A method for managing encryption keys in a communication system having a
plurality of communication devices includes establishing a set of
cryptographic keys for secure communication. Each of the cryptographic
keys is associated with a geographic region. A geographic region is
determined for a communication device and at least one cryptographic key
is distributed to the communication device based on the geographic region
of the communication device. At least one cryptographic key may be used
to derive further cryptographic keys associated with a set of sub-regions
of the geographic region associated with the communication device.