Re: [P1363:] 1363.3: Using generalized schemes / choice of pairings
* Does it make sense for all schemes?
Yes
* Does it make sense for some schemes only?
Maybe, not sure about the more esoteric schemes in the standard.
But some academic schemes are NOT secure if instantiated with
a symmetric pairing, or an asymmetric pairing with homomorphism.
- Myself and some others are about to propose a pairing based
DAA scheme with these properties.
- To see this think of the pairing based CL signature scheme in
the various settings, and notice that if 2XDDH (i.e. XDDH in
both groups) holds then the scheme can be made much more efficient,
but if 2XDDH does not hold then the efficiency improvements will
make the scheme insecure.
* Is it too early in the use of IBE to start standardizing
different pairings, and should we focus on a single
interoperable specification?
The exact opposite. It is so early you don't want to exclude something.
For example currently Ate/sextic twists are best at "proper" security
levels (i.e. equivalent to 128-bit AES/256-bit ECC/3000-bit RSA)
as opposed to "academic" security levels (80-bit Block cipher, 160-bit ECC,
1024-bit RSA). It might be that someone finds a really really good way of
making supersingular curves work at these levels, so you dont want to
exclude them (you will still die on bandwidth for ss-curves, but maybe in
some apps you dont care about that).
Nigel
--
Prof. Nigel P. Smart | Phone: +44 (0)117 954 5163
Computer Science Department, | Fax: +44 (0)117 954 5208
Woodland Road, | Email: nigel@xxxxxxxxxxxxx
University of Bristol, BS8 1UB, UK | URL: http://www.cs.bris.ac.uk/~nigel/
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