[Cython] Hash-based vtables

[Dag Sverre Seljebotn]

On 06/05/2012 09:25 AM, Stefan Behnel wrote:
> Dag Sverre Seljebotn, 04.06.2012 21:44:
>>     This can cause crashes/stack smashes
>>     etc. if there's lower-64bit-of-md5 collisions, but a) the
>>     probability is incredibly small, b) it would only matter in
>>     situations that should cause an AttributeError anyway, c) if we
>>     really care, we can always use an interning-like mechanism to
>>     validate on module loading that its hashes doesn't collide with
>>     other hashes (and raise an exception "Congratulations, you've
>>     discovered a phenomenal md5 collision, get in touch with cython
>>     devs and we'll work around it right away").
>
> I'm not a big fan of such an attitude. If this happens at runtime, it can
> induce any cost from cheap-at-test-time to hugely-expensive-in-production.
> Thinking with my evil hat on, this can potentially be data triggered from
> the outside (e.g. if a JIT compiler is involved at one end), thus possibly
> even leading to a security hole.
>
> We should try to produce software that others can build a business on.

Well, I'd build a business on something that fails with a 5e-7 
probability any day :-) (given that you trust my estimates in the other 
post; I think they were rather conservative myself)

But I'll do benchmarks for 96-bit and 128 bit hash comparisons as soon 
as I can get around to it.

Dag