This project builds peer-to-peer systems in which peers are motivated to honestly contribute to the system, yet remain anonymous. Anonymous electronic cash (e-cash) is used as a tracking mechanism to allow for accountability without sacrificing privacy.
E-cash matches the untraceability properties of physical coins: the same bank is responsible for dispensing e-cash to buyers, and for later accepting it for deposit from sellers, and yet it cannot trace how buyers spent their money.
As a result, e-cash is ideally suited for serving as a currency in p2p systems: privacy is a key feature of many p2p applications, such as onion routing and shared backup.
This project combines systems-building and cryptography work. Our starting point is compact e-cash, a recent invention of one of the PIs, which improves upon the time and space requirements of previous schemes. In addition, primitives that allow sellers to quickly prove properties of data that they offer for sale, without revealing the data itself are being developed.
These cryptographic innovations are being deployed in real distributed systems, including the e-cash bank and p2p applications such as onion routing, shared downloads, data backup, and distributed computation. Innovations in these systems surround the development of contracts that define the interactions of peers in these systems. Contracts ensure that buyers and sellers act honestly.
This project advances our understanding of distributed system with autonomous members. These systems require incentives for peers to render services, yet these incentives must be provided without compromising participant privacy.
