Identity-based chameleon hash scheme without key exposure

Abstract

The notion of chameleon hash function without key exposure plays an important role in designing chameleon signatures. However, all of the existing key-exposure free chameleon hash schemes are presented in the setting of certificate-based systems. In 2009, Ateniese and de Medeiros questioned whether there is an efficient construction for identity-based chameleon hashing without key exposure.

In this paper, we propose the first identity-based chameleon hash scheme without key exposure based on the three-trapdoor mechanism, which provides an affirmative answer to the open problem.