From: Corentin Labbe <clabbe.montjoie@gmail.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: linux-crypto@vger.kernel.org, linus.walleij@linaro.org,
linux-kernel@vger.kernel.org
Subject: Re: cortina/gemini: hwrng: what is its quality ?
Date: Thu, 22 Apr 2021 08:52:23 +0200 [thread overview]
Message-ID: <YIEdJ3G/QwA8/BEU@Red> (raw)
In-Reply-To: <20210422001430.GA4246@gondor.apana.org.au>
Le Thu, Apr 22, 2021 at 10:14:30AM +1000, Herbert Xu a écrit :
> On Wed, Apr 21, 2021 at 10:03:17PM +0200, Corentin Labbe wrote:
> > hello
> >
> > I work on the crypto part of the cortina/gemini SL3516 SoC.
> > The datasheet mention a HWRNG in its IP but really briefly:
> > """
> > The implementation is a 32-bit Hardware Random Number Generator that has a uniformed
> > distribution between 0 and 2^32 -1. The hardware randomness is created by sampling data from
> > different clock domains, and feeding it as input to the 32-bit maximum length LFSR (Linear Feedback
> > Shift Register)
> > """
> >
> > Piping its output to rngtest give:
> > dd if=/dev/hwrng count=2000 bs=2048 | rngtest
> > rngtest 6.11
> > rngtest: starting FIPS tests...
> > rngtest: entropy source drained
> > rngtest: bits received from input: 32768000
> > rngtest: FIPS 140-2 successes: 1191
> > rngtest: FIPS 140-2 failures: 447
> > rngtest: FIPS 140-2(2001-10-10) Monobit: 183
> > rngtest: FIPS 140-2(2001-10-10) Poker: 116
> > rngtest: FIPS 140-2(2001-10-10) Runs: 346
> > 2000+0 records in
> > 2000+0 records out
> > rngtest: FIPS 140-2(2001-10-10) Long run: 0
> > rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
> > rngtest: input channel speed: (min=303.606; avg=3143.352; max=9712.208)Kibits/s
> > rngtest: FIPS tests speed: (min=7.104; avg=10.332; max=10.638)Mibits/s
> > rngtest: Program run time: 13303224 microseconds
> >
> > That's a quite number of failure.
> > Can the hwrng still be used with some "hwrng->quality" setting ?
> > Or it is just too many failure to be used ?
>
> If in doubt just leave it zero and the admin can override it if
> necessary.
>
But as an admin, what value I can set ?
If I do a rule-of-3, success rate is 73%.
So does a quality of 730 is ok ?
next prev parent reply other threads:[~2021-04-22 6:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 20:03 cortina/gemini: hwrng: what is its quality ? Corentin Labbe
2021-04-22 0:14 ` Herbert Xu
2021-04-22 6:52 ` Corentin Labbe [this message]
2021-04-22 7:21 ` Herbert Xu
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