Doorkeeper JWT Assertion

Extending Doorkeeper to support JWT Assertion grant type using a secret or a private key file.

This library is in alpha. Future incompatible changes may be necessary.

Install

Add the gem to the Gemfile

gem 'doorkeeper-jwt_assertion'

Configuration

Inside your doorkeeper configuration file add the one of the fallowing:

Doorkeeper.configure do
	
	jwt_private_key Rails.root.join('config', 'keys', 'private.key')

	jwt_secret 'notasecret'

	# Optional
	jwt_use_issuer_as_client_id true
end

This will automatically push assertion into the Doorkeeper's grant_types configuration attribute.

When jwt_use_issuer_as_client_id is set to false then the client_id MUST be available from the parameters. By default it will extract the 'iss' and use it as the client_id to retrieve the oauth application.

Use the resource_owner_authenticator in the configuration to identify the owner based on the JWT claim values. This values can be accessible from jwt. If the client request a token with an invalid assertion, or an expired JWT claim, an :invalid_grant error response will be generated before retrieving the resource_owner.

Doorkeeper.configure do
	
	resource_owner_authenticator do

		if jwt
			jwt['prn'].present? and User.find_by_email(jwt['prn'])
		end

	end

end

Client Usage

Generate an assertion request token using a private key file or a secret:

client = OAuth2::Client.new('client_id', 'client_secret', :site => 'http://my-site.com')

p12 = OpenSSL::PKCS12.new( Rails.root.join('config', 'keys', 'private.p12').open )

params = { :private_key => p12.key,
           :aud => 'audience',
           :prn => 'person', # or :sub => 'subject', not suported on OAuth2 1.0.0 yet.
           :iss => 'client_id',
           :scope => 'scope',
           :exp => Time.now.utc.to_i + 5.minutes }

token = client.assertion.get_token(params)

"[...] refresh tokens are not issued in response to assertion grant requests and access tokens will be issued with a reasonably short lifetime."

• draft-ietf-oauth-assertions-18

TO DO

• Better error handling
• JWT Client Authentication Flow
• Testing