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

1. 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
   
2. 请求头是否加密？
   无
3. 响应是否加密？
   无
4. 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} elser.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} elsef = 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)
}