The distribution of keys in a Conditional Access System (CAS) takes large computation time, since the number of keys to be updated is high. Moreover, it is necessary to send the keys securely to the authorized group members. In this paper, we propose a new Key Distribution Protocol that reduces the computation time taken to compute the re-keying information whenever there is a change in the group membership. In the proposed system, when the Group Centre needs to refresh a new group key, only few encryption/decryption operations are needed. Two primary operations that are performed by the service providers and members are XOR and multiplication, in which computation load is very less. From the experiments carried out in this work, it has been observed that the computation time is reduced in this work when compared with the existing systems. © 2012 Springer-Verlag.