Bob-Tree: An Efficient B + -Tree Based Index Structure for Geographic-Aware Obfuscation

The privacy protection of personal location information increasingly gains special attention in the field of location-based services, and obfuscation is the most popular technique aiming at protecting this sensitive information. However, all of the conventional obfuscation techniques are geometry-based and separated from the database level. Thus, the query processing has two timeconsuming phases due to the number of disk accesses required to retrieve the user’s exact location, and the location obfuscation. Also, since these techniques are geometry-based, they cannot assure location privacy when the adversary has knowledge about the geography of the obfuscated region. We address these problems by proposing B-tree, an index structure that is based on B-tree and contains geographic-aware information on its nodes. Experiments show that B-tree provides a significant improvement over the algorithm separated from the database level for query processing time and location privacy protection.