Identity based proxy-signcryption scheme from pairings

An identity-based cryptosystem is a novel type of public cryptographic scheme in which the public keys of the users are their identities or strings derived from their identities. A signcryption is a primitive that provides private and authenticated delivery of messages between two parties. Proxy signature schemes are variations of ordinary digital signature schemes and have been shown to be useful in many applications. We proposed an identity-based proxy-signcryption scheme from pairings. Also we analyze the proposed scheme from efficiency and security points of view. Heuristic arguments have been given for those security properties. We have shown that the proxy-signcryption scheme is as efficient as ordinary identity-based signcryption schemes under certain circumstances.