Multicrypt: A Provably Secure Encryption Scheme for Multicast Communication

Multicast communication in dynamic environments like grids and ad hoc networks are potentially of critical concern. As group members move in and out of the group, in order to preserve confidentiality, it becomes imperative to use cryptographic keys with rekeying mechanism each time a user enters or leaves. Therefore, in dynamic environments rekeying introduces a significant computational and communication overhead. The contribution of this paper is mainly twofold: (1) This paper proposes a new architecture for multicast communication (2) Exploiting the orthogonal principle this paper proposes a provably secure n-way cryptosystem (Multicrypt). Multicrypt is a provably secure n-way cryptosystem which uses O(1) keys per user and O(n/m) keys per sub-controller where n is the number of users in the current membership view and m is the number of sub-groups. It supports dynamic member addition and revocation. Multicrypt is proved to be IND-CCA and IND-CCA2 secure.