okova

Okova is a set of tools (JavaScript library, command-line utility and browser extension) for diagnosing, researching, and pentesting DRM systems used in playable media content.

Okova is still in the early stages of development, so until version 1.0 is released, performance may be unstable and major changes may be made

Features

• Logging details from EME events in DevTools console
• Network-independent interception via browser extension, so it doesn't matter if license request has one-time tokens or a custom request/response body format
• Remote instance to manage sessions via REST API
• Custom CDM client support: create *.wvd or *.prd from raw client files and import them into browser extension
• Runtime agnostic core: works in Node.js, Bun, Deno, browsers and more
• Encrypted Media Extensions API compatibility via requestMediaKeySystemAccess() method

Browser Extension

Installing Chrome extension

Developer Mode needs to be enabled in chrome://extensions/ page

1. Download archive from latest release
2. Go to chrome://extensions/ page
3. Ensure Developer Mode enabled and then drag and drop downloaded zip file to this page

Read Google's guide

Installing Firefox extension

1. Download archive from latest release
2. Go to about:debugging#/runtime/this-firefox page
3. Click Load Temporary Add-on button and choose downloaded zip file

Temporary add-on is not persistent and will be removed after browser restart

Read Mozilla's guide

Command-line tool

Installation

Command-line tool installation requires pre-installed JavaScript runtime (e.g. Node.js).

npm install -g okova

Usage

See help for all possible arguments and options: okova --help

Convert DRM client files ./drm-files/device_client_id_blob and ./drm-files/device_private_key to single WVD file:

okova client pack ./drm-files ./unknown_android-sdk-built-for-x86.wvd

Client packed: /Users/.../unknown_android-sdk-built-for-x86.wvd

Show DRM client info:

okova client info ./unknown_android-sdk-built-for-x86.wvd

application_name: org.chromium.webview_shell
company_name: unknown
model_name: Android SDK built for x86
architecture_name: x86
device_name: generic_x86
product_name: sdk_phone_x86
build_info: Android/sdk_phone_x86/generic_x86:10/RSR1.410600.002.B3/1792159:userdebug/dev-keys
widevine_cdm_version: 16.0.0
oem_crypto_security_patch_level: 0
oem_crypto_build_information: OEMCrypto Level3 Code 8162 May  9 2018 14:01:12

JavaScript library

Library installation requires pre-installed JavaScript runtime (e.g. Node.js).

Installation

npm install okova

Usage

See examples for more.

Obtain a Widevine license for Bitmovin's video:

import { readFile } from 'node:fs/promises';
import { fromBase64, Widevine, requestMediaKeySystemAccess } from 'okova';

async function main() {
  // Prepare init data
  const initDataType = 'cenc'; // Encryption scheme
  const initData = fromBase64(
    'AAAAW3Bzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAADsIARIQ62dqu8s0Xpa7z2FmMPGj2hoNd2lkZXZpbmVfdGVzdCIQZmtqM2xqYVNkZmFsa3IzaioCSEQyAA==',
  ).toBuffer(); // PSSH

  // Load device/client
  const client = await Widevine.Client.from({ wvd: await readFile('client.wvd') });

  const cdm = new Widevine({ client });

  // Create session
  const keySystemAccess = requestMediaKeySystemAccess(cdm.keySystem, []);
  const mediaKeys = await keySystemAccess.createMediaKeys({ cdm });
  const session = mediaKeys.createSession();

  // Get license challenge
  session.generateRequest(initDataType, initData);
  const challenge = await session.waitForLicenseRequest();

  // Send license request
  const licenseUrl = 'https://cwip-shaka-proxy.appspot.com/no_auth';
  const response = await fetch(licenseUrl, { body: challenge, method: 'POST' })
    .then((r) => r.arrayBuffer())
    .then((buffer) => new Uint8Array(buffer));

  // Update session with license response
  await session.update(response);

  // Print keys
  const keys = await session.waitForKeyStatusesChange();
  for (const key of keys) {
    console.log(`${key.keyId}:${key.key}`);
  }

  await session.close(); // Close session to delete of any license(s) and key(s) that have not been explicitly stored.
  await session.remove(); // Destroy the license(s) and/or key(s) associated with the session whether they are in memory, persistent store or both.
}

Disclaimer

1. This project does not condone piracy or any action against the terms of the DRM systems.
2. All efforts in this project have been the result of Reverse-Engineering, Publicly available research, and Trial & Error.
3. Do not use this program to decrypt or access any content for which you do not have the legal rights or explicit permission.
4. Unauthorized decryption or distribution of copyrighted materials is a violation of applicable laws and intellectual property rights.
5. This tool must not be used for any illegal activities, including but not limited to piracy, circumventing digital rights management (DRM), or unauthorized access to protected content.
6. The developers, contributors, and maintainers of this program are not responsible for any misuse or illegal activities performed using this software.
7. By using this program, you agree to comply with all applicable laws and regulations governing digital rights and copyright protections.