A method of reducing the number of security keys allocated to each node of a wireless network, and of reducing the number of security keys that are required by the wireless network. N nodes are grouped into a first and a second groups, each group comprising N/2 nodes without nodes being shared. The first group is grouped such that at least two nodes are included and at least one node is different, and first security keys are allocated to the first group nodes without any security keys being shared among the groups. (N/2) groups are grouped to include a security key arrangement of (B/2) number of security keys of B number of second security keys, and the second security keys of each group are allocated to each node of the first group. Here, the security key arrangement of each group differs from that of the others.