Hi. 

We run all our integrations via a custom middleware. Pega will receive as service provider, next to the payload, also an access token (JWT) which must be validated against an external auth provider. 

I have prepared a token profile (JWT) for processing the signature validation via a keystore (configured JWK with external keystore URL). My idea is now to configure a authentication service of type custom on the service package which will trigger the processing of the configured token profile. But i cannot find a OOTB authentication service of type custom (or any examples) to trigger this. Also in the engine API documentation I have not found any hints how this could be triggered in a authentication service of type custom. 

Have somone implemented this or can give me a hint, how this can be established?

Regards, Matthias