On The Deniability of Ma et al.'s Deniable Authenticated Key Agreement Protocol

A deniable authentication protocol enables the protocol participants to authenticate their respective peers, while able to deny their participation after the protocol execution. In 2007, Ma et al. have proposed a chameleon-based deniable authenticated key agreement protocol. However, we discover that this scheme is in fact undeniable due to some flaws in it’ s protocol design. In this paper, we prove the opposite of their claims and discuss the undeniability of the scheme in detail.