Secure ID-Based Proxy Signcryption Scheme with Designated Proxy Signcrypter

Signcryption is a kind of cryptographic primitive which allows combining the signature and encryption into one scheme efficiently. In this paper we first improve the proxy key generation protocol enforced by Tasi et al and then propose a novel identity based proxy signcryption scheme based on the improved proxy key generation protocol and a identity based signcryption scheme proposed by Libert et al. Our proposed scheme has the merits of strong proxy signature such as verifiability, strong non-forgeability, strong non-deniability, prevention of misuse and message confidentiality.