In this paper, we present a very simple and efficient endto-end algorithm to handle wormhole attacks on ad hoc networks. We provide a lower bound on the minimum number of hops on a good route. Any path showing lesser hopcounts is shown to be under attack. Our algorithm requires every node to know its location. With very accurate GPS available, this assumption is not unreasonable. Since our protocol does not require speed or time, we do not need clock synchronization. In the absence of any error

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... in the location, there are no false alarms i.e. no good paths are discarded. We have shown that the effect of error in the location information is negligible. The storage and computation overhead is low. For a path of length l, it takes only O(l) space and time which is less as compared to other end-to-end algorithms like Wang etal [8]. Their algorithm uses O(lm) storage and O(lm 2 ) computation time, where m is the number of packets examined. Since their protocol uses speed to detect wormholes, they assume the clocks to be loosely synchronized.