WordPress.com features (signing in with a WordPress.com account, the Reader, Stats, etc.) are authenticated with OAuth2, which requires a client ID and a client secret. These details are used to authenticate your application and verify that the API calls being made are valid. The credentials in the repository are placeholders, so you need to register your own application and point the app at it.

1. Create an application with the WordPress.com applications manager. Select "Native client" for the application type.

2. Add both of the following to "Redirect URLs", one per line:

   wordpress://wpcom-authorize
   jetpack://wpcom-authorize
   

   Authentication takes place in the browser and returns to the app through a URL scheme, which differs per app: wordpress for WordPress and jetpack for Jetpack. WordPress.com only redirects to a URL that exactly matches a registered one, so register both if you intend to run both apps. The "Website URL" and "Javascript Origins" fields are required by the form but aren't used by the apps. Just use "https://localhost".

3. From the root of the repository, copy the example configuration file. secrets.properties is ignored by Git, so your credentials stay out of version control:

   $ cp secrets.properties-example secrets.properties
   

4. In secrets.properties, uncomment wp.oauth.app_id and wp.oauth.app_secret and set them to the "Client ID" and "Client Secret" of the application you created.

5. Rebuild the app, then choose "Log in or sign up with WordPress.com" on the app start up screen.

Note that authenticating to WordPress.com via Google is not supported in development builds of the app, only in the official release. See the Google Configuration section of the README for details.

Read more about OAuth2 and the WordPress.com REST endpoint.