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Date:      Tue, 1 Mar 2005 16:53:45 -0800
From:      "Ted Mittelstaedt" <tedm@toybox.placo.com>
To:        "Kris Kennaway" <kris@obsecurity.org>
Cc:        FreeBSD questions <freebsd-questions@freebsd.org>
Subject:   RE: /dev/io , /dev/mem : only used by Xorg?
Message-ID:  <LOBBIFDAGNMAMLGJJCKNEEJPFAAA.tedm@toybox.placo.com>
In-Reply-To: <20050301092901.GB95093@xor.obsecurity.org>

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> -----Original Message-----
> From: Kris Kennaway [mailto:kris@obsecurity.org]
> Sent: Tuesday, March 01, 2005 1:29 AM
> To: Ted Mittelstaedt
> Cc: Kris Kennaway; Loren M. Lang; Rob; FreeBSD questions
> Subject: Re: /dev/io , /dev/mem : only used by Xorg?
>
>
> On Tue, Mar 01, 2005 at 12:06:11AM -0800, Ted Mittelstaedt wrote:
>
> > >> Another strange thing is that /dev/random should block when it
> > >> runs out of entropy - it doesen't seem to do so, however.  And the
> > >> device doesen't seem to gain entropy that quickly.
> > >
> > > No, it should not block because it's not defined to block
> >
> > In FreeBSD
> >
> > > and that
> > > would be a bad interface anyway.
> >
> > The "u" in /dev/urandom means unblocking.
>
> It also means "return stuff even when you have no more entropy".
> Can't get there from here.
>

Presumably the app writer knows this.

Come now, I never said it was a -good- interface.  The ideas of how
the random device should work are somewhat of a moving target among
UNIXes.  The yarrow generator is one of the better ones us ordinary
mortals
have access to, I wonder what the NSA uses?

Ted



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