The optimality that we prove for our protocol is very strong. Given any routing protocol, we evaluate its efficiency (rate of message delivery) in the ``worst case,'' that is with respect to the worst possible graph and against the worst possible (polynomially bounded) adversarial strategy (subject to the above mentioned connectivity constraints). Using this metric, we show that there does not exist any protocol that can be asymptotically superior (in terms of throughput) to ours in this setting.
We remark that the aim of our paper is to demonstrate via explicit example the feasibility of throughput-efficient authenticated adversarial routing. However, we stress that out protocol is not intended to provide a practical solution, as due to its complexity, no attempt thus far has been made to make the protocol practical by reducing constants or the large (though polynomial) memory requirements per processor.
Our result is related to recent work of Barak, Goldberg and Xiao in 2008 who studied fault localization in networks assuming a private-key trusted setup setting. Our work, in contrast, assumes a public-key PKI setup and aims at not only fault localization, but also transmission optimality. Among other things, our work answers one of the open questions posed in the Barak et. al. paper regarding fault localization on multiple paths. The use of a public-key setting to achieve strong error-correction results in networks was inspired by the work of Micali, Peikert, Sudan and Wilson who showed that classical error-correction against a polynomially-bounded adversary can be achieved with surprisingly high precision. Our work is also related to an interactive coding theorem of Rajagopalan and Schulman who showed that in noisy-edge static-topology networks a constant overhead in communication can also be achieved (provided none of the processors are malicious), thus establishing an optimal-rate routing theorem for static-topology networks.
Finally, our work is closely related and builds upon to the problem of End-To-End Communication in distributed networks, studied by Afek and Gafni, Awebuch, Mansour, and Shavit, and Afek, Awerbuch, Gafni, Mansour, Rosen, and Shavit, though none of these papers consider or ensure correctness in the setting of a malicious adversary controlling the majority of the network.Category / Keywords: public-key cryptography / Network Routing; Error-correction; Fault Localization; Multi-parity Computation in the presence of Dishonest Majority; Communication Complexity; End-to-End Communication Date: received 22 Oct 2008, last revised 3 Jan 2009 Contact author: paulbunn at math ucla edu Available format(s): Postscript (PS) | Compressed Postscript (PS.GZ) | PDF | BibTeX Citation Note: Corrected typos Version: 20090103:233009 (All versions of this report) Discussion forum: Show discussion | Start new discussion