Interesting research on P2P privacy
(summarized by Bruce Schneier
): P2P downloaders naturally self-assemble small communities. "[A] savvy attacker can correctly extract communities more than 85 percent of the time by observing only 0.01 percent of the total users...this information could be used to launch a 'guilt-by-association' attack, where an attacker need only determine the downloading behavior of one user in the community to convincingly argue that all users in the communities are doing the same." The solution? Hide actual downloads in a cloud of random downloads---in other words, become an inverse spammer. Given how often masking real content with randomness is a solution in technological systems, I have to wonder if it's somehow an explanation for junk DNA
in natural systems as well.