Cryptanalysis of authenticated key exchange 3P-EKE protocol and its enhancement

Key Agreement or key exchange algorithm proposed by Diffie-Hellman in 1976 has suffered from man-in-middle attack. In 2002, Zhu et al. proposed a password authenticated key exchange protocol based on RSA. Later, Yeh et al. has shown that Zhu et al.´s protocol suffers from the undetectable password-guessing attacks and also has given solutions for improvement. Recently, Chang and Chang proposed a novel three party simple key exchange protocol. Later, Yoon and Yoo presented an Undetectable online password guessing attack on the above protocol. Recently, a password key exchange protocol PSRJ was proposed and also claimed to be in-vulnerable to Undetectable online password guessing attack proposed by Yoon and Yoo. This paper presents a Detectable on-line password guessing attack on PSRJ protocol. Additionally, to overcome the attack, an enhancement over the existing protocol with Exclusive OR operations are proposed.