mOT+: An efficient and secure identity-based diffie-hellman protocol over RSA group

Abstract

In 2010, Rosario Gennaro et al. revisited the old and elegant Okamoto-Tanaka scheme and presented a variant of it called mOT. How-ever the compromise of ephemeral private key will lead to the leakage of the session key and the user’s static private key. In this paper, we propose an improved version of mOT(denoted as mOT+). Moreover, based on RSA assumption and CDH assumption we provide a tight and intuitive security reduction in the id-eCK model. Without any extra computa-tional cost, mOT+ achieves security in the id-eCK model, and further-more it also meets full perfect forward secrecy against active adversary.