Cryptanalysis of an improved client-to-client Password-Authenticated Key Exchange (C2C-PAKE) scheme

Abstract

Password-Authenticated Key Establishment (PAKE) protocols allow two parties, to share common secret keys in an authentic manner based on an easily memorizable password. At ICCSA 2004, an improved PAKE protocol between two clients of different realms was proposed that was claimed to be secure against attacks including the replay attack. In this paper, we cryptanalyze this protocol by showing two replay attacks that allow an attacker to falsely share a secret key with a legal client. © Springer-Verlag Berlin Heidelberg 2005.