Figure 3-39. Apx 2000/ Apx 4000 Encryption Architecture - Motorola APX 1000 Detailed Service Manual

Theory of Operation
: Controller
3.2.7 Encryption
The encryption circuitry is placed on the keypad board and interfaces to the main board through the
J2301-P2001 connector. The encryption circuitry is designed to digitally encrypt and decrypt voice
and ASTRO data in the APX 2000/ APX 4000 radio. The Motorola Advanced Crypto Engine (MACE)
IC is the main component in the encryption design, and has some discrete support circuitry along
with the interfaces to the main board IC's (CPLD, OMAP, and Audio CODEC).
NOTE: The MACE IC is NOT serviceable. The information contained in this section is only intended
to help determine whether a problem is due to the MACE IC or the radio itself.
Figure 3-39 below shows the Encryption architecture for the APX 2000/ APX 4000 radio.
AUDIO
CODEC
As shown in Figure 3-39
• MACE IC
• Key Loading
• Key Retention
• Tamper
• Key Zeroize.
SSI
Key Key
Retention Fail

Figure 3-39. APX 2000/ APX 4000 Encryption Architecture

above, the encryption design consists of 5 blocks:
CPLD
CLK SSI GPIO
MACE
(Secure IC)
Tamper
OMAP
SSI
Key
Zeroize
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