A Users Collaborative Scheme for Location and Query Privacy

In location based services (LBSs) of snapshot query, both of query and location privacy should be preserved. Most preceding schemes usually employed a trusted third party (TTP) to achieve k-anonymity, and perturb the real query and location with other k-1 users, but this scheme may be influenced by the single point failure and performance bottleneck. In order to solve this problem, another scheme to achieve k-anonymity with collaborative users through short-range communication was proposed. After deeply analyzing the inherent drawbacks of existing schemes of this type, we have found that most of them mainly focus the location privacy and usually neglect the correlation between query and location. In order to preserve the query privacy, based on the user collaborative scheme, we propose a scheme with query information divide and exchange with random users (short for QDER). This scheme can provide preserving service for both query and location privacy simultaneously. Then we analyze the attack from passive and active adversaries and use entropy to measure the privacy level. Finally, security analysis and experimental evaluations further verify the effectiveness and efficiency.