Re: Time Invariant String Comparison

[Rob Kendrick <rjek@...>]

On Thu, Jan 16, 2014 at 06:39:28AM -0600, Paige DePol wrote:
> On Jan 16, 2014, at 6:30 AM, Elias Barrionovo <elias.tandel@gmail.com> wrote:
> 
> > On Jan 16, 2014 9:55 AM, "Daniel Silverstone" <dsilvers@digital-scurf.org> wrote:
> > > Lua's strings are interned and hashed.  As a result, string comparison for
> > > equality is pretty much constant time :)
> > 
> > Unless it's Lua >= 5.2 and the password is really large, like >32 bytes large. But this can be changed at compile time.
> 
> As for the password attack, wouldn't just adding a tiny random delay to each request negate such a problem?

Depends on the quality of your RNG.  If you use /dev/random then you've
just changed the attack from a timing attack on passwords to an entropy
depletion attack.

B.