[tor-dev] Improved circuit-setup protocol [was: Re: Designing and implementing improved circuit-setup protocol [was: GSoC 2011]]

[Ian Goldberg]

On Thu, Apr 07, 2011 at 06:13:45PM -0400, Nick Mathewson wrote:
> Oh!  Also, for a bit of redundancy, I'm thinking that the symmetric
> crypto parts of the improved onion handshakes ought to be with a less
> malleable mode of operation than the counter-mode stuff we do now.

Yes.  Absolute necessity.

> Perhaps we could make use of an all-or-nothing mode of operation like
> LIONESS or biIGE.  (They're both slower than counter mode, but for
> purposes of CREATE cells, I don't think the hit will matter in
> comparison with the cost of the public-key operations.)

A MAC (or a cipher mode that includes integrity like GCM) would be a
good start.

   - Ian