Motorola MTM800 Product Information Manual page 88

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11.2 User Authentication
Background:
Authentication is used to prevent an attacker with an unauthorized terminal communicating with an
official infrastructure.
Also to prevent an attacker with a fake infrastructure communicating with an official terminal.
Functionality:
When authentication is used the infrastructure as well as the terminals have to contain an electronic
key string (K) that is provisioned 'In Country' and consists of 12,000,000,000,000,000,000,000,000
possible key combinations.
When the terminal registers on a system both the TEI and the Key are sent to the system, this is
then followed by the terminal's ISSI and the Key. The system will then do a cross check on the
received information with that held in its security centre and if the information is correct it will allow
registry.
Each time the terminal starts a session it will also use a new over the air encryption key and
because of this, it is not possible to work backwards to discover the terminal's electronic key. If
terminals are returned for repair their key have to be removed and to replaced with a new key after
repair.
The 'In Country' Key is replaced on a regular basis.
The terminal supports system initiated user authentication, but not terminal initiated authentication
of the system.
If the terminal is programmed for Mutual Authentication, then whenever the terminal is
authenticated by the system, it will authenticate the system.
Feature description – 2 types of Authentication:
1. 1. Authentication ensures that the official infrastructure "validates" a terminal (initiated by Sys-
tem).
2. 2. Terminals "validate" the infrastructure after an authentication request (initiated by System
made mutual by Terminal) before any voice / data communications can take place.
Agenda to the picture above:
6866537D87-F Chapter 2 - MTM800 Product Information Manual
Services and Feature Description
September 2008