Re: CERT vulnerability note VU# 539363 (fwd)

[Miles Sabin <miles () milessabin com>]

Mike Frantzen wrote,
> The problem with a hashed state table is that hash tables are very
> easy to attack.  The use of collision chains (linked lists) would let
> an attack totally blow out the D$ and TLB.  I've make a sun U10
> 440mhz w/ 2MB L2 grind to a halt w/ 5 packets a second after a long
> series of collisions.

Interesting ... the idea being that with knowledge of the hash function 
an attacker could manufacture enough collisions to push the hash table 
to the O(n) worst case?

Couldn't that attack be frustrated by a more sophisticated hash function 
parameterized with a local secret (ie. the attacker would need to know 
the secret as well as the function before they could reliably generate 
collisions)? Or would that make the hash function too computationally 
expensive?

Cheers,


Miles
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