## 8 Future Work and Discussion  
In this section, we highlight a couple of aspects of **Discard** that can be improved to achieve better performance guarantees. Since we assume that nodes were deployed in groups, we were able to save on communication, computation and storage costs dramatically over earlier work, as we do not need to generate location claims for every interaction among nodes. There is another vector of information that may be utilized to further reduce these costs. If we assume that there is a notion of time synchronization among the sensors, we may utilize this vector to determine the legitimacy of nodes, which may obviate the need for some verification messages, leading to further energy savings. Verification may be required only when both the time and space information for a node are amiss. An additional improvement that may lead to further communication cost savings is: before exchanging the neighborhood or duplicate caches, nodes might consider computing the checksum and, if different, decide to exchange and merge the caches. However, this necessitates storing the caches in a specific order and introduces computational costs. In addition to some of the questions that were raised in Section 6.5, observe that **Discard**, like most other replica detection schemes, is susceptible to a denial of service attack by the adversary. However, **Discard** is more resilient to this attack than existing schemes outlined in Section 2 of prior work. First, observe that our scheme places the burden of collecting the evidence signatures from the verifier nodes on the nodes seeking authentication. Suppose an adversary were to deploy duplicate nodes, claim falsified locations and contact the verifier nodes. While this does deplete the energy of the verifiers who are distributed randomly across time and the home zone, it does so much more rapidly on the duplicate nodes themselves. Verifiers do not process any verification messages unless they are indeed chosen to be verifiers by the base station random seed. Hence, the denial of service attack that the adversary has launched is expected to be short-lived. However, a more satisfactory solution would be desirable. On another note, observe that when a node \(n\) determines the IDs of the \(v\) verifier nodes from its home zone to acquire verification evidence, it is possible (with a small probability) that the node IDs generated, using the random seed broadcast by the base station, are themselves nodes deployed outside the home zone. In this case, node \(n\) will not receive the response it expects. In this case, node \(n\) collects the signatures it receives and is forced to wait another time period to contact more verifiers to reach the threshold of \(v\) signatures to be accepted into the network before participating in network activities. In the future, we would like to test **Disccard**'s capabilities on diverse topologies with varying deployment accuracy. While, theoretically, we expect our epidemic techniques to yield similar results, it would be interesting to observe practical consequences of diverse topologies and poor deployment accuracy. Our motivation to design **Disccard** in its present form was to keep it simple and lead to easy implementation. Furthermore, **Disccard** requires very few guarantees from the underlying communication platform, which is not true in some of the prior schemes. Some other fundamental exploratory questions to consider, at the expense of adding complexity, are: the choice of peer sensor nodes and the choice of verifier nodes. We would like to study the potential impact of the \"power of two random choices\" [48], a simple, yet powerful construct that shows that a small amount of choice can yield significant performance improvements in a randomized algorithm.