"]));
// console.log(buU3x(md))
// console.log(d(JSON.stringify(i3x),buU3x(["流泪", "强"]),buU3x(md), buU3x(["爱心", "女孩", "惊恐", "大笑"])))
function fn(i3x){
return d(JSON.stringify(i3x),buU3x(["流泪", "强"]),buU3x(md), buU3x(["爱心", "女孩", "惊恐", "大笑"]));
}（6）此时我们来编写python代码
#以下三行代码是用来解决gbk报错的，它需要在导入模块之前导入
import subprocess
from functools import partial
subprocess.Popen = partial(subprocess.Popen, encoding='utf-8')
import execjs
import requests
#该首歌的参数
data = {
"ids": '[484056997]',
"level": 'standard',
"encodeType": 'aac',
"csrf_token": ''
}
#创建node对象：
node = execjs.get()
#编译即将被执行的js代码对应的文件，返回上下文对象js
f = open("music163.js", mode="r", encoding="utf-8")
js = execjs.compile(f.read())
#基于js调用call函数，模拟执行js文件中的fn函数
r = js.call("fn", data)
#上面请求到r的参数还不是我们想要的
#在原始数据包中，encText对应的数据应该是params，需要对数据做一下更改
real_data = {
"params": r["encText"],
"encSecKey": r["encSecKey"]
}
#目标数据包地址
url = "https://music.163.com/weapi/song/enhance/player/url/v1?csrf_token="
#请求头参数
headers={
"user-agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36"
}
#发生请求得到响应
response = requests.post(url=url, headers=headers,data=real_data)
print(response.text)执行结果应该为：
到此为止，逆向过程完全结束
下节预告
网易云逆向的第二种思维--全局搜索法
总结
上述我们从PyExecJS模块的基本用法开始讲述,到node.js的安装，从逆向第一种思维缺啥补啥，分析了网易云逆向的基本思路。以上就算是逆向的基本入门了，虽然这只是一种比较笨拙的做法，但是它的准确率是比较高的。下一节我会讲述逆向的另外一种思维方式，想要学好逆向，躬体力行才是真!
望各位学者朋友提出问题，帮助我及时改正，若有雷同之处，纯属巧合，联系我改之！
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