Abstract: With the development of social network applications,and to meet the demand of mobile system designing and scientific research,plenty of location trace information has been collected and published．Most public traces utilize the anonymous ID and adding noise to protect the privacy of users．However,these processes are vulnerable when facing asynchronous attack．Even if partial information was exposed to adversary and the collections of side information and public trace set are not in the same duration,the adversary can also identify user’s ID with high accuracy．Our experiment shows that the existing method is not applicable when facing asynchronous side information．A novel method applicable in asynchronous condition was proposed which is called hot-matrix method．To verify this method,we employed experiments in three different mobility trace sets,whose subject is taxi,bus and human beings respectively．Experiments show that hot-matrix method performs much better than existing approach．

Key words: Anonymilization,Mobility trace,Identification,Geographical hot spots