爬虫逆向实战（十三）--某课网登录
一、数据接口分析
主页地址：某课网
1、抓包
通过抓包可以发现登录接口是user/login
2、判断是否有加密参数
- 请求参数是否加密？
通过查看“载荷”模块可以发现有一个password加密参数，还有一个browser_key这个可以写死不需要关心
- 请求头是否加密？
无 - 响应是否加密？
无 - cookie是否加密？
无
二、加密位置定位
1、看启动器
查看启动器发现里面有一个SSOController.login，点进去查看
点进去之后可以发现，上方有对password的处理，可以怀疑此处就是加密位置
在此处打断点，再次点击登录发现可以断住，并且window.btoa(e)的结果就是密文，所以可以断定此处就是加密位置
三、扣js代码
将定位到的加密位置的代码扣出，缺啥补啥。
但是当我扣代码时会发现缺少一些参数以及加密密钥，此时我们可以观察抓包发现，网站是请求了prelogin接口获取的。
所以我们需要先请求这个prelogin接口，获取到这些参数，然后使用这些参数对密码进行加密，再发包请求登录接口即可
源代码：
var K = function(a, f) {
function e(b) {
N = b;
G = Array(N);
for (b = 0; b < G.length; b++)
G[b] = 0;
new h;
E = new h;
E.digits[0] = 1
}
function h(b) {
this.digits = "boolean" == typeof b && 1 == b ? null : G.slice(0);
this.isNeg = !1
}
function u(b) {
var c = new h(!0);
c.digits = b.digits.slice(0);
c.isNeg = b.isNeg;
return c
}
function k(b) {
for (var c = new h, r = b.length, d = 0; 0 < r; r -= 4,
++d) {
for (var a = c.digits, O = d, g = b.substr(Math.max(r - 4, 0), Math.min(r, 4)), e = 0, f = Math.min(g.length, 4), l = 0; l < f; ++l) {
e <<= 4;
var n = g.charCodeAt(l);
e |= 48 <= n && 57 >= n ? n - 48 : 65 <= n && 90 >= n ? 10 + n - 65 : 97 <= n && 122 >= n ? 10 + n - 97 : 0
}
a[O] = e
}
return c
}
function w(b, c) {
if (b.isNeg != c.isNeg) {
c.isNeg = !c.isNeg;
var r = l(b, c);
c.isNeg = !c.isNeg
} else {
r = new h;
for (var d = 0, a = 0; a < b.digits.length; ++a)
d = b.digits[a] + c.digits[a] + d,
r.digits[a] = d & 65535,
d = Number(65536 <= d);
r.isNeg = b.isNeg
}
return r
}
function l(b, c) {
if (b.isNeg != c.isNeg) {
c.isNeg = !c.isNeg;
var r = w(b, c);
c.isNeg = !c.isNeg
} else {
r = new h;
for (var a, m = a = 0; m < b.digits.length; ++m)
a = b.digits[m] - c.digits[m] + a,
r.digits[m] = a & 65535,
0 > r.digits[m] && (r.digits[m] += 65536),
a = 0 - Number(0 > a);
if (-1 == a) {
for (m = a = 0; m < b.digits.length; ++m)
a = 0 - r.digits[m] + a,
r.digits[m] = a & 65535,
0 > r.digits[m] && (r.digits[m] += 65536),
a = 0 - Number(0 > a);
r.isNeg = !b.isNeg
} else
r.isNeg = b.isNeg
}
return r
}
function n(b) {
for (var c = b.digits.length - 1; 0 < c && 0 == b.digits[c]; )
--c;
return c
}
function v(b) {
var c = n(b);
b = b.digits[c];
c = 16 * (c + 1);
var a;
for (a = c; a > c - 16 && 0 == (b & 32768); --a)
b <<= 1;
return a
}
function t(b, c) {
for (var a = new h, d, m = n(b), e = n(c), g, f = 0; f <= e; ++f) {
d = 0;
g = f;
for (j = 0; j <= m; ++j,
++g)
d = a.digits[g] + b.digits[j] * c.digits[f] + d,
a.digits[g] = d & 65535,
d >>>= 16;
a.digits[f + m + 1] = d
}
a.isNeg = b.isNeg != c.isNeg;
return a
}
function p(b, c, a, d, m) {
for (m = Math.min(c + m, b.length); c < m; ++c,
++d)
a[d] = b[c]
}
function y(b, c) {
var a = Math.floor(c / 16)
, d = new h;
p(b.digits, 0, d.digits, a, d.digits.length - a);
c %= 16;
a = 16 - c;
for (var m = d.digits.length - 1, e = m - 1; 0 < m; --m,
--e)
d.digits[m] = d.digits[m] << c & 65535 | (d.digits[e] & P[c]) >>> a;
d.digits[0] = d.digits[m] << c & 65535;
d.isNeg = b.isNeg;
return d
}
function L(b, a) {
var c = Math.floor(a / 16)
, d = new h;
p(b.digits, c, d.digits, 0, b.digits.length - c);
a %= 16;
c = 16 - a;
for (var e = 0, f = e + 1; e < d.digits.length - 1; ++e,
++f)
d.digits[e] = d.digits[e] >>> a | (d.digits[f] & Q[a]) << c;
d.digits[d.digits.length - 1] >>>= a;
d.isNeg = b.isNeg;
return d
}
function C(a, c) {
var b = new h;
p(a.digits, 0, b.digits, c, b.digits.length - c);
return b
}
function x(a, c) {
var b = new h;
p(a.digits, c, b.digits, 0, b.digits.length - c);
return b
}
function D(a, c) {
var b = new h;
p(a.digits, 0, b.digits, 0, c);
return b
}
function M(a, c) {
if (a.isNeg != c.isNeg)
return 1 - 2 * Number(a.isNeg);
for (var b = a.digits.length - 1; 0 <= b; --b)
if (a.digits[b] != c.digits[b])
return a.isNeg ? 1 - 2 * Number(a.digits[b] > c.digits[b]) : 1 - 2 * Number(a.digits[b] < c.digits[b]);
return 0
}
function F(a) {
this.modulus = u(a);
this.k = n(this.modulus) + 1;
a = new h;
a.digits[2 * this.k] = 1;
var c = this.modulus
, b = v(a)
, d = v(c)
, e = c.isNeg;
if (b < d)
if (a.isNeg) {
var f = u(E);
f.isNeg = !c.isNeg;
a.isNeg = !1;
c.isNeg = !1;
var g = l(c, a);
a.isNeg = !0;
c.isNeg = e
} else
f = new h,
g = u(a);
else {
f = new h;
g = a;
for (var q = Math.ceil(d / 16) - 1, k = 0; 32768 > c.digits[q]; )
c = y(c, 1),
++k,
++d,
q = Math.ceil(d / 16) - 1;
g = y(g, k);
b = Math.ceil((b + k) / 16) - 1;
for (d = C(c, b - q); -1 != M(g, d); )
++f.digits[b - q],
g = l(g, d);
for (; b > q; --b) {
d = b >= g.digits.length ? 0 : g.digits[b];
var p = b - 1 >= g.digits.length ? 0 : g.digits[b - 1]
, t = b - 2 >= g.digits.length ? 0 : g.digits[b - 2]
, B = q >= c.digits.length ? 0 : c.digits[q]
, z = q - 1 >= c.digits.length ? 0 : c.digits[q - 1];
f.digits[b - q - 1] = d == B ? 65535 : Math.floor((65536 * d + p) / B);
for (var A = f.digits[b - q - 1] * (65536 * B + z), x = 4294967296 * d + (65536 * p + t); A > x; )
--f.digits[b - q - 1],
A = f.digits[b - q - 1] * (65536 * B | z),
x = 4294967296 * d + (65536 * p + t);
t = d = C(c, b - q - 1);
B = f.digits[b - q - 1];
result = new h;
p = n(t);
for (z = A = 0; z <= p; ++z)
A = result.digits[z] + t.digits[z] * B + A,
result.digits[z] = A & 65535,
A >>>= 16;
result.digits[1 + p] = A;
g = l(g, result);
g.isNeg && (g = w(g, d),
--f.digits[b - q - 1])
}
g = L(g, k);
f.isNeg = a.isNeg != e;
a.isNeg && (f = e ? w(f, E) : l(f, E),
c = L(c, k),
g = l(c, g));
0 == g.digits[0] && 0 == n(g) && (g.isNeg = !1)
}
a = [f, g];
this.mu = a[0];
this.bkplus1 = new h;
this.bkplus1.digits[this.k + 1] = 1;
this.modulo = H;
this.multiplyMod = I;
this.powMod = J
}
function H(a) {
var b = x(a, this.k - 1);
b = t(b, this.mu);
b = x(b, this.k + 1);
a = D(a, this.k + 1);
b = t(b, this.modulus);
b = D(b, this.k + 1);
a = l(a, b);
a.isNeg && (a = w(a, this.bkplus1));
for (b = 0 <= M(a, this.modulus); b; )
a = l(a, this.modulus),
b = 0 <= M(a, this.modulus);
return a
}
function I(a, c) {
a = t(a, c);
return this.modulo(a)
}
function J(a, c) {
var b = new h;
for (b.digits[0] = 1; ; ) {
0 != (c.digits[0] & 1) && (b = this.multiplyMod(b, a));
c = L(c, 1);
if (0 == c.digits[0] && 0 == n(c))
break;
a = this.multiplyMod(a, a)
}
return b
}
function K(a) {
this.e = k("10001");
this.d = k("");
this.m = k(a);
this.chunkSize = 128;
this.radix = 16;
this.barrett = new F(this.m)
}
var N, G, E;
e(20);
(function(a) {
var b = new h;
b.isNeg = 0 > a;
a = Math.abs(a);
for (var f = 0; 0 < a; )
b.digits[f++] = a & 65535,
a >>= 16;
return b
}
)(1E15);
var P = [0, 32768, 49152, 57344, 61440, 63488, 64512, 65024, 65280, 65408, 65472, 65504, 65520, 65528, 65532, 65534, 65535]
, Q = [0, 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767, 65535];
e(131);
return function(a) {
var b = [], e = a.length, d, m = "", l = new K(f);
e > l.chunkSize - 11 && (e = l.chunkSize - 11);
var g = 0;
for (d = e - 1; g < e; )
b[d] = a.charCodeAt(g),
g++,
d--;
for (d = l.chunkSize - e % l.chunkSize; 0 < d; ) {
for (a = Math.floor(256 * Math.random()); !a; )
a = Math.floor(256 * Math.random());
b[g] = a;
g++;
d--
}
b[e] = 0;
b[l.chunkSize - 2] = 2;
b[l.chunkSize - 1] = 0;
e = b.length;
for (g = 0; g < e; g += l.chunkSize) {
var q = new h;
d = 0;
for (a = g; a < g + l.chunkSize; ++d)
q.digits[d] = b[a++],
q.digits[d] += b[a++] << 8;
d = l.barrett.powMod(q, l.e);
q = "";
for (a = n(d); -1 < a; --a) {
var k = d.digits[a];
var p = String.fromCharCode(k & 255);
k = String.fromCharCode(k >>> 8 & 255) + p;
q += k
}
d = q;
m += d
}
return m
}(a)
}
function get_pwd(password, w, l, f) {
var e = K(w + "\t" + l + "\t" + password, f);
return btoa(e)
}