Browsing by Subject "Location Privacy"
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Item Anonymity of the Base-Station in Wireless Sensor Networks(2022-01-01) Ebrahimi, Yousef; Younis, Mohamed; Computer Science and Electrical Engineering; Engineering, ComputerIn a wireless sensor network (WSN), nodes probe their surroundings and send their measurements over multi-hop routes to an in-situ base-station (BS). The BS aggregates the collected data and orchestrates a response either autonomously or through consultation with a command center. Since the BS is crucial to the WSN operation, an adversary might target it to inflict the most damage to the network. Even if the BS is camouflaged, an adversary may locate it by intercepting transmissions and applying traffic analysis. This dissertations opts to increase the anonymity of the BS and conceal its location. Two adversary models are considered, local and global. The former sniffs packet transmission and measures transmission volume given that the BS vicinity often experiences the most packet relaying activities. To counter such a local sniffer, a mechanism is proposed that generates bogus traffic to confound high transmissions volume away from the BS to mislead the adversary. Meanwhile, a global adversary intercepts all transmissions and uses sophisticated traffic analysis models such as Evidence Theory (ET). Using ET, the adversary correlates intercepted transmissions to deduce new evidence of data routes that end at the BS. First, we exploit the complexity of ET as a countermeasure by dynamically increasing the transmission range of nodes to cover more destinations. Second, we manipulate the ET analysis via fake traffic generation in low activity areas to diminish the importance of regions closer to the BS. Scarcity of energy resources is often overlooked in favor of boosting network anonymity. In this dissertations, by analyzing energy consumption patterns, we first propose a novel energy-aware and multi-zone scheme to significantly reduce the overhead of countermeasures on highly overburdened nodes in the BS proximity, and hence significantly improve the WSN lifespan. Then, the multi-zone design is extended by a novel cross-layer technique that exploits transmission range adjustment to confuse the adversary about the data paths. This results in a versatile and effective countermeasure that significantly improves anonymity of the BS without negative implications on the network lifespan. ET only uses spatial aspects of intercepted transmissions; hence we propose an enhanced version of ET (EET) that also utilizes temporal correlation of transmissions to draw further insight about the network. Two countermeasures, namely, Delaying Packets Relaying (DPR) and Assisted Deception (AD), are developed to make the WSN resilient to both ET and EET. DPR imposes buffering delay at each node while AD allows nodes to coordinate and inject timed deceptive packets. Both techniques aim to disturb the time correlation of consecutive transmissions that EET relies on. The attack and countermeasures are validated through simulation experiments.Item Cross-Layer Techniques for Boosting Base-Station Anonymity in Wireless Sensor Networks(2016-01-01) Alsemairi, Sami Saad; Younis, Mohamed; Computer Science and Electrical Engineering; Computer ScienceWireless Sensor Networks (WSNs) provide an effective solution for surveillance and data gathering applications in hostile environments where human presence is infeasible, risky or very costly. Examples of these applications include military reconnaissance, guarding boarders against human trafficking, security surveillance, etc. A WSN is typically composed of a large number of sensor nodes that probe their surrounding and transmit measurements over multi-hop paths to an in-situ Base-Station (BS). The BS not only acts as a sink of all collected sensor data but also provides network management and serves as a gateway to remote commend centers. Such an important role makes the BS a target of adversary attacks that opt to achieve Denial-of-Service (DoS) and nullify the WSN utility to the application. Even if the WSN applies conventional security mechanisms such as authentication and data encryption, the adversary may apply traffic analysis techniques to locate the BS and target it with attacks. This motivates a significant need for boosting BS anonymity to conceal its location. In this dissertations, we address the challenges of BS anonymity and develop a library of techniques to counter the threat of traffic analysis. The focus of our work is on the link and network layers. We first exploit packet combining as a means to vary the traffic density throughout the network. We call this technique combining the data payload of multiple packets (CoDa), where a node groups the payload of multiple incoming data packets into a single packet that is forwarded toward the BS. CoDa cuts on the number of transmissions that constitute evidences for implicating the BS as a destination of all traffic and thus degrades the adversary'sability in conducting effective traffic analysis. Next we develop a novel technique for increasing BS anonymity by establishing a sleep/active schedule among the nodes that are far away from the BS, and increasing the traffic density in selected parts of the network in order to give the impression that the BS is located in the vicinity of the sleeping nodes. We call this technique Adaptive Sampling Rate for increased Anonymity (ASRA). Moreover, we develop three novel techniques based on a hierarchical routing topology. The first, which we call Hierarchical Anonymity-aware Routing Topology (HART), forms clusters and an inter-cluster-head routing topology so that a high traffic volume can be observed in areas away from the BS. The second is a novel cross-layer technique that forms a mesh topology. We call this technique cluster mesh topology to boost BS'sanonymity (CMBA). CMBA opts to establish a routing topology such that the traffic pattern does not implicate any particular node as a sink. The third technique creates multiple mesh-based routing topologies among the cluster-heads (CHs). By applying the closed space-filling curves such as the Moore curve, for forming a mesh, the CHs are offered a number of choices for disseminating aggregated data to the BS through inter-CH paths. Then, the BS forwards the aggregated data as well so that it appears as one of the CH. We call this technique boosting the BS anonymity through multiple mesh-based routing topologies (BAMT). We validate the effectiveness of all anonymity-boosting techniques through simulation and highlight the trade-off between anonymity and overhead.Item Efficient Traffic Morphing Techniques for Boosting Base-station's Location Privacy in Wireless Sensor Networks(2017-01-01) Baroutis, Nikolaos; Younis, Mohamed; Computer Science and Electrical Engineering; Computer ScienceIn recent years, Wireless Sensor Networks (WSNs) have been attracting increased attention from the research and engineering communities. A WSN typically consists of a large population of spatially distributed sensor nodes that cooperatively monitor environmental conditions and report their findings to an in-situ base station (BS). The BS not only collects and analyzes the incoming data, but also interfaces the WSN to a higher authority. The unique role of the BS attracts adversary'sattention since it can be a single point of failure for the WSN. An adversary that seeks to diminish the network utility can apply traffic analysis techniques to locate the BS, and target it with denial of service attacks. In this dissertations, we develop three traffic analysis countermeasures that morph the network'straffic pattern in order to divert the adversary'sattention away from the BS and make the traffic analysis inconclusive. The first two countermeasures use fake sinks (FSs) and deceptive relay nodes, aiming to mimic the traffic pattern of the BS vicinity in multiple areas across the network. The first countermeasure, named, traffic morphing through routing to fake sinks (MoRF), probabilistically selects some nodes to act as deceptive relays to de-correlate packet flows from the data routes by creating redundant traffic toward the fake sinks. The second countermeasure, which we call multiple sinks illusion (MSI), deterministically determines the amount and distribution of deceptive traffic so that the anonymity goal is achieved while the overhead is reduced and evenly split across many nodes. We further develop a novel attack model, named Evidence theory analysis with reduced search space (EARS) that increases the adversary'sconfidence in localizing the BS while significantly reducing the traffic analysis complexity. Additionally, we introduce two novel anonymity metrics. The new attack model and metrics better gauge the effectiveness of a countermeasure in terms of BS protection. Most of the existing countermeasures, including MoRF and MSI, usually expose only some parts of the WSN to the adversary. Such a strategy is deemed a compromise that trades off location privacy and performance. In order to strike a balance in the aforementioned trade-off, we finally present a countermeasure, named, preserve location anonymity through uniform distribution of traffic volume (PLAUDIT) that strives to equalize the traffic density across the network in order to make the BS undistinguishable.