Cryptoanalysis and Improvements of Cross-Realm C2C-PAKE Protocol

Most existing cross realm client to client password authenticated key exchange (C2C-PAKE) protocols can not resist password compromise impersonation (PCI) attack. This paper gives a method of resisting this attack and proposes an improved cross realm C2C-PAKE protocol based on EC2C-PAKA protocol [Byun et. al, 2007]. The novel protocol can hold all security characteristics of the original protocol and resist PCI attack. Then this paper proves that the improved protocol is forward secrecy under the Diffie Hellman assumption in the random oracle and ideal cipher models. Finally, through evaluating the efficiency and security of the novel protocol, the improved protocol not only has stronger security, but also is more efficient.