Cloaking Area Research Articles

A hierarchical distributed trusted location service achieving location k-anonymity against the global observer

As widely known in the literature, location-based services can seriously threaten users’ privacy. Privacy-aware location-based services can be obtained by protecting the user’s identity, so that queries cannot be linked with users. A way to do this is to place a trusted third party, called Location Trusted Service, between the user and the service provider, with the role of mediating the queries coming from the users and proxying them to the provider. Before proxying the query, the Location Trusted Service builds a cloaking area that includes a sufficient number of users such that it can represent an anonymity set. This way, the identity of the user is protected against an untrusted service provider. Unfortunately, in wide-area scenarios, a centralized location-trusted service might represent a serious threat to security and privacy because the service represents a single point of failure that manages very critical and massive information. Moreover, privacy protection also against a global adversary capable to monitor the whole traffic, would result in an excessive amount of cover traffic in the network (being cover traffic necessary in this threat model).To overcome the above limitations we propose a hierarchical Location Trusted Service, whose implementation benefits from the edge–cloud paradigm. In our proposal, the territory is organized in hierarchical zones possibly managed by different autonomous organizations. Organizations that manage higher zones are involved when lower-level organizations are not able to satisfy the requests of the users. As only the lowest-level services manage exact location data, while the higher ones operate only on aggregate values, the risk associated with the single point of failure of the centralized solution is drastically reduced. Moreover, leveraging the edge–cloud implementation of the system, network traffic is better confined to the edge of the network, making the protection against the global observer feasible.A nice feature of our method is that it is parametric with respect to any existing cloaking area construction technique. However, as our method, for non-local queries, operates on aggregate data, a certain degree of approximation is introduced. To validate our proposal, we conducted an experimental campaign on a real-life map by applying our method on top of well-known cloaking area construction technique called Casper. The results turned out to be positive. For a wide range of sizes of the anonymity set, the approximation (expressed by the metric called effectiveness) is less than 10%. On the other hand, concerning the network performance, we have observed an improvement in latency and throughput ranging from 20% to 170% (depending on the size of the anonymity set). In the highest density distribution, we achieve a 66% saving in overall (non-local) traffic compared to the centralized approach.

Drone Helps Privacy: Sky Caching Assisted $k$-Anonymity in Spatial Querying

As wireless and mobile devices are prevalent and resource-rich, users can frequently query point-of-interests and enjoy diverse location-based services (LBSs) in infrastructure-based wireless networks. However, users often trade their location privacy with services by sharing their location information with an LBS server, without knowing that the server can fully be trusted. In this article, we propose a sky caching-aided spatial querying scheme with the support of a flying drone. The basic idea is that both the user and its drone collaboratively generate a set of dummy locations to hide the current location of the user from the server. We also propose cache admission control techniques to efficiently cache the queried results to minimize the number of duplicated cached copies. The location privacy is analyzed and measured in terms of the location obfuscation and the size of the convex hull area that consists of dummy locations resided within the cloaking areas of user and drone. We conduct extensive simulation experiments using the OMNeT++ for performance evaluation and comparison. The simulation results show that the proposed approach can reduce the number of queries sent to the server, extend the cloaking area, and improve the location privacy of users significantly.

A trusted de-swinging k-anonymity scheme for location privacy protection

K-anonymity has been gaining widespread attention as one of the most widely used technologies to protect location privacy. Nevertheless, there are still some threats such as behavior deception and service swing, since utilizing distributed k-anonymity technology to construct an anonymous domain. More specifically, the coordinate of the honest node will be a leak if the malicious nodes submit wrong locations coordinate to take part in the domain construction process. Worse still, owing to service swing, the attacker increases the reputation illegally to deceive honest nodes again. To overcome those drawbacks, we propose a trusted de-swinging k-anonymity scheme for location privacy protection. Primarily, we introduce a de-swinging reputation evaluation method (DREM), which designs a penalty factor to curb swinging behavior. This method calculates the reputation from entity honesty degree, location information entropy, and service swing degree. Besides, based on our proposed DREM, a credible cloaking area is constructed to protect the location privacy of the requester. In the area, nodes can choose some nodes with a high reputation for completing the construction process of the anonymous domain. Finally, we design reputation contracts to calculate credit automatically based on smart contracts. The security analysis and simulation results indicate that our proposed scheme effectively resists malicious attacks, curbs the service swing, and encourages nodes to participate honestly in the construction of cloaking areas.

Joint obfuscation of location and its semantic information for privacy protection

Location-based social networks (LBSNs) such as Foursquare and Facebook enable users to share with each other, their (geographical) locations together with the semantic information associated with their locations. The semantic information captures the type of a location and is usually represented by a semantic tag like “restaurant”, “museum”, “school”, etc. Semantic tag sharing increases the threat to users’ location privacy (which is already at risk because of location sharing) and it also puts users’ semantic location privacy at risk. The existing solution to protect the location privacy and the semantic location privacy of users in such LBSNs is to obfuscate the location and the semantic tag independently of each other in a so called disjoint obfuscation approach. Thus, in this approach, the semantic tag is obfuscated i.e., replaced by a more general tag. Also, the location is obfuscated i.e., replaced by a generalized area (called the cloaking area) made of the actual location and some of its nearby locations. However, since in this approach the location obfuscation is performed in a semantic-oblivious manner, an adversary can still increase his chance to infer the actual location and the actual semantic tag by filtering out the locations in the cloaking area that are not semantically compatible with the obfuscated semantic tag. In this work, we address this issue by proposing a joint obfuscation approach in which the location obfuscation is performed based on the result of the semantic tag obfuscation. We also provide a formal framework for evaluation and comparison of our joint approach with the disjoint approach. By running an experimental evaluation on a dataset of real-world user traces collected from six different cities, we show that in almost all cases (i.e., in different cities and with different obfuscation parameters), the joint approach outperforms the disjoint approach in terms of location privacy protection and the semantic location privacy protection. Based on the evaluation results, we also discuss how different obfuscation parameters and the choice of the city can affect the performance of the obfuscation approaches. In particular, we show how changing these parameters can improve the performance of the joint approach.

Blockchain-Based Data Management and Edge-Assisted Trusted Cloaking Area Construction for Location Privacy Protection in Vehicular Networks

With the tremendous pervasion of location-based services (LBSs) in vehicular networks, the location privacy of vehicles has become an utmost concern. K-anonymity is one of the most popular privacy protection solutions, in which the real location of the request vehicle (RV) can be covered by a cloaking area including the location of ${k}$ –1 cooperative vehicles (CVs). However, K-anonymity assumes all CVs are always honest and thus offering opportunities for dishonest CVs to provide false location information. To combat such threats, we propose a trusted cloaking area construction (TCAC) scheme based on the trust mechanism to protect the location privacy of vehicles. In this article, the trust value is not only used to identify dishonest CVs, but also utilized to decide the LBS request of RV. A low trust value will make the LBS request be rejected due to dishonest and selfish cooperative behaviors when the RV has played the role of CV. To deal with the massive trust requirements caused by frequent vehicle movement, edge computing is employed to assist trust value evaluation. Moreover, traditional central and distributed trust data management may be unsuitable for vehicular networks. We also propose a blockchain-based trust data management method by combining vehicular regions partition, so as to rapidly evaluate trust value during the cloaking area construction. The security analysis and simulation results indicate that our proposed scheme is resilient to suppress dishonest CVs, inspire selfish CVs, and protect the location privacy of vehicles effectively, whereas the required computation time and communication cost are both limited.

Optical Illusion Design Based on Four Convex Lenses System and Cloaking Area Characterization

A set up of optical illusion based on 4f system and characterization of cloaking area have been carried out. The cloaking area is an area where the object is placed on the area as if it disappears from view; the set-up of cloaking area is located at the top of the third lens. The distance between the lens and the cloaking, which is generated from 4f system, depends on the size of the focal point and the size of the lens used. The larger the focal point of the lens used the wider the distance between the lenses and the larger the size of the diameter of the lens, the cloaking range will be increasingly wide, and vice versa. From the experimental results that we obtained that the cloaking area for set up using FL (focusing lens) 100, 50, 50 and 100 mm with a diameter of 3.6 cm lens is ± 2 cm, whereas for the set up using lens FL 150, 100, 100 and 150 mm with lens diameter 2.54 cm is ± 1 cm.

Secure Cloaking Area Based on User Profile Similarity

Secure Cloaking Area Based on User Profile Similarity

Seismic Surface Wave Cloaking by Acoustic Wave Refraction

Recently two seismic cloaking methods of earthquake engineering have been suggested. One is the seismic wave deflection method that makes the seismic wave bend away and the other is the shadow zone method that makes an area that seismic waves cannot pass through. It is called as seismic cloaking. The fundamental principles of the seismic cloaking by variable refractive index were explained. A two-dimensional cylindrical model which was composed of 40 layers of different density and modulus was tested by numerical simulation. The center region of the model to be protected is called 'cloaked area' and the outer region of it to deflect the incoming wave is called 'cloaking area' or 'cloak area.' As the incoming surface wave is approaching to the cloaking area, the refractive index is decreasing and, therefore, the velocity and impedance are increasing. Then, the wave bends away the cloaked area instead of passing it. Three cases are tested depending on the comparison between the seismic wavelength and the diameter of the cloaked region. The advantage and disadvantage of the method were compared with conventional earthquake engineering method. Some practical requirements for realization in fields were discussed.

Distributed external cloak without embedded antiobjects

We propose a distributed external cloak without embedded antiobjects, which contains tunable windows and a cloaking area. It consists of closed and standalone systems whose positions and parameters can be separately controlled by the design purpose and folded geometry. Such an external cloak does not rely on either cloaked material or the concept of the antiobject [Phys. Rev. Lett. 102, 093901 (2009)] in the complementary material, and can thus be kept unchanged when different objects are considered. The object lies outside the cloak and is not blinded in terms of multiple open windows desired by specific designs. Such a distributed cloak enables us to conceal arbitrary objects of varying shape in center areas, which may exceed the inner boundary of a perfect closed cloak.