Efficient identity-based signcryption without random oracles

Abstract

In this paper, we propose a new Identity-based signcryption (IBSC) scheme in the standard model. Our scheme shows an improvement of approximately 40% reduction in the ciphertext size when compared to the previously proposed IBSC schemes in the standard model. Further, we argue that the previous IBSC schemes do not provide sufficient simulation ability in the security game. We show that with some minor overhead, we are able to correct this. The security reduction of our scheme is based on the hardness of the hashed modified decision bilinear Diffie-Hellman problem and the modified computational Diffie-Hellman problem. © 2012, Australian Computer Society, Inc.