Reward Sharing for Mixnets

We present a reward sharing scheme for incentivized network privacy infrastructures such as the Nym mixnet. Given a bootstrapping reserve and a bandwidth pricing mechanism, our model enables a decentralized, economically sustainable mixnet that can scale, as increased usage translates into fees that allow the mixnet to grow to meet demand. Our scheme periodically selects mix nodes to mix packets proportionally to their reputation, which signals the confidence of stakeholders in the node’s reliability and performance. Selected mix nodes are then rewarded proportionally to their reputation and performance, and share their rewards with the stakeholders supporting them. We prove the properties of our scheme with a game-theoretic analysis, showing that the equilibria promote decentralization and mixnet performance. We further evaluate the scheme empirically via simulations that consider non-ideal conditions and show that the mixnet can be viable under realistic assumptions.