Browse Prior Art Database

OTAR ALGORITHM

IP.com Disclosure Number: IPCOM000007478D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2002-Mar-29
Document File: 1 page(s) / 55K

Publishing Venue

Motorola

Related People

Dan Naylor: AUTHOR

Abstract

The system is conventional or trunked Over-The- Air-Rekeying (OTAR). A Key Management Control- ler (KMC) is used to send encryption keys to radios. Radios have a Key Encryption Key (KEK) in com- mon with the KMC. This allows the KMC to send traffic encryption keys (TEKs), over-the-air, encrypted with the KEK, to the radio. TEKs are used for voice traffic in the system.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 72% of the total text.

Page 1 of 1

M-ROLA Technical Developments

8

OTAR ALGORITHM

by Dan Naylor

SYSTEM BACKGROUND:

THE SOLUTION:

  The system is conventional or trunked Over-The- Air-Rekeying (OTAR). A Key Management Control- ler (KMC) is used to send encryption keys to radios. Radios have a Key Encryption Key (KEK) in com- mon with the KMC. This allows the KMC to send traffic encryption keys (TEKs), over-the-air, encrypted with the KEK, to the radio. TEKs are used for voice traffic in the system.

  The solution proposes to change the algorithm that the radio uses for over-the-air voice or data traf- fic when the radio changes systems. Two approaches can be used here. First, the algorithms that the radio uses are in software and we can change this sot?- ware over-the-air. Second, an encryption device with a programmable algorithm, such as a Motorola DVI encryption device, is modified such that the algo- rithm can be programmed multiple times.

  When a radio roams into a new OTAR system it will be programmed over the air with the new algo- rithm, the new algorithm KEK, and test verifica- tion data for the new algorithm. This information will be sent encrypted over-the-air using the old algo- rithm KEK. Once the radio verities the new algo- rithm using the test verification data, it will switch over to the new algorithm and the radio will respond with an acknowledgement to the new KMC. Once the KMC receives the acknowledgement, the KMC will send a normal rekey of TEKs to the unit using the new algorithm K...