An efficient code-based threshold ring signature scheme

Abstract

Code based cryptography is a powerful and a promising alternative to the number theoretic cryptography as it is supposed to resist to the quantum computer. The migration to the post quantum hypothetical world requires the design of all the most important cryptographic primitives such as signature schemes. For this reason, we propose in this paper a ring signature and a threshold ring signature schemes that are based on coding theory assumptions. In the case of threshold ring signature scheme, we have a subset of users belonging to a group of users called a ring who collaborate in order to produce a signature on behalf of ring members while maintaining the anonymity of the identity of the real signers. In this paper, we use the AGS identification scheme, which is a coding theory zero-knowledge authentication protocol, to produce a ring signature and a threshold ring signature. By comparing our schemes with the best one in performance so far on 80 bits security level, we find an average 86% reduction of the signature size and also a reduction on the public key length at equivalent security level. The reduction is achieved for different values of the number of signers and ring’s size.