METHOD TO ENCRYPT TG ID, ALGORITHM ID, AND KEY ID OF A PROJECT 25 TRANSMISSION IN AN ENCRYPTED CONTROL CHANNEL SYSTEM
Original Publication Date: 1996-Nov-01
Included in the Prior Art Database: 2002-May-03
The system is a Project 25 land mobile trunked radio system using an encrypted control channel (CC). The CC is encrypted and uses a message indi- cator (Ml) for the inbound CC and another Ml for the outbound CC. The control channel MIS are incremented on every microslot and are only sent on the CC periodically to save control channel bandwidth. The subscriber unit must increment the CC MIS in order to keep track of them. Voice com- munications are also encrypted and use a different Ml than the CC MIS. The voice Ml is sent as embedded information with the voice.