Privacy Preference Signals: Past, Present and Future

Abstract Privacy preference signals are digital representations of how users want their personal data to be processed. Such must adopted by both the sender (users) and intended recipients (data processors). Adoption represents a coordination problem that remains unsolved despite efforts dating back 1990s. Browsers implemented standards like Platform for Preferences (P3P) Do Not Track (DNT), but vendors profiting from faced few incentives receive respect expressed wishes subjects. In wake recent privacy laws, coalition AdTech firms published Transparency Consent Framework (TCF), which defines an optin consent signal. This paper integrates post-GDPR developments into wider history signals. Our main contribution is high-frequency longitudinal study describing TCF signal gained dominance as February 2021. We explore factors correlate with adoption at website level. Both number third parties on presence Google Ads associated higher TCF. Further, we show acted early adopters 2.0 provide two case-studies Management Providers shifted existing customers 2.0. sketch ways forward pro-privacy