[Draxis]

From what I know of networking (which is not that much, did not do well in the subject at university) most networking protocols are designed to prevent *accidental* imperfections, but there are a lot of possible variations of a single block (say 256Kb) that would all pass the same validation hash. Assuming every single block of a torrent had an associated MD5, to sabotage the theft, you only need to send a differnt block but the block would hash out the same MD5. When the entire file was finished, it would almost certainly fail any check on it, but that is still a few hundred megs that has to be redownloaded, and would only take 1 dodgy block to break again.