Re: [PATCH 1/2] hwrng: iproc-rng200 - Set the quality value

It was <2020-05-15 pią 11:10>, when Stephan Mueller wrote:

As I mentioned, all that is or seems to be analyzed here is the
quality of the cryptographic post-processing. Thus none of the data
can be used for getting an idea of the entropy content.

That said, the ent value indeed looks too low which seems to be an
issue in the tool itself.

Note, for an entropy assessment commonly at least 1 million traces
from the raw noise source are needed.

I've got 1MiB from each source. Of course I used raw data from /dev/hwrng
for tpm, exynos and rng200.

| Source       | ea_iid -i | ea_iid -c (h') |      ent |
|--------------+-----------+----------------+----------|
| /dev/random  |  7.875064 |       0.998166 | 7.999801 |
| /dev/urandom |  7.879351 |       0.998373 | 7.999821 |
| tpm-rng      |  7.880012 |       0.998118 | 7.999828 |
| exynos-trng  |  7.435701 |       0.947574 | 7.991820 |
| rng200       |  7.883320 |       0.998592 | 7.999824 |

See for examples on how such entropy assessments are conducted in the LRNG 
documentation [1] or the Linux /dev/random implementation in [2]

Thanks a lot, I am reading.

I will try to write somthing clever as soon as I parse and understand
these documents (and do other stuff too). Thank you very much for your help.

Kind regards,
-- 
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics