A secret sharing scheme permits a secret to be shared among participants in such a way that only qualiied subsets of participants can recover the secret, but any non-qualiied subset has absolutely no information on the secret. In this paper we consider the problem of designing eecient secret sharing schemes having the additional feature that qualiied minorities can forbid any other set of parti...

Key agreement is a fundamental security functionality by which pairs of nodes agree on shared keys to be used for protecting their pairwise communications. In this work we study key-agreement schemes that are well-suited for the mobile network environment. Specifically, we describe schemes with the following characteristics: • Non-interactive: any two nodes can compute a unique shared secret ke...

Assume that there are players and an eavesdropper Eve of unlimited computational power and that several pairs of players have shared secret keys beforehand. A key sharing graph is one in which each vertex corresponds to a player, and each edge corresponds to a secret key shared by the two players corresponding to the ends of the edge. Given a key sharing graph, a player wishes to send a message...

The ( ) , t n threshold secret sharing scheme proposed by Shamir (1979) encodes the secret key into n shares and those shares are distributed among the participants. Each share incorporates an x-value uniquely designated for every single participant. If the shares are distributed on insecure (or public) channels, malicious users may acquire a few (or all) shares. If the number of shares obtaine...