Reverse engineering cryptopanic.com API response

cryptopanic-decrypt.js

require('dotenv').config();
const CryptoJS = require("crypto-js");
const pako = require('pako');
const fs = require('fs');
const path = require('path');

const ENCRYPTION_KEY = process.env.CRYPTOPANIC_ENCRYPTION_KEY;
const CSRF_TOKEN = process.env.CRYPTOPANIC_CSRF_TOKEN;

function wordToByteArray(t, e) {
    var n = [];
    return (
      e > 0 && n.push(t >>> 24),
      e > 1 && n.push((t >>> 16) & 255),
      e > 2 && n.push((t >>> 8) & 255),
      e > 3 && n.push(255 & t),
      n
    );
  }

function wordArrayToByteArray(t, e) {
    t.hasOwnProperty("sigBytes") &&
      t.hasOwnProperty("words") &&
      ((e = t.sigBytes), (t = t.words));
    for (var n, s = [], i = 0; e > 0; )
      (n = wordToByteArray(t[i], Math.min(4, e))),
        (e -= n.length),
        s.push(n),
        i++;
    return [].concat.apply([], s);
}

function normalizeDictList(t) {
    var e = [];
    return (
      t.l.forEach(function (n) {
        var s = {};
        t.k.forEach(function (t, e) {
          s[t] = n[e];
        }),
          e.push(s);
      }),
      e
    );
  }

// { words, sigBytes }
const key = CryptoJS.enc.Utf8.parse(ENCRYPTION_KEY);

// for posts
const postIvRaw = "news" + CSRF_TOKEN.substring(0, 12);
// for dashboard
const dashboardIvRaw = "newsrnlistrnlist";
const padding = CryptoJS.pad.ZeroPadding;

const postEncrypted = fs.readFileSync(path.join(__dirname, 'input', 'cryptopanic post data'), { encoding: 'utf-8' } );
const dashboardEncrypted = fs.readFileSync(path.join(__dirname, 'input', 'cryptopanic dashboard data'), { encoding: 'utf-8' });

const dataTypeMapping = {
    post: {
        iv: CryptoJS.enc.Utf8.parse(postIvRaw),
        encrypted: postEncrypted
    },
    dashboard: {
        iv: CryptoJS.enc.Utf8.parse(dashboardIvRaw),
        encrypted: dashboardEncrypted
    }
}

function decrypt(encrypted, key, iv, padding, dataType) {
    // { words, sigBytes }
    const decrypted = CryptoJS.AES.decrypt(encrypted, key, {
        iv,
        padding,
    });

    const byteArray = wordArrayToByteArray(decrypted);

    try {
        const inflated = pako.inflate(byteArray, { to: 'string' });
        const inflatedJson = JSON.parse(inflated);

        fs.writeFileSync(path.join(__dirname, 'decrypted', `${dataType}-inflatedRaw.json`), JSON.stringify(inflatedJson, undefined, 2));

        const normalized = normalizeDictList(inflatedJson);

        fs.writeFileSync(path.join(__dirname, 'decrypted', `${dataType}-normalized.json`), JSON.stringify(normalized, undefined, 2));

        return normalized;
    } catch(e) {
        console.log(e);
    }
}

// node decrypt.js
// dataType = 'post', 'dashboard'
if (require.main === module) {
    let [_, __, dataType] = process.argv;
    dataType = dataType ? dataType : 'post';

    const decrypted = decrypt(dataTypeMapping[dataType].encrypted, key, dataTypeMapping[dataType].iv, padding, dataType);
    console.log(decrypted);
}