universal-github-app-jwt

Calculate GitHub App bearer tokens for Node & modern browsers

Usage no npm install needed!

<script type="module">
  import universalGithubAppJwt from 'https://cdn.skypack.dev/universal-github-app-jwt';
</script>

README

universal-github-app-jwt

Calculate GitHub App bearer tokens for Node & modern browsers

@latest Build status Greenkeeper

⚠ The private keys provide by GitHub are in PKCS#1 format, but the WebCrypto API only supports PKCS#8. You can see the difference in the first line, PKCS#1 format starts with -----BEGIN RSA PRIVATE KEY----- while PKCS#8 starts with -----BEGIN PRIVATE KEY-----. You can convert one format to the other using oppenssl:

openssl pkcs8 -topk8 -inform PEM -outform PEM -nocrypt -in private-key.pem -out private-key-pkcs8.key

It's also possible to convert the formats with JavaScript, e.g. using node-rsa, but it turns a 4kb to a 200kb+ built. I'm looking for help to create a minimal PKCS#1 to PKCS#8 convert library that I can recommend people to use before passing the private key to githubAppJwt. Please create an issue if you'd like to help.

The way it works with node-rsa is this

const PRIVATE_KEY = `-----BEGIN RSA PRIVATE KEY-----
...
-----END RSA PRIVATE KEY-----`;

const key = new NodeRSA(PRIVATE_KEY);
const privateKeyPkcs8 = key.exportKey("pkcs8-private-pem");

// privateKeyPkcs8 is now
// -----BEGIN PRIVATE KEY-----
// ...
// -----END PRIVATE KEY-----

When using a node, a conversion is not necessary, the implementation is agnostic to either format.

Usage

Browsers

Load universal-github-app-jwt directly from cdn.pika.dev

<script type="module">
  import { githubAppJwt } from "https://cdn.pika.dev/universal-github-app-jwt";
</script>
Node

Install with npm install universal-github-app-jwt

const { githubAppJwt } = require("universal-github-app-jwt");
// or: import { githubAppJwt } from "universal-github-app-jwt";

(async () => {
  const { token, appId, expiration } = await githubAppJwt({
    id: APP_ID,
    privateKey: PRIVATE_KEY
  });
})();

The retrieved token can now be used in Authorization request header, e.g. with @octokit/request:

request("GET /app", {
  headers: {
    authorization: `bearer ${token}`
  }
});

For a complete implementation of GitHub App authentication strategies, see @octokit/auth-app.js.

githubAppJwt(options)

name type description
options.id number Required. Find App ID on the app’s about page in settings.
options.privateKey string Required. Content of the *.pem file you downloaded from the app’s about page. You can generate a new private key if needed. Make sure to preserve the line breaks.

githubAppJwt(options) resolves with an object with the following keys

name type description
token string The JSON Web Token (JWT) to authenticate as the app.
appId number The GitHub App database ID passed in options.id.
expiration number Timestamp as UNIX epoch, e.g. 1530922170. A Date object can be created using new Date(authentication.expiration).

License

MIT