Patent ID: 7738663

Claim:
A method of allocating a security key to each node of a communication system having N nodes, the method comprising: grouping N nodes into a first group and a second group, such that each group comprises N/2 nodes, no node is shared between the groups, and N is an even integer; grouping the first group into a plurality of sub-groups, such that each of the plurality of sub-groups comprises at least two different nodes and at least one of the two different nodes differs from at least one of the nodes in other sub groups; allocating a different first security key to each sub-group such that the first security keys are not shared among the plurality of sub-groups; allocating, to each node of the first group, B/2 second security keys from a total of B second security keys, such that each node of the first group has a different set of B/2 second security keys, B is an even integer, and B is equal to N−2; allocating first security keys to the nodes of the second group such that the first security keys allocated to the corresponding nodes of the second group is the same as the first security keys allocated to the corresponding nodes of the first group; and allocating, to a (K)th node of the second group, B/2 second security keys that are not allocated to a corresponding (K)th node of the first group.