We propose the first practical solution to the long-routing layer attacks, and provides good performance in bestanding problem of secure wireless routing in the presence nign conditions. Sprout is a source-routed, link-state, multiof colluding attackers. Our secure routing protocol, Sprout ' path routing protocol. In contrast with previous work Sprout continuously tries new routes to the destination. Routes are ... r . . c probabilistically generated, with complete disregard for

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... routes probabilistically, focusing in the first stage mance metrics. This makes Sprout uniquely resilient to attack: it on diversity, rather than predicted performance. This makes cannot be tempted by shortcuts. In order to avoid compromised it more resilient than previously proposed routing algorithms, routes, and to ensure good overall performance, the quality to a wide variety of attacks. The obvious drawback of this of each active route is monitored by means of signed end-approach is that many of the generated paths are of poor qualto-end acknowledgments. The amount of traffic sent on each route is adjusted accordingly. Sprout effectively mitigates the bty, pan may cion alttaes. To as , a perfomace vast majority of known routing layer attacks, even when under based path selection algorithm is used as a second stage, which assault from a large number of colluding attackers. Experiments assigns a probability to each generated route depending on its on our 31-node testbed demonstrates the real-world performance measured reliability and end-to-end delay. Reliable routes with of Sprout in terms of packet delivery ratio, round-trip times and short round-trip times carry the majority of packets, while a TCP throughput. Our security analysis and simulation results . o show that Sprout is able to quickly find working paths in fraction of packets are sent along other routes, to maintain networks of hundreds of nodes and dozens or more attackers. diversity. With every new route sampled, the probability of For example, in a network of 200 nodes and an astounding 64 finding a good one increases rapidly. attackers, Sprout, on average, found a successful route within The primary contributions of this paper are as follows: less than 10 attempts. Yet, in benign settings, Sprout provides TCP throughput within 15% of the shortest path throughput. * A secure link-state dissemination protocol that minimizes Overall, Sprout consistently delivers high, reliable performance t tofcfae l inks avalable tocolldnattackes in benign as well as hostile environments.2 the types of fake links available to colluding attackers. . A probabilistic route generation algorithm that quickly