A Policy-Based Conjunctive Scheme for Digital Forgetting of Co-Owned Data

In today’s digital landscape, our interactions, from professional collaborations to personal data sharing involving photos, movies, and documents, have largely moved online. While transitioning these activities to digital platforms provides considerable convenience, it poses significant challenges in efficiently managing and securely erasing shared data in compliance with privacy regulations. Digital forgetting, particularly in co-owned data, transcends being merely desirable and becomes a mandate. Conventional data management paradigms, including cryptographic erasure techniques, typically apply uniform deletion across all stakeholders, neglecting audience-specific expiration and co-owner participation in deletion, which limits their applicability in contemporary cloud storage ecosystems. This paper introduces a Policy-Based Conjunctive Scheme (PBCS) that enables conjunctive decision-making for data access and collaborative data forgetting, aligning with the General Data Protection Regulation (GDPR)’s Right to be Forgotten (RTBF). PBCS allows owners to upload their data to the cloud securely and offers policy-based access control to co-owners, granting them the ability to influence decisions about data deletion via democratic voting mechanisms significantly. The scheme leverages conjunctive access thresholds and mechanisms that gradually make data irretrievable. By integrating cryptographic primitives and Lagrange interpolation-based decay, PBCS supports a flexible, conjunctive governance model that upholds privacy and enhances the data lifecycle. We provide a formal analysis and an experimental evaluation of our scheme.