Is there a way to use user-defined channel credentials?

[Yunhao Bai]

Hi gRPC team,

  We are developing some auth mechanism using gRPC in C++, and we should like to have both channel and call level authentication enable in a gRPC server.

  In our scenario of a internal communication, we need to comply to some authentication flow other than SSL-like ones. As far as I know, the metadataAuthenticator used for call level authentication cannot do some negotiation stuff like exchange tokens between client and server. We have to do this in the channel credential. 

So we would want to know if we can have a user-defined channel credential (just like slServerCredentials)? Or we can achieve some thing similar using call level authenticator (sever-client negotiation)?

Thanks,

Cloud