Proof of retention secures auditable data sharing across organizations
Proof-of-Retention: A Framework for Auditable Cross-Organization Data Sharing
Databases
Summary
Sharing data between companies is important but raises privacy and legal concerns. The authors propose Proof-of-Retention, a system that lets organizations prove they still keep part of the shared data without revealing everything. This helps auditors verify compliance with data-sharing rules while protecting privacy. The system combines database methods with cryptographic tools and works efficiently without copying all data.
What this means in practice
- •For enterprise data teams: Verify that partners comply with data retention policies without full data transfer or invasive monitoring.
- •For cloud service providers: Offer secure auditing services that help customers prove data sharing compliance using proof-of-retention protocols.$Commercial implications: Enables cloud providers to sell compliance verification tools to organizations handling sensitive shared data.
Authors
Kyle MacMillan, Sanjay Krishnan
Abstract
The rapid adoption of AI across industries for (e.g.) fine-tuning and analytics has accelerated the need for high-quality data. To satisfy this demand, public and private entities will buy and sell data with other organizations. But such data sharing can and does violate privacy norms and laws. EU and American lawmakers have endeavored to control data sharing, restricting what data may be shared with whom, and under what circumstances. Unfortunately, accurately assessing compliance with new regulatory regimes remains a challenge, as data provenance, that is, metadata about data sharing, is rarely preserved. And even when provenance information is retained, unilateral changes to one party's database can render the provenance stale. To fill this gap, we present Proof-of-Retention a novel framework and interactive protocol that enforces auditable data sharing. Our framework requires each party involved in data sharing to retain a subset of information associated with each data exchange, and provides a mechanism for auditors to verify that the parties have indeed retained that information. Our approach combines techniques from database systems, including query witness generation, with cryptographic proof-of-possession protocols to provide retention guarantees. The framework enables efficient auditing that does not require full data replication or intrusive monitoring, thereby preserving privacy and remaining practical. We formalize the protocol, analyze its security and performance properties, and provide a reference implementation built on AWS infrastructure.