© 2017, Springer International Publishing AG. Deniable authentication allows the participants to deny an authentication process as there is no any evidence that it ever took place. It is quite suitable for the privacy-preserving scenario. Combining with the ring signature property, the deniable authentication can reach the source hiding. In other words, the receiver is only convinced that a member in a group is authenticating a message without knowing which one. It is also deniable, that is the receiver cannot convince anyone else that this message was indeed authenticated. We present a deniable ring authentication based on the projective hash function. With this building block the underlying (encryption) scheme is not required to be CCA secure, which results in a more realistic deniable authentication protocol.