From: Theodore Ts'o <tytso@mit.edu>
To: Stephan Mueller <smueller@chronox.de>
Cc: Aaron Zauner <azet@azet.org>,
linux-crypto@vger.kernel.org,
Sandy Harris <sandyinchina@gmail.com>
Subject: Re: AES-NI: slower than aes-generic?
Date: Mon, 30 May 2016 00:08:03 -0400 [thread overview]
Message-ID: <20160530040803.GB12629@thunk.org> (raw)
In-Reply-To: <7574982.B7hkDJezet@positron.chronox.de>
On Sun, May 29, 2016 at 09:51:59PM +0200, Stephan Mueller wrote:
>
> I personally am not sure that taking some arbitrary cipher and turning it into
> a DRNG by simply using a self-feeding loop based on the ideas of X9.31
> Appendix A2.4 is good. Chacha20 is a good cipher, but is it equally good for a
> DRNG? I do not know. There are too little assessments from mathematicians out
> there regarding that topic.
If ChCha20 is a good (stream) cipher, it must be a good DRNG by
definition. In other words, if you can predict the output of
ChaCha20-base DRNG with any accuracy greater than chance, this can be
used as a wedge to attack the stream cipher..
I will note that OpenBSD's "ARC4" random number generator is currently
using ChaCha20, BTW.
Regards,
- Ted
prev parent reply other threads:[~2016-05-30 4:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-26 16:10 AES-NI: slower than aes-generic? Stephan Mueller
2016-05-26 17:25 ` Jeffrey Walton
2016-05-26 17:30 ` Stephan Mueller
2016-05-26 18:14 ` Stephan Mueller
2016-05-26 18:20 ` Sandy Harris
2016-05-26 18:49 ` Stephan Mueller
2016-05-26 19:15 ` Sandy Harris
2016-05-27 2:14 ` Theodore Ts'o
2016-05-27 7:08 ` Stephan Mueller
2016-05-27 20:40 ` Jeffrey Walton
2016-06-08 12:21 ` Stephan Mueller
2016-05-28 0:28 ` Aaron Zauner
2016-05-29 19:51 ` Stephan Mueller
2016-05-30 4:08 ` Theodore Ts'o [this message]
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