On Thu, 2016-12-15 at 15:57 +0800, Herbert Xu wrote:
> Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> > 
> > Siphash needs a random secret key, yes. The point is that the hash
> > function remains secure so long as the secret key is kept secret.
> > Other functions can't make the same guarantee, and so nervous
> > periodic
> > key rotation is necessary, but in most cases nothing is done, and so
> > things just leak over time.
> 
> Actually those users that use rhashtable now have a much more
> sophisticated defence against these attacks, dyanmic rehashing
> when bucket length exceeds a preset limit.
> 
> Cheers,

Key independent collisions won't be mitigated by picking a new secret.

A simple solution with clear security properties is ideal.