Cloaking locations for anonymous location based services: a hybrid approach

Abstract

Abstract. An important privacy issue in Location Based Services(LBS) is to hide a user's identity while still provide quality location based services. Previous work has addressed the problem of locational K-anonymity either based on centralized or decentralized schemes. However, a centralized scheme relies on an anonymizing server(AS) for location cloaking, which may become the performance bottleneck when there are large number of clients. More importantly, holding information in a centralized place is more vulnerable to malicious attacks. A decentralized scheme depends on peer communication to cloak locations and is more scalable. However, it may pose too much computation and communication overhead to the clients. The service fulfillment rate may also be unsatisfied especially when there are not enough peers nearby. This paper proposes a new hybrid framework called HiSC that balances the load between the AS and mobile clients. HiSC partitions the space into base cells and a mobile client claims a surrounding area consisting of base cells. The number of mobile clients in the surrounding cells is kept and updated at both client and AS sides. A mobile client can either request cloaking service from the centralized AS or use a peer-to-peer approach for spatial cloaking based on personalized privacy, response time, and service quality requirements. HiSC can elegantly distribute the work load between the AS and the mobile clients by tuning one system parameter base cell size and two client parameters -surrounding cell size and tolerance count. By integrating salient features of two schemes, HiSC successfully preserves query anonymity and provides more scalable and consistent service. Both the AS and the clients can enjoy much less work load. Additionally, we propose a simple yet effective RRS(random range shifting)algorithm to prevent possible privacy leakage that would exist in the original P2P approach. Our experiments show that HiSC can elegantly balance the work load based on privacy requirements and client distribution. HiSC provides close to optimal service quality. Meanwhile, it reduces the response time by more than an order of magnitude from both the P2P scheme and the centralized scheme when anonymity level(value of K) or number of clients is large. It also reduces the update message cost of the AS by nearly 6 times and the peer searching message cost of the clients by more than an order of magnitude.

Assignment as a location-based service in outsourced databases

“…K-anonymity protects the location information of a user by hiding it among other K-1 user locations (which may include dummies). In the literature, many approaches based on cloaking, K-anonymity, and dummies have been proposed to reduce the possibility of identifying a user's location [4,5,24,[26][27][28][29].…”

“…Anonymizers increase the implementation and maintenance costs; additionally, they may become a potential point of failure or security breach. Instead of using an anonymizer, queries could be anonymized among the users in a decentralized manner [4,29]. In such an approach, each user should trust all other users in the system.…”

Spatial cloaking for anonymous location-based services in mobile peer-to-peer environments

“…This architecture model could pose a scalability issue because it requires all the mobile users to periodically report their exact locations to the location anonymizer. Also, storing the user's exact location at a server could pose a privacy breach, i.e., a single point of attacks [9,10,27]. For the distributed architecture model [9,10], the users maintain a complex data structure to anonymize their location information through fixed communication infrastructure, i.e., base stations.…”

“…For the distributed architecture model [9,10], the users maintain a complex data structure to anonymize their location information through fixed communication infrastructure, i.e., base stations. However, such a complex data structure leads to difficulties to apply this model to highly dynamic location-based mobile applications [27]. For the peer-to-peer model, to our best knowledge, our previous work is the only spatial cloaking algorithm for this architecture model [4].…”

Unchained Cellular Obfuscation Areas for Location Privacy in Continuous Location-Based Service Queries

“…The metadata of the representative are copied to all queries before they are transmitted to the LBS server, thereby satisfying -anonymity and obfuscation requirements. Anonymizers typically create obfuscation areas in grid [7,[10][11][12] or pyramid structure to mask user locations. In [13], a method was proposed to resolve the incompatibility between the original obfuscation area and query criteria by creating an additional obfuscated query area to keep privacy.…”