Existing ad hoc routing protocols are either unicast or multicast. In this paper we propose a simple extension to the Dynamic Source Routing Protocol (DSR) to cater for group communications where all node addresses are unicast and there is no single multicast address. The proposed sliding window protocol results in significant improvement in total packet delivery. We also compare the group rekeying rate using the sliding window protocol versus other kinds of Rekeying algorithms. The proposed sliding window protocol performs better. The proposed sliding window is therefore simple and improves both communications and security performance.