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From: "H. Peter Anvin" <hpa@zytor.com>
To: Stephan Mueller <smueller@chronox.de>, "Theodore Ts'o" <tytso@mit.edu>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
	Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
	linux-crypto@vger.kernel.org, andi@firstfloor.org,
	sandyinchina@gmail.com, jsd@av8n.com
Subject: Re: [PATCH 5/7] random: replace non-blocking pool with a Chacha20-based CRNG
Date: Mon, 20 Jun 2016 11:52:10 -0700	[thread overview]
Message-ID: <b9ce7eec-e573-f187-feb5-b1110313f2ac@zytor.com> (raw)
In-Reply-To: <2101992.L9gKN5cFdv@tauon.atsec.com>

On 06/20/16 08:49, Stephan Mueller wrote:
> Am Montag, 20. Juni 2016, 11:01:47 schrieb Theodore Ts'o:
> 
> Hi Theodore,
> 
>>
>> So simply doing chacha20 encryption in a tight loop in the kernel
>> might not be a good proxy for what would actually happen in real life
>> when someone calls getrandom(2).  (Another good question to ask is
>> when someone might be needing to generate millions of 256-bit session
>> keys per second, when the D-H setup, even if you were using ECCDH,
>> would be largely dominating the time for the connection setup anyway.)
> 
> Is speed everything we should care about? What about:
> 
> - offloading of crypto operation from the CPU
> 

This sounds like a speed operation (and very unlikely to be a win given
the usage).

> - potentially additional security features a hardware cipher may provide like 
> cache coloring attack resistance?

How about burning that bridge when and if we get to it?  It sounds very
hypothetical.

I guess I could add in some comments here about how a lot of these
problems can be eliminated by offloading an entire DRNG into hardware,
but I don't think it is productive.

	-hpa

  reply	other threads:[~2016-06-20 20:30 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-13 15:48 [PATCH-v4 0/7] random: replace urandom pool with a CRNG Theodore Ts'o
2016-06-13 15:48 ` [PATCH 1/7] random: initialize the non-blocking pool via add_hwgenerator_randomness() Theodore Ts'o
2016-06-13 15:48 ` [PATCH 2/7] random: print a warning for the first ten uninitialized random users Theodore Ts'o
2016-06-13 15:48 ` [PATCH 3/7] random: add interrupt callback to VMBus IRQ handler Theodore Ts'o
2016-06-13 15:48 ` [PATCH 4/7] random: properly align get_random_int_hash Theodore Ts'o
2016-06-13 15:48 ` [PATCH 5/7] random: replace non-blocking pool with a Chacha20-based CRNG Theodore Ts'o
2016-06-13 18:00   ` Stephan Mueller
2016-06-13 19:03     ` Theodore Ts'o
2016-06-15 14:59   ` Herbert Xu
2016-06-19 23:18     ` Theodore Ts'o
2016-06-20  1:25       ` Herbert Xu
2016-06-20  5:02         ` Theodore Ts'o
2016-06-20  5:19           ` Herbert Xu
2016-06-20 15:01             ` Theodore Ts'o
2016-06-20 15:49               ` Stephan Mueller
2016-06-20 18:52                 ` H. Peter Anvin [this message]
2016-06-20 23:48                 ` Theodore Ts'o
2016-06-26 18:47       ` Pavel Machek
2016-06-26 19:10         ` Stephan Mueller
2016-06-26 22:51         ` Theodore Ts'o
2016-06-13 15:48 ` [PATCH 6/7] random: make /dev/urandom scalable for silly userspace programs Theodore Ts'o
2016-08-21  9:53   ` Jan Varho
2016-08-21 11:36     ` Theodore Ts'o
2016-06-13 15:48 ` [PATCH 7/7] random: add backtracking protection to the CRNG Theodore Ts'o
2016-06-26 18:47   ` Pavel Machek
2016-06-26 23:05     ` Theodore Ts'o

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