In the field of cryptography, the three-party authenticated key exchange protocol is an important tool, especially in the secure communication areas. In this protocol, two clients share a human-memorable password with a trusted server whereby the two clients receive a secure session key. Most recently, Huang proposed a simple and efficient three party password-based key exchange protocol. She claimed that the proposed protocol is secure against various attacks. However, Yoon and Yoo proved an undetectable online password guessing attack on Huang's protocol. In the present paper, an unknown key share attack on Huang's three party PAKE protocol using undetectable online password guessing attack is demonstrated. Additionally, an alternative protocol that eliminates this attack is proposed. Moreover, the proposed protocol requires only four message transmission rounds.

ABSTRACT

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Abstract-In the secure communication areas, three-party authenticated key exchange protocol is an important cryptographic technique. In this protocol, two clients will share a human-memorable password with a trusted server, in which two users can generate a secure session key. On the other hand the protocol should resist all types of password guessing attacks. Recently, STPKE' protocol has been proposed by Kim and Choi. An undetectable online password guessing attack on STPKE' protocol is presented in the current study. An alternative protocol to overcome undetectable online password guessing attacks is proposed. The results show that the proposed protocol can resist undetectable online password guessing attacks. Additionally, it achieves the same security level with reduced random numbers and without XOR operations. The computational efficiency is improved by ≈ 30% for problems of size ≈ 2048 bits. The proposed protocol is achieving better performance efficiency and withstands password guessing attacks. The results show that the proposed protocol is secure, efficient and practical.

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