[freenet-dev] Why getting rid of HTL is bad was Re: Vulnerability in inserting the manifest before finishing

[Michael Rogers]

Matthew Toseland wrote:
>> We're using a reliable transport between nodes, so the only things that
>> should cause a timeout are overloaded, crashed or faulty nodes. 
> 
> Not true. Very long paths can also cause this.

Ah, good point.

>> The closest-location-so-far tells an attacker something about the path a
>> request has followed - among other things, it allows the attacker to
>> rule out certain nodes the request definitely hasn't passed through. But
>> how would we quantify that in terms of the size of the initiator's
>> anonymity set or the probability that a given node is the initiator, for
>> example?
> 
> Well, how does the attacker rule out previous nodes?

Any node that's closer to the target than the closest-location-so-far
has never seen the request, otherwise the closest-location-so-far
wouldn't have its current value.

> How many can he rule out?

That's kind of the point: I can't work out how to quantify how much the
attacker can learn, which means it's possible that a clever attacker can
learn a lot. Whereas with a weighted coin (despite its other
disadvantages) at least we know how much the attacker can learn.

Cheers,
Michael