International Association for Cryptologic Research (IACR)
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 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