Abstract: Roaming encryption key rekeying apparatus and method comprising a first system key management facility that communicates to a communication unit roaming information is disclosed. The roaming information is encrypted using a first encryption scheme that is decipherable by the communication unit. Further, the first system key management facility communicates to a second system key management facility the roaming information. In this communication, the roaming information is encrypted as a function of a second encryption scheme that is decipherable by the second system key management facility.

Abstract: A communication system comprises a first plurality of remote stations (107, 109, 111) belonging to a first call group (119) having an associated first encryption key and a first encryption mode. A second plurality of remote stations (113, 115) belongs to a second call group (121) having an associated second encryption key and a second encryption mode. A group controller (117) forms a third call group (123) which comprises the first and the second call groups (119, 123) and which has an associated third encryption key. When communicating on the third, combined call group, the first plurality of remote stations (107, 109, 111) use the third encryption key and the first encryption mode whereas the second plurality of remote stations (113, 115) use the third encryption key and the second encryption mode.

Abstract: A plurality of storage location numbers (“SLNs”), each having a cryptographic period, is received at a first device (100). A system cryptographic period is determined based on the SLN cryptographic periods. Prior to expiration of each system cryptographic period, if at least one SLN requires an updated, the first device sends updated key material for the at least one SLN. A second device (102) maintains first, second, and third keysets, wherein the first and second keysets comprise key material. The second device receives a message to make the first keyset active, and a second message for updating at least a portion of the key material in the second keyset with updated key material for at least one SLN. The second device makes the third keyset equivalent to the second keyset, updates the second keyset with the updated key material, and receives a third message to make the second keyset active.