On Wednesday 23 January 2008 00:15, Michael Rogers wrote: > Matthew Toseland wrote: > > How valuable are negative samples? If you are directly connected to the > > originator, you will *never* get a negative sample from it (assuming you can > > unambiguously identify the requests of interest). > > The target location and nearest location of a negative sample could > reveal a lot. If nearestLoc==prevLoc then dist(originator,target) >= > dist(prevLoc,target). Each sample gives you a range of possible > originator locations, and if you get a series of linkable samples you > can intersect the ranges. > > Example: a peer at location 0.3 sends you an interesting request with > target==0.7 and nearestLoc==prevLoc, so dist(originator,0.7) >= > dist(0.3,0.7), so the originator's between 0.1 and 0.3. Then the same > peer sends you another interesting request with target==0.9 and > nearestLoc==prevLoc, so dist(originator,0.9) >= dist(0.3,0.9), so the > originator's between 0.3 and 0.5. Your peer must be the originator.
nearestLoc == prevLoc implies HTL = 10. However, the attack works without nearestLoc == prevLoc. If we get a request with target=0.7 and nearestLoc = 0.3, we know that the originator is no closer to 0.7 than 0.3 is, i.e. dist(originator, 0.7) >= dist(0.3,0.7). If we get another sample, we can intersect the two ranges. > > Cheers, > Michael -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 189 bytes Desc: not available URL: <https://emu.freenetproject.org/pipermail/devl/attachments/20080130/57aea470/attachment.pgp>
