Re: [Cfrg] IBE checking...

"Paterson, Kenny" <Kenny.Paterson@rhul.ac.uk> Mon, 21 March 2016 17:09 UTC

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From: "Paterson, Kenny" <Kenny.Paterson@rhul.ac.uk>
To: Tanja Lange <tanja@hyperelliptic.org>, Stephen Farrell <stephen.farrell@cs.tcd.ie>
Thread-Topic: [Cfrg] IBE checking...
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Date: Mon, 21 Mar 2016 17:09:37 +0000
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References: <546A1ABC.2010505@cs.tcd.ie> <56F00956.2010600@cs.tcd.ie> <20160321150939.GJ17551@ein.win.tue.nl>
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Cc: "cfrg@irtf.org" <Cfrg@irtf.org>
Subject: Re: [Cfrg] IBE checking...
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Hi

From the specification, it's pretty clear that this proposal does not use
pairings:

>In common
>with other identity-based encryption/signature approaches, it is
>based on the use of elliptic curves.  Unlike some, it does not use
>"pairings" (bilinear maps from a product of two elliptic curve groups
>to another group).


So the recent analysis in eprint 2015/1027 is not relevant here.

Cheers

Kenny

On 21/03/2016 15:09, "Cfrg on behalf of Tanja Lange"
<cfrg-bounces@irtf.org on behalf of tanja@hyperelliptic.org> wrote:

>Dear Stephen, dear all,
>> While I'm not a fan of IBE myself, and there's still no published
>> analyses, I don't think we can block experimental stuff for those
>> reasons alone. (Otherwise CFRG might have a hard time producing
>> some new experimental specs for example.) Mind you, that does
>> assume that the rest of the world know the difference between
>> experimental and standards-track RFCs, which is not actually
>> true, but we do also need to stick with the rules of the game
>> that we've setup so I think this is the correct, if not the
>> optimal, outcome.
>> 
>There is ongoing work on breaking the discrete log problem in the
>target group (the group where the pairing maps to). The most
>recent publication I'm aware of is
>	https://eprint.iacr.org/2015/1027
>
>At ECC 2015 Aurore Guillevic gave a talk
>Computing individual discrete logarithms faster in F_{p^n} with the
>Number Field Sieve algorithm
>in which she is targeting fields with 1<=n<=12, which are exactly the
>fields appearing as targets of pairings. For abstract and slides see
>	http://ecc2015.math.u-bordeaux1.fr/index.php?category=conference&page=pro
>gramme
>So, at this moment I'd suggest some caution for parameter suggestions.
>
>All the best
>	Tanja
>
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