3 ms·
What if you use random noise from a Cauchy distribution? It (interestingly enough) has no mean, so the amount of time the attacker thinks she has to subtract fr
by semi-extrinsic 12y ago
What if you use random noise from a Cauchy distribution? It (interestingly enough) has no mean, so the amount of time the attacker thinks she has to subtract from her average depends on the number of samples that she takes, and does not converge as she increases the number of samples.
- dcauchy 12y agoAttacker uses the median
- semi-extrinsic 12y agoHmm. How does she know to use the median? What if I alternate between a Cauchy distribution and a lognormal (having different mean and median)? (Very apropos nick, by the way)
- mikeash 12y agoI'm not particularly familiar with this so the odds of the following being correct are not terribly great.... As far as I can tell, the interesting properties of the Cauchy distribution come from the "fat tail," which means that large numbers are relatively more likely than if you used, for example, a gaussian distribution. This is going to cause problems when applying it to this case because you can't sleep arbitrarily long. There will have to be some sort of ceiling on it, and I think that will bring the behavior back into a realm where the attacker can make use of it. As to your question in your other reply about how the attacker will know to use the median instead of the mean, is there any distribution where using the median wouldn't work? If not, the attacker could just use the median as a matter of course. The idea posted here is interesting: https://news.ycombinator.com/item?id=9264760 https://news.ycombinator.com/item?id=9264760 Basically, have the artificial delay be unpredictable to an attacker, but constant for any given input. You'd still have to watch out for inputs which are computationally equivalent but not bytewise equal, but perhaps that can be managed.