AES block processing

AN3270

20/23

Doc ID 17919 Rev 2

Figure 16. shows an example of the display of typed text, plain text and cipher text (ASCII

and hex formats).

Figure 16.

Encryption/Decryption result display

3.4

Some recommendations

The firmware implementation of the AES chaining modes provided with this application note

is intended to be used as a starting-point. For many applications, this firmware may be used

as is. However, for applications with tough constraints in terms of code size and/or execution

speed, this firmware may be tailored and simplified to cover only the required features. Refer

to the AES section in the microcontroller’s reference manual RM0031 for more details.

The Direct Memory Access (DMA) can be used to handle input and output phases for better

performance and free the CPU for other tasks

The encryption key can be stored and protected in EEPROM data memory. Refer to the

“Flash program memory and data EEPROM” section in the microcontroller’s reference

manual RM0031.