Re: [Cfrg] Elliptic Curves - poll on specific curve around 256bit work factor (ends on February 23rd)

[Ilari Liusvaara <[e-mail]>]

On Sun, Feb 22, 2015 at 05:37:17PM +0100, Kurt Roeckx wrote:
> On Wed, Feb 18, 2015 at 10:51:16AM +0000, Alexey Melnikov wrote:
> > CFRG chairs are starting another poll:
> > 
> > Q3: (For people who want CFRG to recommend a curve at 256bit level) Is
> > bandwidth cost of going to p521 worth the speed win over primes closer to
> > 512 bits?
> 
> So if I understand the question, this is about speed versus
> bandwidth?  I haven't seen anybody argue that bandwidth is a
> concern.  Depending on who you ask you might get a different
> answer, but I doubt many people here care about bandwidth.
> 
> I also have to wonder how much bandwidth difference there would
> be.  If this is in the order of a few bytes per connection I doubt
> you can get many people excited about this.

AFAICT: +4 bytes for ECDHE, +5 for each certificate in chain.

So at most 24 bytes for all even remotely realistic-sounding
scenarios.


And for all applications where 256-level curves are even remotely
feasible, 24 bytes is insignificant.


-Ilari