From: Krzysztof Kozlowski <krzk@kernel.org>
To: Stephan Mueller <smueller@chronox.de>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Arnd Bergmann <arnd@arndb.de>,
Matthias Brugger <mbrugger@suse.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Matt Mackall <mpm@selenic.com>,
Lukasz Stelmach <l.stelmach@samsung.com>,
Scott Branden <sbranden@broadcom.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-samsung-soc@vger.kernel.org"
<linux-samsung-soc@vger.kernel.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Kukjin Kim <kgene@kernel.org>,
bcm-kernel-feedback-list@broadcom.com,
Stefan Wahren <wahrenst@gmx.net>, Ray Jui <rjui@broadcom.com>,
Markus Elfring <elfring@users.sourceforge.net>,
linux-arm-kernel@lists.infradead.org,
linux-crypto@vger.kernel.org
Subject: Re: [PATCH v2 1/2] hwrng: iproc-rng200 - Set the quality value
Date: Wed, 20 May 2020 14:00:01 +0200 [thread overview]
Message-ID: <CAJKOXPeBkZ3R2wT9-A8LWkFx0W9KY70VW7JNjwp0RMDRc7hkTg@mail.gmail.com> (raw)
In-Reply-To: <2041475.ybOAuNAZB8@tauon.chronox.de>
On Wed, 20 May 2020 at 13:53, Stephan Mueller <smueller@chronox.de> 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
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next prev parent reply other threads:[~2020-05-20 12:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200514190737eucas1p18ccdddb185ea7611683a6859e17bc721@eucas1p1.samsung.com>
2020-05-14 19:07 ` [PATCH 0/2] Set the quality value for two HW RNGs Łukasz Stelmach
[not found] ` <CGME20200514190738eucas1p2695c0d8af064ee702209ca03696ef438@eucas1p2.samsung.com>
2020-05-14 19:07 ` [PATCH 1/2] hwrng: iproc-rng200 - Set the quality value Łukasz Stelmach
2020-05-14 20:20 ` Stephan Mueller
[not found] ` <CGME20200514221852eucas1p2bea169d0b4467b0ec9e195c6ac58a08a@eucas1p2.samsung.com>
2020-05-14 22:18 ` Lukasz Stelmach
2020-05-15 8:32 ` Stephan Mueller
[not found] ` <CGME20200515090647eucas1p21018edfd835730c9a68dcb186349ee74@eucas1p2.samsung.com>
2020-05-15 9:06 ` Lukasz Stelmach
[not found] ` <CGME20200515090158eucas1p1b653fc50f1ad4f0f6c92525ab3188d45@eucas1p1.samsung.com>
2020-05-15 9:01 ` Lukasz Stelmach
2020-05-15 9:10 ` Stephan Mueller
[not found] ` <CGME20200515110002eucas1p136759396d9b61f214d1f14856c009501@eucas1p1.samsung.com>
2020-05-15 10:59 ` Lukasz Stelmach
[not found] ` <CGME20200514190740eucas1p293129b2ef3ba706652a9327e55db9649@eucas1p2.samsung.com>
2020-05-14 19:07 ` [PATCH 2/2] hwrng: exynos " Łukasz Stelmach
2020-05-14 20:20 ` Stephan Mueller
[not found] ` <CGME20200519212617eucas1p1b6e7af0ecb894896b165601fafd6abe8@eucas1p1.samsung.com>
2020-05-19 21:25 ` [PATCH v2 0/2] Set the quality value for two HW RNGs Łukasz Stelmach
[not found] ` <CGME20200519212619eucas1p22fa5d3db2521096dc4b79f6e53016d17@eucas1p2.samsung.com>
2020-05-19 21:25 ` [PATCH v2 1/2] hwrng: iproc-rng200 - Set the quality value Łukasz Stelmach
2020-05-20 6:23 ` Stephan Mueller
[not found] ` <CGME20200520091043eucas1p15ecae108007382a95b01e42241cc7a26@eucas1p1.samsung.com>
2020-05-20 9:10 ` Lukasz Stelmach
2020-05-20 9:18 ` Stephan Mueller
[not found] ` <CGME20200520104448eucas1p122e9a8ed84d5276a1b796e10ef5e1964@eucas1p1.samsung.com>
2020-05-20 10:44 ` Lukasz Stelmach
2020-05-20 11:53 ` Stephan Mueller
2020-05-20 12:00 ` Krzysztof Kozlowski [this message]
2020-05-20 12:11 ` Stephan Mueller
[not found] ` <CGME20200520143211eucas1p21bd93be5c62726aa715db05bb6e7119b@eucas1p2.samsung.com>
2020-05-20 14:31 ` Lukasz Stelmach
2020-05-20 8:18 ` Kamil Konieczny
2020-05-21 11:00 ` Stefan Wahren
[not found] ` <CGME20200521191415eucas1p2d112a86171b23dcf255e7da53a56f4f3@eucas1p2.samsung.com>
2020-05-21 19:14 ` Lukasz Stelmach
2020-05-23 18:46 ` Stephan Müller
[not found] ` <CGME20200519212621eucas1p13279db41d930b69e115972463c994a37@eucas1p1.samsung.com>
2020-05-19 21:25 ` [PATCH v2 2/2] hwrng: exynos " Łukasz Stelmach
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