A wireless sensor network designates a wireless network composed of numerous sensor nodes spatially distributed over an area in order to collect information. The sensor nodes communicate wirelessly with each other in order to self-organize into a multi-hop network, collaborate in the sensing activity and forward the acquired information towards a collector node called base station or sink. Due to the collaborative characteristic of such networks, sensor nodes may self-organize into groups to cooperatively monitor environmental conditions or perform tasks. In some critical applications (such as military, healthcare, etc.), information exchanged between group members (sensor nodes) needs to be secured. Therefore, a Secure Group Communication (SGC) scheme must be applied to protect the communication inside the group from potential attacks (such as eavesdropping, injecting, modifying messages, etc.). Moreover, the secure group communication scheme must address the group membership operations (new sensor nodes may join the group, and current sensor nodes can leave the group) to avoid potential attacks such as impersonation, denial-of-service, unauthorized access, etc.