Browse Prior Art Database

METHOD TO DISCOURAGE UNAUTHORIZED USE OF AN APC025 CONVENTIONAL AND TRUNKED SYSTEM

IP.com Disclosure Number: IPCOM000007820D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2002-Apr-25
Document File: 1 page(s) / 52K

Publishing Venue

Motorola

Related People

Hans Sowa: AUTHOR

Abstract

The system is an APCO25 digital 2-way radio conventional system with repeaters, or it is an APCO25 trunking system.

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8 -LA Technical Developments

METHOD TO DISCOURAGE UNAUTHORIZED USE OF AN APC025 CONVENTIONAL AND TRUNKED SYSTEM

by Hans Sowa

SYSTEM BACKGROUND:

  The.system is an APCO25 digital 2-way radio conventional system with repeaters, or it is an APCO25 trunking system.

THE PROBLEM:

  An unauthorized user is using an APCO25 dig- ital repeater in a conventional system. Or an unauthorized user is stealing time on an APCOZS trunking system.

THE SOLUllON:

  All digital voice transmissions will be encrypted by the repeater in the system. So repeater inbound horn a subscriber unit is unencrypted and repeater outbound is encrypted. If an encrypted transmis- sion originates from a subscriber unit, it will be encrypted again by the repeater.

Authorized users in the system will possess the encryption algorithm and encryption key used by

the repeater to encrypt the outbound voice. An unauthorized user will not know the encryption key used.

  Unauthorized users who attempt to use the sys- tem will be able to capture the repeater. However, the repeated voice will be unintelligible to the unauthorized user, thus rendering the system use- less to them.

  The repeated transmissions will be encrypted with Electronic Codebook, so no encryption syn- chronization (Message Indicator) is necessary. This allows the framing format ofthe digital voice to stay the same when the repeater encrypts the voice. Not all voice information needs to be encrypted, since we are only trying to discourage use of the sys...