A collaborative privacy-enhanced alibi phone

This paper presents a collaborative privacy protection approach that not only filters context information and reduces its granularity, but also intelligently replaces the filtered-out context with an artificial context considered appropriate by its user. The benefit of this approach is that individuals accessing the filtered context cannot detect the presence of filtering, namely, filtering becomes imperceptible. This new approach is used as a basis for designing, implementing and evaluating a collaborative privacy-enhanced alibi phone, allowing user to imperceptibly conceal surrounding ambient sound from callers, while leaving callers unaware of this filtering.