Considering a scenario of anonymous data transfer between seller and buyer using proxies. If we consider that there are three proxies that are being selected by the buyer to obtain data from different sellers (like in emule), how can we make sure that these proxies do not collude with each other to obtain the copy that is being requested by buyer?
For example, if we use onion routing, then in this case, each of three proxies will have plain-text data at the end, and this plain-text data would be transferred to the buyer. What mechanism should we employ that will prevent the three proxies to collude? If they combine the files, they will get the copy of the same file being requested by buyer.
Thus as a solution, if we use end-to-end encryption, will the buyer and seller remain anonymous to each other?