February 14, 2012 6816985H01-F
4.5-16 900 MHz Detailed Theories of Operation: VOCON Functional Blocks
4.5.6.3.5 Encryption Module
The encryption module (secure models only) connects directly to the VOCON board and interfaces
directly with the vocoder digital circuitry. It contains one custom microcontroller IC (Armour) to
perform digital, numerical, encryption algorithms.
The encryption modules are designed to digitally encrypt and decrypt voice for ASTRO and
NON-ASTRO in XTS 2500/XTS 2500
I. This section covers the encryption modules, hardware kits
0104020J49 (Model 1.5), 0104020J50 (Model 2) and 0104020J51 (Model 3).
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 an 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. Table 4.5-2 lists the encryption
algorithms and their corresponding kit numbers.
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 J601, pin 34. 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 four signal lines. A communications failure between the
host processor and the secure module will be ERROR 09/10 or S03 error message on the display.
To troubleshoot the encryption module, refer to the flowcharts in Chapter 6.5 “900 MHz
Troubleshooting Charts.”
Table 4.5-2. Encryption Module Software Kits and Algorithms
Software
Kit Number
Algorithm
Q667AB (7/
800), Q667AE
(V,U1,U2)
ADP SFWR DSP BASED CRYPTO
Q159AC XTS 2500/XTS 2500
I UCM HARDWARE ENCRYPTION
Q629AD AES ENCRYPTION
Q625AU DES, DES-XL, DES-OFB ENCRYPTION
Q668AC ADP UCM ENCRYPTION W/DES, DES-XL, DES-OFB
H869BQ MULTI KEY
Q406AC ADP UCM ENCRYPTION
QA00204AA MULTIKEY AND ADP
ADP UCM ENCRYPTION W/AES
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