Browse Prior Art Database

METHOD TO DETERMINE TG ENCRYPTION KEY IN VLR WHEN HLR IS NOT AVAILABLE

IP.com Disclosure Number: IPCOM000008256D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2002-May-30
Document File: 1 page(s) / 58K

Publishing Venue

Motorola

Related People

Hans Christopher Sowa: AUTHOR

Abstract

The system is a secure multikey 2-way radio trunked OminiLink system. An OminiLink system consists of many zones and each zone has a Zone Controller (ZC). A talkgroup (TG) is assigned to a zone which is then called its controlling zone (CZ). The CZ has the HLR for the TG which contains the encryption key number for the console to use with that secure TG. Other zones that are involved with the call are called participating zones (PZ). The key number information at a PZ is stored in a VLR.

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M6FC)IROLA Technical Developments

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METHOD TO DETERMINE TG ENCRYPTION KEY IN VLR WHEN HLR IS NOT AVAILABLE

by Hans Christopher Sowa

SYSTEM BACKGROUND

  The system is a secure multikey 2-way radio trunked OminiLink system. An OminiLink system consists of many zones and each zone has a Zone Controller (ZC). A talkgroup (TG) is assigned to a zone which is then called its controlling zone (CZ). The CZ has the HLR for the TG which contains the encryption key number for the console to use with that secure TG. Other zones that are involved with the call are called participating zones (PZ). The key number information at a PZ is stored in a VLR.

  A key number is a pointer to'a key. The key number specified in the HLR refers to a key loca- tion in a Digital Interface Unit (DIU). A Key ID is a unique identifier for an encryption key. The Key ID is sent embedded with secure voice transmissions.

  The key number for the same encryption key in a radio or DIU most likely will not be the same key number. The keys most likely will be stored in different locations between the radio and DIU. The Key ID for the same encryption key will be the same in a radio or DIU.

THE PROBLEM

  Under certain conditions, a console in a PZ may not have access to the key number. The VLR may not have been updated from the HLR or an inter- zone link is down blocking access to the HLR. The VLR needs to access the HLR in order to get the key number for the TG. Not knowing the key number for a TG can cause a sec...