On the Use of Optimal Stopping Theory for Secret Sharing Scheme Update

On the Use of Optimal Stopping Theory for Secret Sharing Scheme Update

Constantinos Delakouridis (Athens University of Economics and Business, Greece) and Leonidas Kazatzopoulos (Athens University of Economics and Business, Greece)
Copyright: © 2013 |Pages: 20
DOI: 10.4018/978-1-4666-4038-2.ch015


The location privacy issue has been addressed thoroughly so far. Cryptographic techniques, k-anonymity-based approaches, spatial obfuscation methods, mix-zones, pseudonyms, and dummy location signals have been proposed to enhance location privacy. In this chapter, the authors propose an approach, called STS (Share The Secret) that segments and distributes the location information to various, non-trusted, entities from where it will be reachable by authenticated location services. This secret sharing approach prevents location information disclosure even in situation where there is a direct observation of the target. The proposed approach facilitates end-users or location-based services to classify flexible privacy levels for different contexts of operation. The authors provide the optimal thresholds to alter the privacy policy levels when there is a need for relaxing or strengthening the required privacy. Additionally, they discuss the robustness of the proposed approach against various adversary models. Finally, the authors evaluate the approach in terms of computational and energy efficiency, using real mobile applications and location update scenarios over a cloud infrastructure, which is used to support storage and computational tasks.
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Prior Work

Several approaches that enable location privacy focus on the secrecy of Medium Access Control (MAC) identifiers or IP-layer address. On the MAC layer, the problem of interface identifiers is discussed in (Gruteser & Grunwald, 2003) that uniquely identify each client, allowing tracking of her location over time. The authors in (Gruteser & Grunwald, 2003) introduce a location privacy scheme through the frequent disposal of a client's interface identifier. In the IP layer, Mobile IP (Fasbender et al., 1996b) implicitly addresses location privacy by associating two different IPs to the same subject (e.g., mobile user); (1) the static one, corresponding to the home network of the user, and (2) the dynamic one, corresponding to the current access network of the user. The Non-Disclosure Method (Fasbender et al., 1996a) considers the existence of independent, security (software) agents that are distributed on the IP network. Each security agent holds a pair of keys and forwards messages in an encrypted format. The sender routes a message to a receiver through the path determined by the security agents. Moreover, the Mist System (Al-Muhtadi et al., 2002) handles the problem of routing a message though a mobile network by keeping the sender’s location private from intermediate routers, the receiver and possible eavesdroppers. The Mist System consists of several routers ordered in a hierarchical structure. Specifically, portal routers are aware of the location of the mobile user without knowing the identity of the user, while the lighthouse routers are aware of the user’s identity without knowing her/his exact location.

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