Raw RNG samples STM32F7: has anyone already tried it?

[MLave.2]

Hi,

I am actually trying to collect raw samples from TRGN module of a STM32F7.

To be more clear, raw sample means unprocessed data coming directly from the source. It is possible using a special IO configuration setup and external equipment in order to collect analogical signals.

Actually this task is not trivial and the effort could be not negligible. So, is there anyone that already performed it?

Are there any data already available?

Thanks,

Marco

[Uwe Bonnes]

Set up RNG, get a sample, write it to UART at high baud rate and collect them in the PC and dissect.

[MLave.2]

Well, actually the setup to collect unprocessed random is quite more complex.

Since I want to avoid post-processing module inside the hw IP, the producer way is to redirect the raw outcomes to GPIO. This is performed by hw, no software routines are involved. So, someone should collect data with external equipment (i.e. oscilloscope/logic analyzer).

Since this is not trivial (I should use at least a 3-channel scope since the random is actually generated from two signal, and obviously a reference clock/trigger is needed), I'm asking if someone has already performed this task and can share some collected data in order to do some preliminary estimations.

[Peter BENSCH]

Welcome, @MLave.2​, to the community!

The STM32F7 contain a TRNG that is fed by analog noise sources, but their analog signals are not accessible from outside. Details on the functionality and the NIST verification, which is based either on the statistical test suite (STS) SP 800-22rev1a (2010-04) or SP 800-90b (2018-01), can be found in the AN4230.

Regards

/Peter

[MLave.2]

Hi Peter,

thank you.

Although no details are shown by reference manual, the TRNG analog sources are redirected as output to PB0 and PB1 using alternate 13.

This allows me to test more deeply the generator. Anyway, I am looking for someone else previous experiences in order to get an idea of what I should expect.

I suppose that it is an uncommon task and my request appears as confusing.