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Extended Abstract : Cipher Techniques to Protect Anonymized Mobility Traces from Privacy Attacks

We study the problem of privacy protection of openly published mobility traces of people and other real-world entities, beyond standard protection techniques of anonymization and spatial/temporal cloaking. It has been shown that an adversary, armed with side information learned from real-world channels, could use powerful Bayesian inference methods to compromise the standard protection significantly [1]. In this paper, we argue that a major challenge of more effective protection is the need to balance between secrecy for protection and transparency for functional usefulness of the protected traces. We present “classical cipher” techniques applied to the spatial and/or temporal domains to give a useful tradeoff between the two antagonistic requirements. Driven by real-world mobility traces, diverse simulation results illustrate the performance of the proposed location cipher and time-zero cipher. We show that these ciphers can mitigate the privacy problem, and the ciphers work best when combined.