Authenticated Diffie-Hellman Key Agreement Scheme that Protects Client Anonymity and Achieves Half-Forward Secrecy

Abstract

Authenticated Diffie-Hellman key agreement (D-H key) is the de facto building block for establishing secure session keys in many security systems. Regarding the computations of authenticated D-H key agreement, the operation of modular exponentiation is the most expensive computation, which incurs a heavy loading on those clients where either their computational capacities or their batteries are limited and precious. As client's privacy is a big concern in several e-commerce applications, it is desirable to extend authenticated D-H key agreement to protect client's identity privacy. This paper proposes a new problem: the modified elliptic curves computational Diffie-Hellman problem (MECDHP) and proves that the MECDHP is as hard as the conventional elliptic curves computational Diffie-Hellman problem (ECDHP). Based on the MECDHP, we propose an authenticated D-H key agreement scheme which greatly improves client computational efficiency and protects client's anonymity from outsiders. This new scheme is attractive to those applications where the clients need identity protection and lightweight computation.