Economic Measures to Resist Attacks on a Peer-to-Peer Network

Peer-to-peer systems in which the peers are truly autonomous have valuable properties, including resistance to certain forms of organizational failure and legal attack. Unfortunately, they can be vulnerable to malign peers. In the context of the LOCKSS system, a peer-to-peer digital preservation system for e-journals, we describe a set of techniques that enable a large population of autonomous peers to resist attack by a substantial minority of malign peers endowed with unlimited computational resources. LOCKSS peers are able to detect attacks and alert the community of peer operators before damage becomes irreversible. These techniques include rate limitation and making peers “pay” certain costs by demanding proofs of effort from them.