Redistributing secret shares to new access structures and its applications

Proactive secret sharing deals with refreshing secret shares i e redistributing the shares of a secret to the original access structure In this paper we focus on the general problem of redistributing shares of a secret key Shares of a secret have been distributed such that access sets speci ed in the access structure e g t out of l can access or use the secret The problem is how to redistribute the secret without recovering it in such a way that those speci ed in the new access structure will be able to recover the secret We also adapt our scheme such that it can be used in the context of threshold cryptography and discuss its applications to secure databases