Linkable ring signature scheme based on multivariate polynomial over finite field

Ring signatures serve as a foundational tool for anonymous disclosure of confidential information. Moreover, they can also be customized for e-voting and e-cash with an extra property of linkability. It means that if a user signs more than once, all of his signatures can be linked. In this article, we propose the first linkable ring signature based on multivariate public key cryptography which can be useful against the quantum-equipped adversaries. The robustness of our proposed methodology relies on the computational complexity of multivariate quadratic problems. We deploy Sakumoto et al.'s zero-knowledge protocol and quantum secure Fiat-Shamir transformation for our construction. Our approach successfully fulfils all the requisites for a secure linkable ring signature such as unforgeability, anonymity, non-slanderability, and linkability.