On Wed, 20 May 2020 at 13:53, Stephan Mueller <smueller@xxxxxxxxxx> wrote: > > > That said, the illustrated example is typical for hardware RNGs. Yet > > > it is never guaranteed to work that way. Thus, if you can point to > > > architecture documentation of your specific hardware RNGs showing that > > > the data read from the hardware is pure unconditioned noise data, then > > > I have no objections to the patch. > > > > I can tell for sure that this is the case for exynos-trng[1]. > > So you are saying that the output for the exynos-trng is straight from a ring > oscillator without any post-processing of any kind? Hi, I think we will never be able to state this because the manual is quite limited in sharing internals. What the driver does and probably Lukasz wanted to say is that there is "post processing" block and feature which can be disabled. The manual is saying the TRNG block generates random data from thermal noise but not how much in a direct way. There could be some simple post-processing or not (except the one able to on/off). Also manual says this post processing block is there to remove statistical weakness from the TRNG block. To me it does not prove enough that raw data is really raw... Best regards, Krzysztof
