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From: Stephan Mueller <smueller@chronox.de>
To: Corentin Labbe <clabbe.montjoie@gmail.com>
Cc: herbert@gondor.apana.org.au, davem@davemloft.net,
	maxime.ripard@free-electrons.com, wens@csie.org,
	linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] crypto: sun4i-ss: support the Security System PRNG
Date: Thu, 17 Nov 2016 09:18:46 +0100	[thread overview]
Message-ID: <2474504.KOMlLBWsmD@tauon.atsec.com> (raw)
In-Reply-To: <20161117080748.GB25394@Red>

Am Donnerstag, 17. November 2016, 09:07:48 CET schrieb Corentin Labbe:

Hi Corentin,
> 
> Seed again, or just do not seed (and so return -EAGAIN for read() function)
> until ready_callback ?

This is your choice. But for the start sequence, you should not simply rely on 
get_random_bytes.

For the DRBG in crypto/drbg.c we seed with get_random_bytes and the Jitter RNG 
in case the input_pool is not fully seeded. The reseed trigger is reduced to 
50 DRBG requests, i.e. after 50 requests, the DRBG again reseeds from 
get_random_bytes / Jitter RNG. This is continued until the input_pool has been 
sufficiently seeded (i.e. the registered callback is triggered). At that 
point, another get_random_bytes call is made, the Jitter RNG is deactivated 
and the reseed threshold is set to the common value.

Ciao
Stephan

WARNING: multiple messages have this Message-ID (diff)
From: smueller@chronox.de (Stephan Mueller)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] crypto: sun4i-ss: support the Security System PRNG
Date: Thu, 17 Nov 2016 09:18:46 +0100	[thread overview]
Message-ID: <2474504.KOMlLBWsmD@tauon.atsec.com> (raw)
In-Reply-To: <20161117080748.GB25394@Red>

Am Donnerstag, 17. November 2016, 09:07:48 CET schrieb Corentin Labbe:

Hi Corentin,
> 
> Seed again, or just do not seed (and so return -EAGAIN for read() function)
> until ready_callback ?

This is your choice. But for the start sequence, you should not simply rely on 
get_random_bytes.

For the DRBG in crypto/drbg.c we seed with get_random_bytes and the Jitter RNG 
in case the input_pool is not fully seeded. The reseed trigger is reduced to 
50 DRBG requests, i.e. after 50 requests, the DRBG again reseeds from 
get_random_bytes / Jitter RNG. This is continued until the input_pool has been 
sufficiently seeded (i.e. the registered callback is triggered). At that 
point, another get_random_bytes call is made, the Jitter RNG is deactivated 
and the reseed threshold is set to the common value.

Ciao
Stephan

  reply	other threads:[~2016-11-17  8:18 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-18 12:34 [PATCH] crypto: sun4i-ss: support the Security System PRNG Corentin Labbe
2016-10-18 12:34 ` Corentin Labbe
2016-10-18 14:24 ` Stephan Mueller
2016-10-18 14:24   ` Stephan Mueller
2016-11-17  8:07   ` Corentin Labbe
2016-11-17  8:07     ` Corentin Labbe
2016-11-17  8:18     ` Stephan Mueller [this message]
2016-11-17  8:18       ` Stephan Mueller
2016-10-18 16:09 ` PrasannaKumar Muralidharan
2016-10-18 16:09   ` PrasannaKumar Muralidharan
2016-11-17  8:05   ` Corentin Labbe
2016-11-17  8:05     ` Corentin Labbe
2016-11-18  1:07 ` Sandy Harris
2016-11-18  1:07   ` Sandy Harris
2016-11-18  7:55   ` Corentin Labbe
2016-11-18  7:55     ` Corentin Labbe
  -- strict thread matches above, loose matches on Subject: below --
2017-06-20  8:58 Corentin Labbe
2017-06-20  8:58 ` Corentin Labbe
2017-06-20  8:58 ` Corentin Labbe
2017-06-20  9:59 ` Maxime Ripard
2017-06-20  9:59   ` Maxime Ripard
2017-06-20 11:45   ` Corentin Labbe
2017-06-20 11:45     ` Corentin Labbe
2017-06-21  6:48     ` Maxime Ripard
2017-06-21  6:48       ` Maxime Ripard
2017-06-21 23:47       ` Herbert Xu
2017-06-21 23:47         ` Herbert Xu

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