Abstract: Methods and apparatus are provided for secure communication techniques in a communication system. The system can include a first device which communicates with a second device over a channel. A security association can be established during a first session between the devices via an asymmetric key exchange. The security association comprises a Traffic Encryption Key (TEK) and a first state vector. The TEK comprises a shared, secret symmetric key. The security association is stored in each of the devices for use during a second session between the devices to expedite security association establishment during call set-up of the second session. The security association can be associated with the second device in the first device, and with the first device in the second device. An updated state vector can be generated at the first device. A second session can be established between the first device and the second device by using the TEKs from the first session and the updated state vector.

Abstract: Techniques are provided for secure group communications in a wireless dispatch system which includes a group of devices. The group of devices can include a first secure device which communicates with a plurality of second secure devices over a channel.

Abstract: An apparatus (213) and corresponding methods (FIG. 7) to facilitate maintaining crypto synchronization while processing communication signals in a communication unit includes a vocoder (215) configured to convert input audio band signals to vocoder output frames; a crypto processor (217) configured to encrypt the vocoder output frames to provide encrypted output frames; and a synchronizer (219) configured to substitute in a predetermined manner synchronization information corresponding to an encryption state of the crypto processor for a portion of the encrypted data in a portion of the encrypted output frames to provide resultant output synchronization frames suitable for synchronizing a decryption process at a target communication unit.

Abstract: An apparatus (213) and corresponding methods (FIG. 7) to facilitate maintaining crypto synchronization while processing communication signals in a communication unit includes a vocoder (215) configured to convert input audio band signals to vocoder output frames; a crypto processor (217) configured to encrypt the vocoder output frames to provide encrypted output frames; and a synchronizer (219) configured to substitute in a predetermined manner synchronization information corresponding to an encryption state of the crypto processor for a portion of the encrypted data in a portion of the encrypted output frames to provide resultant output synchronization frames suitable for synchronizing a decryption process at a target communication unit.