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Message-ID: <2b70efb3-08ef-8de0-d222-4bc29288dde8@collabora.co.uk>
Date:   Tue, 22 Nov 2022 11:55:47 +0100
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Subject: Re: [PATCH] hwrng: u2fzero - account for high quality RNG
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To:     "Jason A. Donenfeld" <Jason@zx2c4.com>,
        herbert@gondor.apana.org.au, linux-crypto@vger.kernel.org
Cc:     Jiri Kosina <jkosina@suse.cz>
References: <20221119134259.2969204-1-Jason@zx2c4.com>
From:   Andrej Shadura <andrew.shadura@collabora.co.uk>
Organization: Collabora
In-Reply-To: <20221119134259.2969204-1-Jason@zx2c4.com>
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On 19/11/2022 14:42, Jason A. Donenfeld wrote:
> The U2F zero apparently has a real TRNG in it with maximum quality, not
> one with quality of "1", which was likely a misinterpretation of the
> field as a boolean. So remove the assignment entirely, so that we get
> the default quality setting.
> 
> In the u2f-zero firmware, the 0x21 RNG command used by this driver is
> handled as such [1]:

> So it seems rather plain that the ATECC RNG is considered to provide
> good random numbers.

Thanks — at the time when it was written, there was a general concern 
about whether we should trust the hardware RNG of this device or not, so 
the safer option was not to :)

> Cc: Andrej Shadura <andrew.shadura@collabora.co.uk>
> Cc: Jiri Kosina <jkosina@suse.cz>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Probably too late, but still:

Acked-by: Andrej Shadura <andrew.shadura@collabora.co.uk>

-- 
Cheers,
   Andrej