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Browse Prior Art Database

ALL KEYS SIGNATURE IN INVENTORY COMMAND

IP.com Disclosure Number: IPCOM000009758D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2002-Sep-17
Document File: 2 page(s) / 82K

Publishing Venue

Motorola

Related People

Bhavesh S. Shah: AUTHOR [+2]

Abstract

In an ASTRO 25 Over The Air Rekeying (OTAR) system, the Key Management Facility (KMF) distributes keys to all secure components in the system. Ideally, only the KMF should be able to configure keys in any unit. But, that is not the case. A user can change the keys via the Key Variable Loader (KVL) or also erase the keys in the unit without KMF's knowledge. This would make the unit and KMF out of sync with each other.

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MOTOROLA

Technical Developments

ALL KEYS SIGNATURE IN INVENTORY COMMAND

by Bhavesh S. Shah and Brett Szudy

BACKGROUND/PROBLEM

In an ASTRO 25 Over The Air Rekeying (OTAR) system, the Key Management Facility (KMF) distributes keys to all secure components in the system.

Ideally, only the KMF should be able to configure keys in any unit. But, that is not the case. A user can change the keys via the Key Variable Loader (KVL) or also erase the keys in the unit without KMF's knowledge. This would make the unit and KMF out of sync with each other.

There is an Inventory command in APCO standards, which can be used to get all the KIDs (Key Identifiers) present in the unit. But in case the unit has several keys, the response can get quite long and it might be time consuming for KMF to check all the keys. Also, when we consider the several thousands of units in a system, it will be really cumbersome for KMF to verify all keys in all units.

SOLUTION

We can add a new Inventory type - All Keys Signature to the APCO OTAR standard. The KMF can calculate the signature and store it in the unit's record. All units can calculate some signature involving all the keys in the database and send it back to the KMF as inventory response.

Motorola. Inc. 2000

The KMF can now match the signatures and determine whether the unit is in sync with others.

The algorithm to calculate this signature must be independent of the key storage mechanism in different secure units. First, an order-dependent CRC is calc...