Geohash coding location privacy protection scheme based on entropy weight TOPSIS

The traditional k-anonymity technique does not consider comprehensive factors when choosing anonymous locations, resulting in a high risk of privacy leakage in the final generated anonymous set. In order to construct a secure anonymous set, this paper proposed a Geohash coding location privacy protection scheme based on entropy weight TOPSIS (GLPPS-EWT). First, in order to reduce unnecessary time consumption caused by repeated encoding of historical locations, locations are cached into prefix tree based on Geohash codes. Second, considering attackers may have background knowledge so that locations initially filtered according to historical query probability and semantic distance. Finally, considering the semantic diversity, semantic sensitivity and anonymous area of anonymous set, the entropy weight method is used to determine the index weight and make multi-attribute decision on the candidate set. The optimal anonymous location is selected to construct secure anonymous set. The experimental results show that GLPPS-EWT has good performance and high privacy.