[Cython] Hash-based vtables

[mark florisson]

On 6 June 2012 10:11, Dag Sverre Seljebotn <d.s.seljebotn at astro.uio.no> wrote:
>
>
> Stefan Behnel <stefan_ml at behnel.de> wrote:
>
>>mark florisson, 05.06.2012 22:33:
>>> It doesn't even necessarily have to be about running user code, a
>>user
>>> could craft data input which causes such a situation. For instance,
>>> let's say we have a just-in-time specializer which specializes a
>>> function for the runtime input types, and the types depend on the
>>user
>>> input. For instance, if we write a web application we can post arrays
>>> to described by a custom dtype, which draws pictures in some weird
>>way
>>> for us. We can get it to specialize pretty much any array type, so
>>> that gives us a good opportunity to find collisions.
>>
>>Yes, and the bad thing is that a very high probability of having no
>>collisions even in combination with the need for a huge amount of brute
>>force work to find one is not enough. An attacker (or otherwise
>>interested
>>user) may just be lucky, and given how low in the application stack
>>this
>>will be used, such a bit of luck may have massive consequences.
>
> Following that line of argument, I guess you keep your money in a mattress then? Our modern world is built around the assumption that people don't get *that* lucky.
>
> (I agree though that 64 bits is not enough for the security usecase! I'm just saying that 160 or 256 bits would be.)
>
> Dag
>

I think we're arguing different things. You agree to the security
problem, but Stefan was still emphasizing his old point.

>>
>>Stefan
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>
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