Cloaking sensitive patterns Td preserve location privacy for LBS applications

To protect privacy while using LBS, we propose a pattern-based cloaking system that incorporate a trusted privacy preserving server to compute the cloak region for each sensitive patterns. To prevent adversaries culling out some patterns with some simple clues, we define a pattern-safe-cloak (PSC) region as a rectangle area that contains at least other l-1 reasonable and dissimilar patterns. To facilitate the search of a minimal PSC region for sensitive patterns, we use an R-tree to store the spatially distributed insensitive patterns. Our initial study results show that although the average area of the optimal PSC regions discovered is smaller than that of the first discovered PSC regions, the cost of finding optimal PSC region is much higher.