It was <2020-05-15 pią 10:32>, when Stephan Mueller wrote: > Am Freitag, 15. Mai 2020, 00:18:41 CEST schrieb Lukasz Stelmach: > >> I am running tests using SP800-90B tools and the first issue I can see >> is the warning that samples contain less than 1e6 bytes of data. I know >> little about maths behind random number generators, but I have noticed >> that the bigger chunk of data from an RNG I feed into either ent or ea_iid >> the higher entropy they report. That is why I divided the data into 1024 >> bit chunks in the first place. To get worse results. With ea_iid they >> get even worse (128 bytes of random data) > > I read that you seem to just take the output data from the RNG. If this is > correct, I think we can stop right here. The output of an RNG is usually after > post-processing commonly provided by a cryptographic function. > > Thus, when processing the output of the RNG all what we measure here is the > quality of the cryptographic post-processing and not the entropy that may be > present in the data. > > What we need is to access the noise source and analyze this with the given > tool set. And yes, the analysis may require adjusting the data to a format > that can be consumed and analyzed by the statistical tests. I took data from /dev/hwrng which is directly connected to the hardware. See rng_dev_read() in drivers/char/hw_random/core.c. -- Łukasz Stelmach Samsung R&D Institute Poland Samsung Electronics
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