Identity-based proxy signature from pairings
A proxy signature scheme allows an entity to delegate itssigning capability to another entity (proxy) in such a way that theproxy can sign messages on behalf of the delegator. Proxy signatureshave found numerous practical applications such as distributed systems,mobile agent applications, etc. Recently, Xu, Zhang and Feng proposedthe first formal models of identity based proxy signature. Unfortunately,their model does not capture the notion of adaptively chosen messageand chosen identity attacker in identity based system. In this paper, weredefine the security models of identity based proxy signature to capturethe most stringent attacks against adaptively chosen message andchosen identity attacker. We also propose a new provably secure identitybasad proxy signature scheme whose security is based on the hardnessof Computational Diffie-Hellman problem in the random oracle model.