Verifiable Timed Accountable Subgroup Multi-signatures

Abstract

Accountable subgroup multi-signature (ASM) is a form of multi-signature scheme that permits any subgroup of a group to sign a message on behalf of the group while ensuring that the signers are accountable for the multi-signature. Since the accountability principle cannot be provided in many multi-signature schemes, an ASM algorithm makes a difference by providing this feature. ASM has many application areas, especially due to its practical and efficient usage in blockchain or legacy systems. On the other hand, timed signatures allow one to send information to the future which is also necessary for many applications such as blockchain, secure communication, or proof of ownership. In this paper, we propose a timed version of a multi-signature scheme with the help of linearly homomorphic time-lock puzzles (LHTLP) using the method constructed by Thyagarajan et al. Also, we slightly modified the ASM scheme constructed by Boneh et al. to adapt it to the verifiable timed commitment schemes.