Identity-based universal re-encryption for mixnets

Abstract

In order to provide anonymity, universal cryptosystems have been used in various applications, including mixnets with multiple receivers. Unlike ordinary re-encryption cryptosystems, universal cryptosystems for re-encryption of ciphertexts do not require knowledge of the public key of the receiver. Golle et al. introduced universal cryptosystems for public key cryptography. Contrary to public key cryptography, in ID-based cryptography, a public key infrastructure is not needed, which makes it suitable for situations where it is not cost-effective to distribute certificates or establish a public key infrastructure. In this paper, we first generalize the definition of universal cryptosystems and the notion of universal semantic security to ID-based cryptography, then we propose two ID-based universal cryptosystem schemes, and lastly we prove the security of these two schemes. The first scheme has higher efficiency in terms of computation and communication while the second scheme has proof of security in the standard model and has a tighter security band. Copyright © 2015 John Wiley & Sons, Ltd.