Re: [hybi] "fresh" and "uniformly at random":

"Arman Djusupov" <arman@noemax.com> Mon, 20 June 2011 14:10 UTC

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From: "Arman Djusupov" <arman@noemax.com>
To: "'Adam Barth'" <ietf@adambarth.com>, "'Denis Lagno'" <dilmah@chromium.org>
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Date: Mon, 20 Jun 2011 17:09:35 +0300
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Cc: hybi@ietf.org
Subject: Re: [hybi] "fresh" and "uniformly at random":
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I think you actually mean that the implementation should not intentionally
reuse a mask or part of a mask.

With best regards,
Arman

> -----Original Message-----
> From: Adam Barth [mailto:ietf@adambarth.com]
> Sent: Monday, June 20, 2011 11:05 AM
> To: Denis Lagno
> Cc: Arman Djusupov; hybi@ietf.org
> Subject: Re: [hybi] "fresh" and "uniformly at random":
> 
> Yeah, that was a confusing way of putting it.  I meant that the underlying
> coin-flips should not have been used previously.
> 
> Adam
> 
> 
> On Mon, Jun 20, 2011 at 12:34 AM, Denis Lagno <dilmah@chromium.org>
> wrote:
> > oh, well, so you'd better avoid phrase "not used previously" in the
> > first place.  It was highly misleading.
> >
> > On Mon, Jun 20, 2011 at 11:31 AM, Adam Barth <ietf@adambarth.com>
> wrote:
> >> You can sensibly apply the term fresh to 1-bit values if you like.
> >> The important aspect is independence from your previous choices.
> >>
> >> Adam
> >>
> >>
> >> On Mon, Jun 20, 2011 at 12:26 AM, Denis Lagno <dilmah@chromium.org>
> wrote:
> >>> maybe I miss something but in the text "fresh" is applied to 32-bit
> values..
> >>>
> >>> On Mon, Jun 20, 2011 at 6:57 AM, Adam Barth <ietf@adambarth.com>
> wrote:
> >>>> On Sat, Jun 18, 2011 at 12:34 AM, Denis Lagno <dilmah@chromium.org>
> wrote:
> >>>>> On Sat, Jun 18, 2011 at 10:27 AM, Adam Barth <ietf@adambarth.com>
> wrote:
> >>>>>> The term "fresh" is a term of art in cryptography.  It means,
> >>>>>> roughly, "not used previously."
> >>>>>
> >>>>> So this implies that client must keep track of already used keys?
> >>>>> it imposes limit on length of connection?
> >>>>> True it or false, It should be explicitly clarified in the text.
> >>>>
> >>>> The normal practice in cryptography is to just use large enough
> >>>> values such that the probably of collision is sufficiently small as
> >>>> to be acceptable.  For example, if you use a 20 byte nonce, the
> >>>> probably of collision is zero for all practical purposes.
> >>>>
> >>>> This stuff is all extremely normal.
> >>>>
> >>>> Adam
> >>>>
> >>>
> >>
> >