Atmel Sam Cryptography with CryptoAuth-Xpro-B
This documentation describes the usage of security features for microcontrollers especially for the Atmel Sam R21 with the expansion board Atcryptoauth Xpro B.
The Cryptoauth expansion board contains four chips which gets connected via I2C Chips:
- ATSHA204A (SHA256)
- ATECC508A (Ellipticcurve P256, SHA256)
- ATECC608A (Ellipticcurve P256, SHA256, AES-GCM)
- ATAES132A (AES128)
Implementation for ATECCx08A and ATSHA204A
The example program Implements:
- Showing the serial numbers of the chips
- Hashing a message
- Showing locked zones
- Locking zones
- Generate a random number (only works with locked configuration Zone)
- Generate a keypair (only works with locked configuration Zone)
- Connect your microcontroller to the EDGB USB port and upload the software
- Open a terminal Program (Putty, TeraTerm)
- Terminal program configuration:
Baud rate 115200 Data bits 8 Stop bits 1 Parity none
- Press the restart button in the controller
- The implementation has an text menu which allows you to navigate by numbers
Implementation for ATAES132A
File:AES132ADatasheet.pdf -> that Datasheet is made available from Atmel to get a better understanding of the ATAES132A Chip.
The ATAES132A Chip is NOT based on the Cryptoauthlib. Therefore Atmel doesn't offer complete or functioning example codes for this Chip. There are some example codes that might be working but only for the SAMD21 Xplained Pro board not the SAMR21 Xplained Pro B board, which we are using. I tried to use those example codes, with some changes so it would be working with our board, but I got ERROR messages each time. The main error probably is, that the SAMR21 Xplained Pro Microcontroller is not able to connect to the ATAES132A chip as a I2C slave. Some other problems are, that the example codes for the SAMD21 Xplained Pro board rely too much on that board, so it is nearly impossible to change it for the SAMR21 Xplained Pro B board. Another problem is that Atmel don't even offer an example code to connect to the extension boards, so I wasn't able to check if the ATAES132A chip is working, because no connection could be build. One of the codes is probably working if the connection could be established, because I got a build access and I could load the code onto the board, but I only got negative replies over the Usart.
Here is the link to the projects I tried: 
those User Guides are made available from Atmel to get a better understanding of their products.
- Einführendes Wahlfachprojekt (2019)