A code-based hybrid signcryption scheme

TL;DR

This paper introduces a novel code-based hybrid signcryption scheme that combines signature and encryption, utilizing a tag-KEM approach with security proofs against IND-CCA2 and SUF-CMA attacks.

Contribution

It presents the first code-based signcryption tag-KEM scheme using subcode equivalence and provides security analysis in the standard model.

Findings

Secure against IND-CCA2 and SUF-CMA attacks

Uses subcode equivalence as a security assumption

Achieves hybrid signcryption with proven security

Abstract

A key encapsulation mechanism (KEM) that takes as input an arbitrary string, i.e., a tag, is known as tag-KEM, while a scheme that combines signature and encryption is called signcryption. In this paper, we present a code-based signcryption tag-KEM scheme. We utilize a code-based signature and an IND-CCA2 (adaptive chosen ciphertext attack) secure version of McEliece's encryption scheme. The proposed scheme uses an equivalent subcode as a public code for the receiver, making the NPcompleteness of the subcode equivalence problem to be one of our main security assumptions. We then base the signcryption tag-KEM to design a code-based hybrid signcryption scheme. A hybrid scheme deploys asymmetric- as well as symmetric-key encryption. We give security analyses of both our schemes in the standard model and prove that they are secure against IND-CCA2 (indistinguishability under adaptive chosen ciphertext attack) and SUF-CMA (strong existential unforgeability under chosen message attack).