| In recent years, the rapid development of mobile Internet, has been throughout all areas of our lives. In mobile Internet applications, location-based services (LBS Location based service) occupies a large proportion, it makes people’s work and life more convenient. LBS service provider need the user’s location information to provide services, In the process of providing services, if a malicious attacker by attacking or eavesdropping, access to the mobile user’s location information, or LBS service providers to abuse the location information of mobile user, will seriously threaten the position of the mobile user privacy, which bring great safety hidden trouble. Therefore with the widely application of the LBS service, LBS location privacy protection more and more important, has become a research focus in the current.LBS location privacy protection schemes have three main types, and they are protection scheme based on trusted center, protection scheme based on P2P multi-user collaboration and no letter collaboration center and users of client server model. These schemes are mainly based on K-anonymous, encryption, false position technology and so on. Among them, the location privacy protection scheme based on anonymous center server introduces trusted third party, but trusted third party is easy to become the performance bottleneck and a center of attack. Aiming at this problem, there are two kinds of schemes, respectively is the location of the multi-user collaborative privacy protection scheme and location privacy protection scheme based on client server. However, these two schemes still exist defects such as collaborative users don’t credible, mobile terminal load too much defects, therefore, they need further research and improvement.This paper mainly studied the multi-user collaboration scheme based on P2P mode and location privacy protection scheme based on client server. Research results are as follows:1. I proposed a location privacy protection scheme in P2P model based on a multi-user collaboration with random expanded circle and inquiries transformation. Introducing the factor of the user’s movement speed when building an anonymous collection made the scheme more realistic applied. In addition, introducing a limit parameter which is maximum set radius RR made up the vulnerability of high-density. At query time, the collection members all used the random round center to replace their true positions, so the problem that the collaboration with users can’t be trusted was solved. Besides, using the method of inquiry transformation improved the accuracy of the query service.2. I proposed a new improved location privacy protection scheme based on PIR. The scheme had the following advantages. At first, a grid index was constructed in the mobile terminal to meet the user’s individual privacy needs.Then I introduced caching mechanism in the service side to improve the efficiency of query.At last, I applied homomorphic encryption technology in the mobile and server-side to protect the grid index information, thus ensuring the privacy of the mobile user’s location.3. I made theoretical analysis and simulation for two schemes proposed in this paper. The results showed that, compared with the existing schemes, the two schemes were proposed in this paper can improve the accuracy of query results, and can resist attacks of anonymously district center, continuous query attacks, masquerading user attack and high-density attacks and so on. In addition, the query efficiency in the service side of the second scheme was also improved, and the second scheme can also resist the background knowledge of geographic information attacks. |
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