Paper 2011/241

A Novel Adaptive Proactive Secret Sharing without a Trusted Party

Xiuqun Wang

Abstract

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 $$ but also the threshold value $$. An adaptive proactive secret sharing is to refresh the shares as $$ and $$ 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 $$ Byzantine faults in any single time interval, where the number of participants $$. The threshold value $$ and the number of participants $$ can be changed arbitrarily in two adjacent intervals. We also prove that our proposed scheme is secure under the discrete logarithm intractability assumption.