Differences between RNG drivers

[Zoptune]

Hi,

I'm working on a project where I need to use an RNG.

I worked with the nrf_drv_rng function with previous SDK but in the latest SDK (15.3) the is nrfx and nrf drivers.
Moreover there is a nrf_crypto_rng driver.

I had performance issues with the legacy nrf_drv_rng driver and I switched to nrf_crypto_rng and it solved the problem.

But I don't understand differences between all these drivers.

Can someone explain me the differences and links between all of them ?

Thanks

[Einar Thorsrud]

Hi,

The nrf_drv_rng uses nrfx_rng for low level handling of the RNG, but provide a more user-friendly API. the nrf_crypto_rng is an even higher level API that is uniform across the RNG peripherals (CC310 RNG and nRF RNG). Moreover, this supports using the RNG peripheral to seed a CTR-DRBG algorithm, which is why you get better performance. I recommend using nrf_crypto_rng unless you have a good reason not to (I cannot think of any).

[Zoptune]

Hi and thank you for your clear answer. I now understand.

I think that the memory impact is higher with the nrf_crypto_rng. Am I wrong ?

Thanks

[Einar Thorsrud]

Yes, the memory impact is higher with nrf_crypto_rng compared to using the RNG peripheral directly. To what degree depend on which backed you use. But that only matters if your design is memory constrained.

[Zoptune]

Ok everything is clear now, thank you :)