Browse Prior Art Database

OTAR REKEYING OF A SYSTEM SCANNING OR RAPID ROAMING RADIO

IP.com Disclosure Number: IPCOM000008407D
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2002-Jun-12
Document File: 2 page(s) / 77K

Publishing Venue

Motorola

Related People

Nhat Pham: AUTHOR [+2]

Abstract

The system is conventional Over-The-Air- Rekeying (OTAR) or is trunking OTAR. Radios with encryption may request encryption keys from a Key Management Controller (KMC) by a menu selection that activates a Rekey Request that gives the radio all of the keys it would normally use. Or radios with encryption may be rekeyed with encryp- tion keys as part of a normal rekeying schedule by the KMC.

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MOTOROLA Technical Developments

OTAR REKEYING OF A SYSTEM SCANNING OR RAPID ROAMING RADIO

by Nhat Pham and Hans Christopher Sowa

SYSTEM BACKGROUND

The system is conventional Over-The-Air-

Rekeying (OTAR) or is trunking OTAR. Radios with encryption may request encryption keys from a Key Management Controller (KMC) by a menu selection that activates a Rekey Request that gives the radio all of the keys it would normally use. Or radios with encryption may be rekeyed with encryp- tion keys as part of a normal rekeying schedule by the KMC.

THE PROBLEM

  A secure radio user needs to scan or roam between two systems. Now the radio needs keys for both systems, and potentially could need another Ctypto Group (key index table) for this combination of systems due to limited key storage. Also how does the KMC know what keys to send to the radio'?

  Note that each system is not fast enough to rekey the radio every time it switches systems. Rekeying the radio on switching of systems would also cause considerable data traff?z.

THE SOLUTION

  When the radio user enters scan the radio will request keys for both systems from the KMC and will switch to the new Crypt0 Group (see figure of Cypto Group 3) for both of the systems. The KMC will have the same prestored Crypt0 Group for this purpose and will get the keys needed for both sys- tems and rekey the radio. If the user is going to roam between two systems, without using scan, then some sort of menu will indicate the combina- tion o...