Errors in Computational Complexity Proofs for Protocols

Kim-Kwang Raymond Choo, Colin Boyd, Yvonne Hitchcock

Abstract: Proofs are invaluable tools in assuring protocol implementers about the security properties of protocols. However, several instances of undetected flaws in the proofs of protocols (resulting in flawed protocols) undermine the credibility of provably-secure protocols. In this work, we examine several protocols with claimed proofs of security by Boyd & González Nieto (2003), Jakobsson & Pointcheval (2001), and Wong & Chan (2001), and an authenticator by Bellare, Canetti, & Krawczyk (1998). Using these protocols as case studies, we reveal previously unpublished flaws in these protocols and their proofs. We hope our analysis will enable similar mistakes to be avoided in the future.