DogFish: decentralized optimistic game-theoretic FIle SHaring

Abstract

Peer-to-peer (p2p) file sharing accounts for the most uplink bandwidth use in the Internet. Therefore, in the past few decades, many solutions tried to come up with better proposals to increase the social welfare of the participants. Social welfare in such systems are categorized generally as average download time or uplink bandwidth utilization. One of the most influential proposals was the BitTorrent. Yet, soonafter studies showed that BitTorrent has several problems that incentivize selfish users to game the system and hence decrease social welfare. Previous work, unfortunately, did not develop a system that maximizes social welfare in a decentralized manner (without a trusted party getting involved in every exchange), while the proposed strategy and honest piece revelation being the only equilibrium for the rational players. This is what we achieve, by modeling a general class of p2p file sharing systems theoretically, then showing honest piece revelation will help achieve social welfare, and then introducing a new cryptographic primitive, called randomized fair exchange, to instantiate our solution.