本文主要是介绍爬虫逆向实战(36)-某建设监管平台(RSA，魔改)，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
一、数据接口分析
主页地址：某建设监管平台
1、抓包
通过抓包可以发现网站首先是请求了一个/prod-api/mohurd-pub/vcode/genVcode的接口，用于获取滑块验证码的图片
滑块验证之后，请求了/prod-api/mohurd-pub/dataServ/findBaseEntDpPage这个接口，来获取数据
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，这两个接口都是只有一个params的加密参数
- 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包含异步，所以无法正确找到加密位置
2、搜索关键字
通过搜索关键字，发现可以搜出来很多位置，无法准确定位到加密位置
3、Hook
因为请求参数中只有一个params参数，所以网站大概率会使用JSON.stringify方法将明文数据转json之后再加密。
通过hook，我们可以找到加密位置
同时，可以发现params是进行了双重加密，首先使用W_e().encrypt进行了一次加密（此处有点类似于AES或DES加密，但是通过测试，发现加密结果不一致，所以可能是魔改加密算法），然后将加密结果再使用X_e进行二次加密（此处是标准RSA加密）。
三、扣js代码
将W_e().encrypt方法扣出，缺啥补啥即可，X_e方法可以扣网站代码，也可以直接使用标准模块。
注：
此网站的滑块验证码，仅需将缺口距离在第二次数据接口请求时带上即可
源代码：
const JSEncrypt = require('jsencrypt');
const G_e = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC29miF1Wp9XlhCECo+FYpCHad1ipEMgXf4IdgYjMIQwczzo9GXdcZ4eeV+9lkh6+aTqzzU843rdkMt0vrSnujU+GOuDPLfa5LZ6SfanAoysi6xxTX02Xizb3k+Z1USIzm9QAwE+SR1AQ78rGTRFHWFu7OGPkVNeF+vrX3inQTiawIDAQAB";function Jbe(e) {var t = n7(e), n = t[0], o = t[1];return (n + o) * 3 / 4 - o
}function exe(e) {var t, n = n7(e), o = n[0], r = n[1], s = new Xbe(Qbe(e, o, r)), a = 0, l = r > 0 ? o - 4 : o, i;for (i = 0; i < l; i += 4)t = oo[e.charCodeAt(i)] << 18 | oo[e.charCodeAt(i + 1)] << 12 | oo[e.charCodeAt(i + 2)] << 6 | oo[e.charCodeAt(i + 3)],s[a++] = t >> 16 & 255,s[a++] = t >> 8 & 255,s[a++] = t & 255;return r === 2 && (t = oo[e.charCodeAt(i)] << 2 | oo[e.charCodeAt(i + 1)] >> 4,s[a++] = t & 255),r === 1 && (t = oo[e.charCodeAt(i)] << 10 | oo[e.charCodeAt(i + 1)] << 4 | oo[e.charCodeAt(i + 2)] >> 2,s[a++] = t >> 8 & 255,s[a++] = t & 255),s
}
function txe(e) {return Vo[e >> 18 & 63] + Vo[e >> 12 & 63] + Vo[e >> 6 & 63] + Vo[e & 63]
}
function nxe(e, t, n) {for (var o, r = [], s = t; s < n; s += 3)o = (e[s] << 16 & 16711680) + (e[s + 1] << 8 & 65280) + (e[s + 2] & 255),r.push(txe(o));return r.join("")
}
function oxe(e) {for (var t, n = e.length, o = n % 3, r = [], s = 16383, a = 0, l = n - o; a < l; a += s)r.push(nxe(e, a, a + s > l ? l : a + s));return o === 1 ? (t = e[n - 1],r.push(Vo[t >> 2] + Vo[t << 4 & 63] + "==")) : o === 2 && (t = (e[n - 2] << 8) + e[n - 1],r.push(Vo[t >> 10] + Vo[t >> 4 & 63] + Vo[t << 2 & 63] + "=")),r.join("")
}var jc = {};
jc.byteLength = Jbe;
jc.toByteArray = exe;
jc.fromByteArray = oxe;
const O6 = jc;
var Vo = [], oo = [], Xbe = typeof Uint8Array != "undefined" ? Uint8Array : Array, Lu = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
for (var js = 0, Zbe = Lu.length; js < Zbe; ++js)Vo[js] = Lu[js],oo[Lu.charCodeAt(js)] = js;
class V_e {static stringToArrayBufferInUtf8(t) {const n = typeof window == "undefined" ? yd.TextEncoder : window.TextEncoder;return new n().encode(t)}static utf8ArrayBufferToString(t) {const n = typeof window == "undefined" ? yd.TextDecoder : window.TextDecoder;return new n("utf-8").decode(t)}static arrayBufferToBase64(t) {return O6.fromByteArray(t)}static base64ToArrayBuffer(t) {return O6.toByteArray(t)}
}const Sr = V_e, to = 16, Di = Uint8Array.from([214, 144, 233, 254, 204, 225, 61, 183, 22, 182, 20, 194, 40, 251, 44, 5, 43, 103, 154, 118, 42, 190, 4, 195, 170, 68, 19, 38, 73, 134, 6, 153, 156, 66, 80, 244, 145, 239, 152, 122, 51, 84, 11, 67, 237, 207, 172, 98, 228, 179, 28, 169, 201, 8, 232, 149, 128, 223, 148, 250, 117, 143, 63, 166, 71, 7, 167, 252, 243, 115, 23, 186, 131, 89, 60, 25, 230, 133, 79, 168, 104, 107, 129, 178, 113, 100, 218, 139, 248, 235, 15, 75, 112, 86, 157, 53, 30, 36, 14, 94, 99, 88, 209, 162, 37, 34, 124, 59, 1, 33, 120, 135, 212, 0, 70, 87, 159, 211, 39, 82, 76, 54, 2, 231, 160, 196, 200, 158, 234, 191, 138, 210, 64, 199, 56, 181, 163, 247, 242, 206, 249, 97, 21, 161, 224, 174, 93, 164, 155, 52, 26, 85, 173, 147, 50, 48, 245, 140, 177, 227, 29, 246, 226, 46, 130, 102, 202, 96, 192, 41, 35, 171, 13, 83, 78, 111, 213, 219, 55, 69, 222, 253, 142, 47, 3, 255, 106, 114, 109, 108, 91, 81, 141, 27, 175, 146, 187, 221, 188, 127, 17, 217, 92, 65, 31, 16, 90, 216, 10, 193, 49, 136, 165, 205, 123, 189, 45, 116, 208, 18, 184, 229, 180, 176, 137, 105, 151, 74, 12, 150, 119, 126, 101, 185, 241, 9, 197, 110, 198, 132, 24, 240, 125, 236, 58, 220, 77, 32, 121, 238, 95, 62, 215, 203, 57, 72]), L_e = Uint32Array.from([462357, 472066609, 943670861, 1415275113, 1886879365, 2358483617, 2830087869, 3301692121, 3773296373, 4228057617, 404694573, 876298825, 1347903077, 1819507329, 2291111581, 2762715833, 3234320085, 3705924337, 4177462797, 337322537, 808926789, 1280531041, 1752135293, 2223739545, 2695343797, 3166948049, 3638552301, 4110090761, 269950501, 741554753, 1213159005, 1684763257]), Oi = Uint32Array.from([2746333894, 1453994832, 1736282519, 2993693404]);class R_e {constructor(t) {let n = Sr.stringToArrayBufferInUtf8(t.key);if (n.length !== 16)throw new Error("key should be a 16 bytes string");this.key = n;let o = new Uint8Array(0);if (t.iv !== void 0 && t.iv !== null && (o = Sr.stringToArrayBufferInUtf8(t.iv),o.length !== 16))throw new Error("iv should be a 16 bytes string");this.iv = o,this.mode = "cbc",["cbc", "ecb"].indexOf(t.mode) >= 0 && (this.mode = t.mode),this.cipherType = "base64",["base64", "text"].indexOf(t.outType) >= 0 && (this.cipherType = t.outType),this.encryptRoundKeys = new Uint32Array(32),this.spawnEncryptRoundKeys(),this.decryptRoundKeys = Uint32Array.from(this.encryptRoundKeys),this.decryptRoundKeys.reverse()}doBlockCrypt(t, n) {let o = new Uint32Array(36);o.set(t, 0);for (let s = 0; s < 32; s++)o[s + 4] = o[s] ^ this.tTransform1(o[s + 1] ^ o[s + 2] ^ o[s + 3] ^ n[s]);let r = new Uint32Array(4);return r[0] = o[35],r[1] = o[34],r[2] = o[33],r[3] = o[32],r}spawnEncryptRoundKeys() {let t = new Uint32Array(4);t[0] = this.key[0] << 24 | this.key[1] << 16 | this.key[2] << 8 | this.key[3],t[1] = this.key[4] << 24 | this.key[5] << 16 | this.key[6] << 8 | this.key[7],t[2] = this.key[8] << 24 | this.key[9] << 16 | this.key[10] << 8 | this.key[11],t[3] = this.key[12] << 24 | this.key[13] << 16 | this.key[14] << 8 | this.key[15];let n = new Uint32Array(36);n[0] = t[0] ^ Oi[0],n[1] = t[1] ^ Oi[1],n[2] = t[2] ^ Oi[2],n[3] = t[3] ^ Oi[3];for (let o = 0; o < 32; o++)n[o + 4] = n[o] ^ this.tTransform2(n[o + 1] ^ n[o + 2] ^ n[o + 3] ^ L_e[o]),this.encryptRoundKeys[o] = n[o + 4]}rotateLeft(t, n) {return t << n | t >>> 32 - n}linearTransform1(t) {return t ^ this.rotateLeft(t, 2) ^ this.rotateLeft(t, 10) ^ this.rotateLeft(t, 18) ^ this.rotateLeft(t, 24)}linearTransform2(t) {return t ^ this.rotateLeft(t, 13) ^ this.rotateLeft(t, 23)}tauTransform(t) {return Di[t >>> 24 & 255] << 24 | Di[t >>> 16 & 255] << 16 | Di[t >>> 8 & 255] << 8 | Di[t & 255]}tTransform1(t) {let n = this.tauTransform(t);return this.linearTransform1(n)}tTransform2(t) {let n = this.tauTransform(t);return this.linearTransform2(n)}padding(t) {if (t === null)return null;let n = to - t.length % to, o = new Uint8Array(t.length + n);return o.set(t, 0),o.fill(n, t.length),o}dePadding(t) {if (t === null)return null;let n = t[t.length - 1];return t.slice(0, t.length - n)}uint8ToUint32Block(t, n=0) {let o = new Uint32Array(4);return o[0] = t[n] << 24 | t[n + 1] << 16 | t[n + 2] << 8 | t[n + 3],o[1] = t[n + 4] << 24 | t[n + 5] << 16 | t[n + 6] << 8 | t[n + 7],o[2] = t[n + 8] << 24 | t[n + 9] << 16 | t[n + 10] << 8 | t[n + 11],o[3] = t[n + 12] << 24 | t[n + 13] << 16 | t[n + 14] << 8 | t[n + 15],o}encrypt(t) {let n = Sr.stringToArrayBufferInUtf8(t), o = this.padding(n), r = o.length / to, s = new Uint8Array(o.length);if (this.mode === "cbc") {if (this.iv === null || this.iv.length !== 16)throw new Error("iv error");let a = this.uint8ToUint32Block(this.iv);for (let l = 0; l < r; l++) {let i = l * to, c = this.uint8ToUint32Block(o, i);a[0] = a[0] ^ c[0],a[1] = a[1] ^ c[1],a[2] = a[2] ^ c[2],a[3] = a[3] ^ c[3];let u = this.doBlockCrypt(a, this.encryptRoundKeys);a = u;for (let f = 0; f < to; f++)s[i + f] = u[parseInt(f / 4)] >> (3 - f) % 4 * 8 & 255}} elsefor (let a = 0; a < r; a++) {let l = a * to, i = this.uint8ToUint32Block(o, l), c = this.doBlockCrypt(i, this.encryptRoundKeys);for (let u = 0; u < to; u++)s[l + u] = c[parseInt(u / 4)] >> (3 - u) % 4 * 8 & 255}return this.cipherType === "base64" ? Sr.arrayBufferToBase64(s) : Sr.utf8ArrayBufferToString(s)}decrypt(t) {let n = new Uint8Array;this.cipherType === "base64" ? n = Sr.base64ToArrayBuffer(t) : n = Sr.stringToArrayBufferInUtf8(t);let o = n.length / to, r = new Uint8Array(n.length);if (this.mode === "cbc") {if (this.iv === null || this.iv.length !== 16)throw new Error("iv error");let a = this.uint8ToUint32Block(this.iv);for (let l = 0; l < o; l++) {let i = l * to, c = this.uint8ToUint32Block(n, i), u = this.doBlockCrypt(c, this.decryptRoundKeys), f = new Uint32Array(4);f[0] = a[0] ^ u[0],f[1] = a[1] ^ u[1],f[2] = a[2] ^ u[2],f[3] = a[3] ^ u[3],a = c;for (let d = 0; d < to; d++)r[i + d] = f[parseInt(d / 4)] >> (3 - d) % 4 * 8 & 255}} elsefor (let a = 0; a < o; a++) {let l = a * to, i = this.uint8ToUint32Block(n, l), c = this.doBlockCrypt(i, this.decryptRoundKeys);for (let u = 0; u < to; u++)r[l + u] = c[parseInt(u / 4)] >> (3 - u) % 4 * 8 & 255}let s = this.dePadding(r);return Sr.utf8ArrayBufferToString(s)}
}
var j_e = {sm4: R_e
}
function W_e() {const t = {};t.key = "B6*40.2_C9#e4$E3",t['mode'] = 'ecb',t.cipherType = "base64";const n = t, o = j_e['sm4'];return new o(n)
}function get_params(data) {e = W_e().encrypt(JSON.stringify(data))var encrypt = new JSEncrypt();encrypt.setPublicKey(G_e);const o = 117, r = Math['ceil'](e['length'] / o);let s = [];for (let a = 0; a < r; a++) {const l = e.slice(a * o, (a + 1) * o), i = encrypt.encrypt(l);s.push(i)}return s
}
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