Encryption Module; Table 3-6. Encryption Module Software Kits And Algorithms - Motorola ASTRO XTS 5000 Detailed Service Manual

3-34
The radio power-down sequence begins by opening the radio On/Off switch, which removes the
B+SENSE signal from the VOCON board. This does not immediately remove power because the
GCAP II IC has control of Q502 through Vref, and U301 through WDI maintains the GCAP II IC in an
active state. Both the MCU and Flipper IC monitor B+SENSE. After B+SENSE is removed, the
Flipper IC waits 125 ms. before releasing WDI to allow for software cleanup; however, the software
has the ability to prolong this time if it was necessary to complete its operations. When WDI is
released, the GCAP II IC shuts down its supplies and the rest of the radio through Q501.
3.3

Encryption Module

The encryption module (secure models only) connects directly to the VOCON board and interfaces
directly with the vocoder digital circuitry. It contains an independent microcontroller and two custom
ICs to perform digital, numerical, encryption algorithms.
The encryption modules are designed to digitally encrypt and decrypt voice and ASTRO data in
ASTRO XTS 5000 radios. This section covers the encryption modules, hardware kits NTN9738 and
NNTN5032.
NOTE: The encryption modules are NOT serviceable. The information contained in this section is
only intended to help determine whether a problem is due to a encryption module or the radio
itself.
The encryption module uses a custom encryption IC and an encryption key variable to perform its
encode/decode function. The encryption key variable is loaded into the encryption module, via the
radio's universal (side) connector, from a hand-held, key variable loader (KVL). The encryption IC
corresponds to the particular encryption algorithm purchased.
algorithms and their corresponding kit numbers.
Software
Kit Number
NNTN4006
NTN9837
NTN9838
NTN9839
NNTN4197
NNTN4198
The encryption module operates from two power supplies (UNSW_B+ and SW_B+). The SW_B+ is
turned on and off by the radio's On/Off switch. The UNSW_B+ provides power to the encryption
module as long as the radio battery is in place.
Key variables are loaded into the encryption module through connector J701, pin 1. Depending on
the type of encryption module, up to 16 keys can be stored in the module at a time. The key can be
infinite key retention or 30-seconds key retention, depending on how the codeplug is set up.
The radio' s host processor communicates with the encryption module on the Synchronous Serial
Interface (SSI) bus. The SSI bus consists of five signal lines. A communications failure between the
host processor and the secure module will be indicated as an ERROR 09/10 message on the
display.
To troubleshoot the encryption module, refer to the flowcharts in
July 21, 2004

Table 3-6. Encryption Module Software Kits and Algorithms

DES, DES-XL, DES-OFB
DES, DES-XL, DES-OFB WITH DVP-XL
DVI-XL
DVP-XL
AES
AES with DES, DES-XL, DES-OFB
Theory of Operation
Table 3-6 lists the encryption
Algorithm
Chapter 5 "Troubleshooting Charts."
: Encryption Module
6881094C31-D