C8051F960-B-GM Datasheet, PDF (179/492 Pages) Silicon Laboratories – Ultra Low Power 128K, LCD MCU Family

C8051F96x
14.2. Key Inversion
The Key output is used to generate an inverse key. To generate a decryption key from an encryption key,
the AES core should be configured for an encryption operation. Dummy data and the encryption key are
written to the AES0BIN and AES0KIN sfrs respectively. The output multiplexer should be configured to out-
put the decryption key to the AES0YOUT SFR.
internal state
machine
AES0BIN
+
AES0XIN
AES0DCFG
AES0KIN
AES0BCFG
Data In
Key
AES
Key
In
Core
Out
Data Out
+
AES0YOUT
Figure 14.2. Key Inversion Data Flow
The dummy data may be zeros or arbitrary data. The content of the dummy data does not matter. But six-
teen bytes of data must be written to the AES0BIN sfr to generate the inverse key.
Rev. 1.0
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