[Python-Dev] Status of the fix for the hash collision vulnerability

martin at v.loewis.de martin at v.loewis.de
Tue Jan 17 09:16:36 CET 2012

>> It doesn't change anything, you will still get collisions.
> That depends right? If the collision is because they all have the same
> hash(), yes. It might be different if it is because the secondary hashing
> (or whatever it's called :-) causes collisions.

But Python deals with the latter case just fine already. The open hashing
approach relies on the dict resizing "enough" to prevent collisions after
the dictionary has grown. Unless somebody can demonstrate a counter example,
I believe this discussion is a red herring.

Plus: if an attacker could craft keys that deliberately cause collisions
because of the dictionary size, they could likely also craft keys in the same
number that collide on actual hash values, bringing us back to the original


More information about the Python-Dev mailing list