A Node.js script to decrypt xBrowserSync sync data.

index.js

const crypto = require('crypto');
const lzutf8 = require('lzutf8');
const util = require('util');
const pbkdf2 = util.promisify(crypto.pbkdf2);

async function getPasswordHash(password, syncId) {
  // Generate pbkdf2 key and return as base64 string
  const encoder = new util.TextEncoder('utf-8');
  const keyData = encoder.encode(password);
  const salt = encoder.encode(syncId);
  const derivedKey = await pbkdf2(keyData, salt, 250000, 32, 'sha256');
  const keyString = derivedKey.toString('base64');
  return keyString;
}

async function decryptData(key, encryptedBookmarks) {
  // Get the required data arrays for decryption
  const keyData = Uint8Array.from(Buffer.from(key, 'base64'));
  const encrypted_bytes = Uint8Array.from(Buffer.from(encryptedBookmarks, 'base64'));
  const iv = encrypted_bytes.slice(0, 16);
  const tag = encrypted_bytes.slice(-16);
  const enc = encrypted_bytes.slice(16, encrypted_bytes.length - 16);
  
  // Run decryption and return buffer
  const decipher = crypto.createDecipheriv('aes-256-gcm', keyData, iv, { authTagLength: 16 });
  decipher.setAuthTag(tag);
  const decrypted = Buffer.concat([decipher.update(enc), decipher.final()]);
  return decrypted;
}

(async () => {
  // The raw entered password (50 characters in my case)
  const plainTextPassword = 'asd';

  // The sync ID extracted from the xbrowsersync UI (32 characters)
  const syncId = 'bdf7b0a552c347cc8479a7b287a43c00';

  // Encrypted bookmarks, extracted for testing from Chrome
  const encryptedBookmarks = `dsAxxN4gQHvsr/5BPF8F1G84oxlTroAbDX++ha8JgHJgjE8iXvQH2+7t3daG3r2WPsmLRS/KWdc/FwntiAYqSZIzQQQn6VcKYFVCdA/ZeSjZhxYh3SnG8i/FA6zgI/hBWvbk4W/xgW14tvA1lNGHAYFU6ZAXhOlR`;
  
  // Generate the password hash
  const key = await getPasswordHash(plainTextPassword, syncId);
  
  // Decrypt the encrypted data using password hash
  const decryptedData = await decryptData(key, encryptedBookmarks);

  // Decompress the decrypted data to it's original json and beautify
  const decryptedJson = lzutf8.decompress(decryptedData);
  const beautifiedJson = JSON.stringify(JSON.parse(decryptedJson), null, 2);
  console.log(beautifiedJson);
})();

package.json

{
  "name": "xbrowsersync-node-decryption",
  "version": "1.0.0",
  "description": "A Node.js script to decrypt xBrowserSync sync data.",
  "main": "index.js",
  "dependencies": {
    "lzutf8": "^0.5.5"
  }
}