1. A method of concealing authentication credentials of an entity when routing messages in a message routing service, the method including: receiving, at a message routing service, an authentication request to authenticate an entity with the message routing service; generating at the message routing service an authentication token for the entity based on entity's authentication credentials, the authentication token indicating authentication of the entity to the message routing service; sending at least one provisioning message to an application service provider using the message routing service, wherein the provisioning message includes the authentication token, rather than the entity's authentication credentials that remain concealed, and provisions the entity with the application service provider; and receiving, at the message routing service, a message from the application service provider indicating authentication of the entity by the application service provider responsive to the authentication token generated by the message routing service.