Efficient and Adaptive Threshold Signatures for Ad hoc networks

In this paper, we propose a secure, flexible, robust and fully distributed signature service, for ad hoc groups. In order to provide the service, we use a new threshold scheme, that allows to share a secret key among the current group members. The novelty of the scheme is in that it easily and efficiently enables dynamic increase of the threshold, according to the needs of the group, so that the service provides both adaptiveness to the level of threat the ad hoc group is subject to, and availability. We prove the correctness of the protocol and evaluate its efficiency. The changes to the threshold are performed by using a protocol that is efficient in terms of interactions among nodes and per-node required resources, resulting suitable even for resource-constrained settings. Finally, the same proposed scheme allows to detect nodes that attempt to disrupt the service, providing invalid contributions to the distributed signature service.