Multiple projects currently focus on on-chain privacy but at network level, Ethereum utilizes broadcasting of messages in a P2P setting which is known to have inferior privacy-guarantees compared to mixnets. Beyond the core layer, dapps running on top of Ethereum or users interfacing these dapps and communicating with one another need a go-to protocol that allows them to exchange data without leaking private metadata that allows for de-anonymizing them while using a dapp.
In this talk we highlight some attacks that collect network metadata in order to de-anonymize senders of a transaction. We then show how a mixnet like HOPR can be used to establish network-level metadata privacy. HOPR is a mixnet that allows participating nodes to earn ETH for relaying messages and thereby provide privacy. As HOPR requires cooperation of downstream nodes to unlock a payment, traditional payment channels would lead to race conditions that allow relayers to exploit the network. We will present an alternative to common payment channel implementations, building on commutative properties of elliptic curves for efficiently closing payment channels.
