A Novel Adaptive Proactive Secret Sharing without a Trusted Party

A (t + 1, n) proactive secret sharing is to protect a secret in long-lived system by distributing it to a group of n participants and refreshing their shares periodically in this fixed group, while any t+1 and more than t+1 shares can reconstruct the secret. In some environment, it needs to change not only the number of participants n but also the threshold value t. An adaptive proactive secret sharing is to refresh the shares as t and n change. In this paper, we propose a novel adaptive proactive secret sharing scheme without a trusted party. Our proposed scheme is uniformly efficient and tolerates t Byzantine faults in any single time interval, where the number of participants n ≥ 3t+1. The threshold value t and the number of participants n can be changed arbitrarily in two adjacent intervals. We also prove that our proposed scheme is secure under the discrete logarithm intractability assumption.