Attrition Defenses for a Peer-to-Peer Digital Preservation System
  In peer-to-peer systems, attrition attacks include both traditional, network-level denial of service attacks as well as application-level attacks in which malign peers conspire to waste loyal peers' resources. We describe several defenses for LOCKSS, a peer-to-peer digital preservation system, that help ensure that application-level attacks even from powerful adversaries are less effective than simple network-level attacks, and that network-level attacks must be intense, wide-spread, and prolonged to impair the system. 
T.J. Giuli, Petros Maniatis, Mary Baker, David S. H. Rosenthal, Mema   Roussopoulos