Does anyone know why Entropy Drivers is grayed out in kconfig?

[Jan Erik]

Hi,

I'm trying to enable the entropy driver so that sys_csrand_get() will stop returning "Entropy reseed error".

Does anyone know why it's grayed out?

I have tried enabling all cc310 options as well, just in case that was a dependency.

[Didrik Rokhaug]

Hi.

I'll need some more details from you:

Which NCS version are you using?

What board (and chip) are you trying to build for?

I believe this is the documentation for the option you are looking for: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.3.0/kconfig/CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR.html#cmdoption-arg-config-entropy-device-random-generator

Best regards,

Didrik

[Jan Erik]

Hi, this is nrf9160 non-secure.
NCS master branch.

I don't necessarily need to turn on this option specifically, as long as I can get sys_csrand_get() to stop throwing -EIO.

[Didrik Rokhaug]

Is there a particular reason for why you want to use sys_csrand_get()?

The CC310 can only be used in secure mode, while an nRF9160 application must run as non-secure to be able to use the modem.

However, you can use the 'secure_services' library to request a random number from the SPM. The SPM will then use the on-board random number generator to provide a true random number: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.3.0/nrf/include/secure_services.html#_CPPv425spm_request_random_numberP4u8_t6size_tP6size_t

[Jan Erik]

Thanks, I'll check that out.

I just need random numbers for an encryption IV