From: "Theodore Ts'o" <tytso@mit.edu>
To: "Lasse Kärkkäinen" <ljkarkk2@cc.hut.fi>
Cc: linux-kernel@vger.kernel.org
Subject: Re: urandom is too slow
Date: Tue, 30 Oct 2012 14:54:03 -0400 [thread overview]
Message-ID: <20121030185403.GA5044@thunk.org> (raw)
In-Reply-To: <508FEA5A.7010406@cc.hut.fi>
On Tue, Oct 30, 2012 at 04:55:22PM +0200, Lasse Kärkkäinen wrote:
> Apparently there has been little or no development on urandom even
> though the device is in widespread use for disk shredding and such
> use. The device emits data at rather slow rate of 19 MB/s even on
> modern hardware where other software-based PRNGs could do far
> better. An even better option seems to be utilizing AES for
> encrypting zeroes, using a random key, allowing for rates up to 500
> MB/s with hardware that has AES-NI instructions.
>
> Why is urandom so slow and why isn't AES hardware acceleration utilized?
If you can use a software-based PRNG, you should use one in userspace.
The intended use of urandom is for cryptographic purposes (i.e.,
generating random session keys, long-term public keys, etc.). If you
just want to wipe a disk, you shouldn't be using /dev/urandom for that
purpose.
Regards,
- Ted
next prev parent reply other threads:[~2012-10-30 18:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-30 14:55 urandom is too slow Lasse Kärkkäinen
2012-10-30 18:54 ` Theodore Ts'o [this message]
2012-10-30 20:56 ` Pádraig Brady
2012-10-30 21:38 ` Alan Cox
2012-11-02 1:10 ` Lasse Kärkkäinen
2012-11-02 19:56 ` Theodore Ts'o
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