Hi, >> Can you rephrase whether you want info about DHT systems that are >> related to some kind of mix system (e.g. GNUnet), or whether you >> simply want to know about common DHT systems. If the latter, what >> kind of attacks are you after? Eclipse? > > My knowledge of the field is pretty spotty in general as I've never > paid much attention up until now -- mostly I know about how people > have built DHTs in non-hostile environments. I'm close enough to > starting from scratch that I don't know yet what I don't know.
OK, so I'll just add to what's been written so far. * Most DHTs are indeed intended for a non-hostile environment and allow users to freely place information in the DHT. This means that data items can be easily eclipsed from the network by abusing the DHT's principle of storing an item on the node with the ID that is closest to the item's own ID. Most concepts support replica. * The only DHT type that really has seen wide deployment seems to be Kademlia, most notably in aMule/eMule and some bot networks. Steiner et al. showed by example that Eclipse attacks against data items are easy ("Conducting and optimizing Eclipse attacks in the Kad P2P network"). * The aMule developers reacted to that attack by restricting routing tables. Kohen/Leske et al. showed that this can be easily circumvented by introducing chains of attackers that cooperate in a particular fashion to redirect queries and let Kad run into a timeout. * We have been active in Kad research for a little while, too. We found that while Eclipse attacks against data items are easy, they are much much harder against active nodes. I.e. Kad is designed to keep long-running nodes as long in the routing tables as possible, and to spread this knowledge widely in the network. This makes it very hard for an attacker to reroute traffic intended for a victim. However, given a very strong attacker (1000s of nodes), this should become possible again. It is one of the disruptive DoS methods. * The most interesting work that I know of is GNUnet: www.gnunet.org. They employ a DHT called R5N that combines recursive Kad-style routing with an initial random walk to evade the above attacker. GNUnet's problem is that there are not enough developers to get the network to a reasonable size, but the underlying technology is interesting. GNUnet also has a SDSI/SPKI-style DNS replacement called GADS. Christian Grothoff is the main developer and also at TUM (that's how I know him) - he recently gave a talk on PRISM and GNUnet: https://www.gnunet.org/internetistschuld There is a host of older literature, too - P2P research, however, has become a cold topic. Although I expect that it will see a revival in the face of surveillance. Ralph -- Ralph Holz I8 - Network Architectures and Services Technische Universität München http://www.net.in.tum.de/de/mitarbeiter/holz/ Phone +49.89.289.18043 PGP: A805 D19C E23E 6BBB E0C4 86DC 520E 0C83 69B0 03EF _______________________________________________ The cryptography mailing list firstname.lastname@example.org http://www.metzdowd.com/mailman/listinfo/cryptography