A TorPath to TorCoin:

Proof-of-Bandwidth Altcoins for Compensating Relays

Mainak Ghosh, Miles Richardson, Bryan Ford

Yale University

Rob Jansen

U.S. Naval Research Laboratory

7th Workshop on Hot Topics in Privacy Enhancing Technologies (HotPETs 2014)

Abstract

The Tor network relies on volunteer relay operators for relay bandwidth, which may limit its growth and scaling potential. We propose an incentive scheme for Tor relying on two novel concepts. We introduce TorCoin, an “altcoin” that uses the Bitcoin protocol to reward relays for contributing bandwidth. Relays “mine” TorCoins, then sell them for cash on any existing altcoin exchange. To verify that a given TorCoin represents actual bandwidth transferred, we introduce TorPath, a decentralized protocol for forming Tor circuits such that each circuit is privately-addressable but publicly verifiable. Each circuit’s participants may then collectively mine a limited number of TorCoins, in proportion to the end-to-end transmission goodput they measure on that circuit.

This material is based upon work supported by the Defense Advanced Research Agency (DARPA) and SPAWAR Systems Center Pacific, Contract No. N66001-11-C-4018. This work was supported by the Office of Naval Research.