DSH: Deniable secret handshake framework

Secret handshake is a useful primitive that allows a group of authorized users to establish a shared secret key and authenticate each other anonymously. It naturally provides a certain degree of user privacy and deniability which are also desirable for some private conversations that require secure key establishment. The inherent user privacy enables a private conversation between authorized users without revealing their real identities. While deniability allows authorized users to later deny their participating in conversations. However, deniability of secret handshakes lacks a comprehensive treatment in the literature. In this paper, we investigate the deniability of existing secret handshakes. We propose the first generic framework that converts any secret handshake protocols into fully deniable ones. In particular, we define two formal security models, including session key security and deniability for our proposed framework.