Ring signatures are a powerful primitive that allows a member to sign on behalf of a group, without revealing their identity. Recently, ring signatures have received additional attention as an ingredient for post-quantum deniable authenticated key exchange, e.g., for a post-quantum version of the Signal protocol, employed by virtually all end-to-end-encrypted messenger services. In this talk, I will review the state of the art in deniable authentication mechanisms for post-quantum instant messaging. I will then present some recent results on post-quantum security proofs for two generic ring signature constructions, the AOS framework and a construction paradigm based on ring trapdoors.