Details of the RNG hardware for true randomness

[daviddedwin]

Hi,

I am selecting a Bluetooth IC based on the availability of true randomness in it and the nRF52832 is in the list.

"The Random number generator (RNG) generates true non-deterministic random numbers based on internal
thermal noise that are suitable for cryptographic purposes."

1. Can you provide more details on how the true randomness is achieved by the RNG peripheral using thermal noise.

2. I am aware that as the temperature is lowered the speed of the random number generation is reduced, can you provide some approximations on how the speed of the random number generation is reduced ?

Thanks
David

[Simonr]

Hi David

The RNG module is designed to meet the requirements in Bluetooth. The RNG has been tested in-house according to the NIST SP 800-22 statistical test suite. This has not been certified by an external test house as of yet.

Best regards,

Simon

[daviddedwin]

Hi Simon,

Thanks for the reference, I am aware the of specification and the requirement to comply to that spec by all Bluetooth vendors, however my question is a bit different. I will try to expand my question so you can understand better.

This is what is present in the nRF52832 PS, section 26 RNG — Random number generator.
"The Random number generator (RNG) generates true non-deterministic random numbers based on internal
thermal noise that are suitable for cryptographic purposes."

This evaluation has explicitly stated that we need true random numbers. The question is about the physical process of thermal noise and its usage in the nRF52832 to generate the randomness and the temperature dependency of such a process.

Please assist.

Thanks for your support
David

[Simonr]

Hi David

I'm sorry, but we do not provide any further details about the RNG module than what is already described in the PS.

Best regards,

Simon

[daviddedwin]

Ok, so there is no justification to the statement in the PS that this is indeed a "true non-deterministic random number".

[daviddedwin]

RNG information provided. Case can be closed.