[Cython] Hash-based vtables

[Dag Sverre Seljebotn]

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


>
>Stefan
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