Do crypto AEAD functions from SDK 15 work with nRF51?

[Al Bundy]

On the infocenter website we can read that ,,The nRF5 SDK v15.0.0 supports nRF52 Series devices''. I would like to use crypto code from SDK15 on nRF51. I am interested in using AEAD GCM/CCM. By ,,work' I would like to know if these algorithms are also accelerated in hardware on nRF51, so that encryption time is about 200 us?

[Jakub Rzeszutko]

Hi,

I think with some effort you shall be able to port nrf_crypto library to nr51 series.

With nrf_crypto library you can use:

AEAD CCM:

  - CC310 backend: HW accelerated only with nrf52840 (the only uC with Cryptocell)

  - mbed TLS backend - SW implementation

AEAD GCM: It has only SW backend - mbed TLS.

Long story short: with nrf51 you can only use SW backends. HW acceleration is possible only for nrf52840.

The easiest way will be to copy mbedtls library from SDK15 sdk\nrf5\external\mbedtls and port it to your code.

[Al Bundy]

Are you sure that there is HW support for GCM/CCM only on nrf52840? Look at my previous question Long processing time of AEAD EAX. The tests were made on pca10040, which is based on nrf52832 chip.

[Jakub Rzeszutko]

GCM is not HW supported at all. It is SW library from mbed TLS.

CCM is HW supported only on nrf52840. It can be also configured as SW library from mbed TLS.

EAX from Cifra is very very slow SW library.

Some more details you can find here:

http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.0.0/lib_crypto.html?cp=4_0_0_3_11

CC310 - HW accelerated backend

mbed TLS, Oberon, Cifra - SW backends

nrf52832 does not have Cryptocell so it can use only SW backends.