Browse Prior Art Database

KEK AND RSI RESYNCHRONIZATION

IP.com Disclosure Number: IPCOM000008547D
Original Publication Date: 1998-Mar-01
Included in the Prior Art Database: 2002-Jun-21
Document File: 2 page(s) / 86K

Publishing Venue

Motorola

Related People

Paul Wadzinske: AUTHOR [+2]

Abstract

In APCO OTAR, the unique Key Encryption Key (UKEK) or Radio Set Identifier (RSI) that an individual unit has can become out of sync with the UKEK or RSI that the Key Management Facility (KMF) believes that the unit possesses. This scenario occurs when a radio has been successfully sent a new UKEK or RSI, but an OTAR acknowl- edgment to the rekey or change RSI command is not successfully received by the KMF. The acknowledgment coming back to the KMF can collide with other inbound traffic and be prevented from reaching the KMF.

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 50% of the total text.

Page 1 of 2

0 M MO-LA

Technical Deve1opment.s

KEK AND RSI RESYNCHRONIZATION

by Paul Wadzinske and Michelle Chang

INTRODUCTION AND PRIOR ART

  In APCO OTAR, the unique Key Encryption Key (UKEK) or Radio Set Identifier (RSI) that an individual unit has can become out of sync with the UKEK or RSI that the Key Management Facility (KMF) believes that the unit possesses. This scenario occurs when a radio has been successfully sent a new UKEK or RSI, but an OTAR acknowl- edgment to the rekey or change RSI command is not successfully received by the KMF. The acknowledgment coming back to the KMF can collide with other inbound traffic and be prevented from reaching the KMF.

KMF Radio

not recognize the one sent to it from the KMF.

SOLUTION

  This invention will prevent the above scenario from occurring. We will use the UKEK example to illustrate its operation. When the user changes a unit's UKEK, the KMF remembers the UKEK that it thinks the radio currently possesses, i.e. "current UKEK" as well as the new UKEK assigned to the radio, i.e "latest UKEK." When the KMF is updating the radio's UKEK, it will keep track of whether or not the radio successfully acknowledged the new UKEK. If it did, the KMF will update the radio's "current UKEK" to be equal to the "latest UKEK." Otherwise, it will keep these two values separate.

  When the user performs a subsequent rekey operation on the radio, the KMF will first of all determine if the radio's "current UKEK" is equal to the "latest UKEK." If it is, the KMF will perform the Traffic Encrypt...