Privacy Preservation in the Publication of Trajectories

The authors study the problem of protecting privacy in the publication of location sequences. Consider a database of trajectories, corresponding to movements of people, captured by their transactions when they use credit or RFID debit cards. They show that, if such trajectories are published exactly (by only hiding the identities of persons that followed them), there is a high risk of privacy breach by adversaries who hold partial information about them (e.g., shop owners). In particular, they show that one can use partial trajectory knowledge as a quasi-identifier for the remaining locations in the sequence. They device a data suppression technique, which prevents this type of breach, while keeping the posted data as accurate as possible.