Hilbert‐order based spatial cloaking algorithm in road network

Abstract

Location-based services (LBSs) are currently some of the fastest growing information technology industries. User privacy in LBSs has attracted great interest in the research community. However, the proliferation of position identifying devices has become an increasing privacy threat for users in LBSs. It is very difficult to avoid the privacy threat of a user in processing his/her request because the user has to submit his/her exact location with a query to the LBS. To protect privacy in road networks, the existing method employs an X-Star framework to hide the query issuer and provide protection from attack resilience. However, it incurs low anonymization success rate and high computation cost. To solve the problems, we propose a Hilbertorder-based star network expansion cloaking algorithm (H-Star). Our H-Star guarantees k-anonymity under the strict reciprocity condition and increases anonymization success rate by reducing computation overhead. We also propose k-nearest neighbor and range query processing algorithms based on the anonymized region. Through comprehensive experimental analysis, we show the effectiveness of our algorithms in the field of spatial cloaking. different road segments. The cloaker sends cloaked region to the LBS. The LBS retrieves a result set that is guaranteed to contain the query results for any possible user position inside the blur area. When the anonymizer receives a result set, it filters and sends the exact answer to the user. The second group includes techniques without a trusted third party [15-18] called distributed system, where users make a group and select a group head (GH) among them and GH is responsible for handling communication between the users and LBS.However, most existing privacy approaches cannot satisfy users' privacy when they travel in a road network. This is because they consider Euclidean space rather than the road network. Recently,[18][19][20][21] has been proposed to point out this type of problem wherein a cloaking area is created based on road segments rather than a squareshaped cloaking region. Among them, X-Star [14] provides a star-graph-based cloaking model that can protect user's privacy from attack resilience and optimize query processing cost. However, in X-Star, anonymization success rate is very low and computation overhead is quite high. Therefore, in this paper, we propose a Hilbertorderbased star network expansion cloaking algorithm (H-Star), which can protect user's privacy even though adversaries are physically present in a network. The proposed H-Star fulfills reciprocity property, that is, each cloaking region must be shared by at least k users, to preserve user's privacy. It can increase anonymization success rate and decrease computation overhead. To the best of our knowledge, this is the first work that can ensure the above requirements at the same time. We also propose k-nearest neighbor and range query processing algorithms based on the anonymized region. Our contributions can be summarized as follows:We propose a k-anonymitybased clo...

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“…end if 16) end if 17) end for each 18) if (kNum == kNum before ) then 19) if ( , so it continues to call algorithm 2_2. In searching step 1, due to the type of every possible adjacent vertex is intersection, any intersection (e.g., v 2 ) is selected (Figure 2(b) …”

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