Stateless forward-secure key-insulated linkable ring signature scheme in ID-based setting

Abstract

Forward-security and key-insulation have been the mainstream antidotes to the key exposure problem in conventional and ring signatures primarily in the setting of public key infrastructure. However, all extant schemes require keeping state of time periods. Moreover, time-bound keys are stored for retrieval during key update and more importantly signature-related dispute resolution which may extend beyond stipulated time periods. Spurred on by the gravity of key exposure in the setting of identity-based cryptography, we introduce a stateless forward-secure key-insulated linkable ring signature accomplished partly with on-demand ephemeral secret keys consequently eliminating the need for state-keeping and long-term storage. We prove security of our construction in the Random Oracle Model based on intractable problems of Computational Diffie–Hellman (CDH) and Discrete Logarithm (DL). Subsequently, we present evaluation results from a comparative analysis of extant identity-based linkable ring signature schemes to attest to the uniqueness, convenience and efficiency of our scheme which incidentally compared to state-of-the-art achieves a running time of 22.113ms faster at verification phase making it the fastest compared to extant schemes aside the statelessness and constant linkability attributes.