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Date:   Tue, 17 Sep 2019 18:20:02 +0100
From:   Matthew Garrett <mjg59@srcf.ucam.org>
To:     Willy Tarreau <w@1wt.eu>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Martin Steigerwald <martin@lichtvoll.de>,
        "Ahmed S. Darwish" <darwish.07@gmail.com>,
        "Theodore Y. Ts'o" <tytso@mit.edu>,
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        Lennart Poettering <mzxreary@0pointer.de>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Jan Kara <jack@suse.cz>, Ray Strode <rstrode@redhat.com>,
        William Jon McCann <mccann@jhu.edu>,
        "Alexander E. Patrakov" <patrakov@gmail.com>,
        zhangjs <zachary@baishancloud.com>, linux-ext4@vger.kernel.org,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: Linux 5.3-rc8
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On Tue, Sep 17, 2019 at 07:16:41PM +0200, Willy Tarreau wrote:
> On Tue, Sep 17, 2019 at 05:34:56PM +0100, Matthew Garrett wrote:
> > On Tue, Sep 17, 2019 at 09:27:44AM -0700, Linus Torvalds wrote:
> > 
> > > Does anybody believe that 128 bits of randomness is a good basis for a
> > > long-term secure key?
> > 
> > Yes, it's exactly what you'd expect for an AES 128 key, which is still 
> > considered to be secure.
> 
> AES keys are for symmetrical encryption and thus as such are short-lived.
> We're back to what Linus was saying about the fact that our urandom is
> already very good for such use cases, it should just not be used to
> produce long-lived keys (i.e. asymmetrical).

AES keys are used for a variety of long-lived purposes (eg, disk 
encryption).
 
-- 
Matthew Garrett | mjg59@srcf.ucam.org