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Appendix A
Secure Modules:
NTN7282A, and
NTN7283A for
MTS 2000 Radios
Circuit Description
The Secure Module is NOT serviceable. The
information contained in this appendix is only
meant to help determine whether a problem is
due to the Secure Module or the radio itself.
The Secure Module is designed to digitally encrypt and decrypt voice
data in Motorola's MTS 2000 Series Handie-Talkie™ Portable Radios.
The Secure Module uses a custom encryption integrated circuit (IC)
and an encryption key variable to perform its encode/decode function.
The encryption key variable is loaded into the Secure Module via the
radio's universal (side) connector from a hand held key variable loader.
The encryption IC corresponds to the particular encryption algorithm
purchased. The encryption algorithms and their corresponding kit
numbers are:
• Data Encryption Standard (DES)NTN7279A
• Digital Voice Protection (DVP)NTN7281A
The Secure Module, shown in Appendix Figure 1, operates from two
power supplies. The first 5 volt supply (Vdd) is received from the
controller board through connector plug P1 pin 2. This Vdd supply is
turned on and off with the radio on/off switch. The second supply
(UNSW B+) is received from the controller board through connector
Plug P1 pin 1. UNSW B+ provides power to the Secure Module as long
as the radio battery is in place.
Key variables are loaded into the Secure Module through connector P1
pins 13, 15, and 16. One key variable can be stored in the module at a
time. The key variable is stored in volatile electronic memory, so it can
only remain in memory as long as the radio is connected to a charged
battery. If the battery is removed or if the battery fails, then a capacitor
will allow the module to retain the key variable for at least 30 seconds
while the battery is being replaced.
The radio's host processor communicates with the Secure Module on
the Serial Peripheral Interface (SPI) bus. The host processor is the
master on this bus, while the Secure Module is a slave on the bus. The
Appendix A- 1


This manual also for:

Jt-1000, Mt-2000, Mts-2000

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