First I want to thank everyone for posting such good papers on this mailing list - it has given me lots of good reading material! Now I have a chance to give back to the community...I've been researching the problem of web censorship and how to design a system to get around it. Initially I wanted to build a P2P mixnet so that the users would also have anonymity. It turns out that due to various attacks that it isnt possible to build a "totally decentralized" P2P network - instead it looks more like a star where one server manages many proxy nodes. This is one example where p2p just isnt possible (I know, blasphemy on this mailing list!). Zooko encouraged me to write down my findings, and this is what I came up with: Not Too Few, Not Too Many: Enforcing Minimum Network Knowledge In Distributed Systems http://www.peek-a-booty.org/pbhtml/modules.php?name=Downloads&d_op=getit&lid= 12 Comments are welcome. Abstract: Some distributed systems require that each node know as few other nodes as possible while still maintaining connectivity to the system. We define this state as "minimum network knowledge". In particular, this is a requirement for Internet censorship circumvention systems. We describe the constraints on such systems: 1) the Sybil attack, 2) the man-in-the-middle attack, and 3) the spidering attack. The resulting design requirements are thus: 1) An address receiver must discover addresses such that the network Node Arrival Rate <= Node Discovery Rate <= Node Departure Rate, 2) There must be a single centralized trusted address provider, 3) The address provider must uniquely identify address receivers, and 4) The discovery mechanism must involve reverse Turing tests (A.K.A. CAPTCHAs). The "minimum network knowledge" requirement also puts limits on the type of routing the network can perform. We describe a new attack, called the Boomerang attack, where it is possible to discover all the nodes in a network if the network uses mixnet routing. Two other well-known attacks limit the types of routing mechanisms: the distributed denial-of-service attack and the untraceable cracker attack. We describe three routing mechanisms that fit within the constraints: single, double, and triple-hop routing. Single-hop is a basic proxy setup, double-hop routing protects the user's data from snooping proxies, and triple hop hides proxy addresses from trusted exit nodes. _______________________________________________ p2p-hackers mailing list p2p-hackers@zgp.org http://zgp.org/mailman/listinfo/p2p-hackers _______________________________________________ Here is a web page listing P2P Conferences: http://www.neurogrid.net/twiki/bin/view/Main/PeerToPeerConferences ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> ______________________________________________________________ ICBM: 48.07078, 11.61144 http://www.leitl.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE http://moleculardevices.org http://nanomachines.net [demime 1.01d removed an attachment of type application/pgp-signature]