Use of the ARM CryptoCell for cryptography-related operations?

[applecuckoo]

I've seen that Adafruit have an Arduino crypto library for the nRF52 series, and according to Nordic's documentation it seems it covers the cryptography functions that are implemented in CircuitPython, namely AES and hashing. Are there any specific reasons why the CryptoCell can't be used in the CircuitPython implementation.

[jepler]

I thought os.urandom was expected to work on nrf52:

circuitpython/ports/nrf/common-hal/os/__init__.c

Line 66 in 50e259f

bool common_hal_os_urandom(uint8_t *buffer, mp_uint_t length) {

What are you seeing when you try to call it? I don't have any nrf boards handy to test.

[applecuckoo]

Ah - my bad, seems like the documentation from https://docs.circuitpython.org/en/latest/shared-bindings/os/index.html#os.urandom is outdated, it told me that it wasn't available on nRF52 boards. The point still stands about the CryptoCell being used for AES and hashing.

[jepler]

Aha, thanks--I'm going to file a separate issue about the incorrect documentation so this issue can be specifically about the use of trust cell.

[jepler]

• doc: nrf has urandom #7851

[tannewt]

Are there any specific reasons why the CryptoCell can't be used in the CircuitPython implementation.

Not that I know of. We just haven't added it.

[applecuckoo]

Pinging @hathach for his work on the Adafruit_nRFCrypto Arduino library.