The recent growth of multimedia group of applications is driving the need for secure multicast communication. Secure multicast communication in dynamic environments like wireless networks and grids are potentially of critical concern. As multicast group members move in and out of the group, in order to preserve confidentiality, it becomes imperative to use cryptographic keys with rekeying mechanism. Therefore, rekeying introduces a significant computational and communication overhead. A specific encryption mechanism rather a general one is needed to suit the multicast communication requirements wherein the life time of a secret key is very short and requires frequent change. Moreover, the next generation wireless networks have very limited resources and need a light weight security mechanism.This paper defines the requirements of a multicast cryptographic method and proposes an encryption scheme for multicast communication. The encryption scheme uses a new mathematical tool, namely orthogonal vectors for performing cryptographic operations. The proposed encryption scheme is designed to be light weight and have dynamic key revocation and addition properties. The proposed encryption scheme is robust against brute force attack.