3 ms·

Any links to learn more?

• formerly_proven 5y ago
  The average performance of hashtables generally depends on collisions being rare, but if the hashed index is trivially derivable from the key, then an attacker can supply data where everything hashes to the same index, regressing performance to the point that it's a DoS attack. This is why cryptographically secure short-output hash functions like SipHash were developed.
• ddevault 5y ago
  https://en.wikipedia.org/wiki/Collision_attack#Hash_flooding https://en.wikipedia.org/wiki/Collision_attack#Hash_flooding Note that this is only a problem when an attacker can influence your hash table usage, and can be mitigated with hashing functions like siphash. This is not necessary for the majority of hash tables in the wild.