Secret Key Sharing Using Homomorphic Commitments and its application to Threshold Cryptography

摘要

In mobile ad hoc networks, the misbehaving nodes can cause dysfunction of the network resulting in the damage of other nodes. In order to establish secure communication with the group members of a network Threshold cryptography is employed, where a secret key is divided into multiple shares by a cryptographic operation. This technique is useful to provide a shared secret key to master nodes in a infrastructure-less mobile ad-hoc network (MANET). This scheme only considers the situation when all participating users are legitimate shareholders. Traditionally, the dealer (master node) is trusted, however, this does not always hold. This paper proposes a new technique for the group formation and selecting a Group Head (master node), where the group head is responsible for sharing the secret key among the group members The sub-shares can be generated either by using iterative subshare calculation or parallel subshare calculation. This paper also proposes a technique to identify the legitimate nodes for the secret reconstruction using homomorphic commitments and further for the encryption and decryption of messages. Proactive Secret Sharing (PSS) scheme allows all shares to be refreshed by generating a new set of shares for the same secret key. All shareholders must cooperate with the PSS procedure for the protocol consistency. In addition to the above, this paper also proposes a protocol for PSS synchronization.