class type auth_session =Anobject
..end
auth_session
object is normally created for every client instance.
It contains the current state of authentication. The methods are only
interesting for implementors of authentication methods.
This class type might be revised in the future to allow asynchronous
authentication (authentication often uses some network service).
method next_credentials : t -> string * string * string * string
method server_rejects : Rpc.server_error -> unit
method server_accepts : string -> string -> unit
Rpc_server Rpc_invalid_resp
to indicate
that the returned verifier is wrong.