Security for group addressed data packets in wireless networks

A wireless network includes a border router, multiple router nodes and end devices. All nodes of the wireless network use a same group key for encryption and decryption of payloads of multicast layer-2 packets. A router node of the wireless network receives a group key from its parent node, and forwards the group key to its child nodes. The router node receives a layer-2 multicast packet with a payload specifying a multicast layer-3 address. The router node decrypts the payload using the group key. If at least one child node of the router node belongs to a group corresponding to the multicast layer-3 address, the router node forwards the encrypted payload as a layer-2 multicast packet to corresponding child nodes. Use of a same group key across all nodes of the wireless network reduces storage space in a node for storing group keys, and also simplifies group key handling.