Identity-based authenticated encryption with identity confidentiality

Abstract

After two decades of research on signcryption, recently a new cryptographic primitive, named higncryption, was proposed at ACM CCS'16. Higncryption can be viewed as privacy-enhanced signcryption, which integrates public key encryption, digital signature and identity concealment (which is not achieved in signcryption) into a monolithic primitive. Here, identity concealment means that the transcript of protocol runs should not leak participants' identity information.In this work, we propose the first identity-based higncryption (IBHigncryption, for short). We present the formal security model for IBHigncryption, under which security proof of the proposed scheme is conducted. The most impressive feature of IBHigncryption, besides other desirable properties it offers, is its simplicity and efficiency, which might be somewhat surprising in retrospect. Our IBHigncryption has a much simpler setup stage with smaller public parameters and particularly no need of computing master public key. It is essentially as efficient as (if not more than) the fundamental CCA-secure Boneh-Franklin identity-based encryption scheme [14], and has significant efficiency advantage over the IEEE 1363.3 standard of identity-based signcryption [8].