[grsec] Hyperthreading and Xeon x86_64's

[coderman]

On 12/12/05, coderman <coderman at gmail.com> wrote:
> ...
> [* it is possible to make AES resistant to this attack in software,
> but greatly reduces the efficiency / throughput, probably too much for
> practical use]

just encountered the following which may be of interest to those
concerned about timing based side channels in cipher operations:

http://eprint.iacr.org/2005/368

"we propose a generic source-to-source transformation that produces
programs provably secure against control-flow side channel attacks...
it has a performance overhead of at most 5X and a stack space overhead
of at most 2X. Our approach to side channel security is practical,
generally applicable, and provably secure against an interesting class
of side channel attacks."

5x overhead isn't too bad considering.  perhaps this could be an
option for grsecurity in software based crypto operations for the
linux crypto API?