Decentralized system enforces data access policies with majority approval
Beyond Centralized Policy Decision Points: Decentralized Sticky Policy Authorization through Evidence Quorums
Cryptography and Security
Summary
Data often comes with rules attached that tell who can see it and how it can be used. Usually, a central authority checks these rules whenever someone tries to access the data. The authors created SPEAR-Q, a system that spreads out this check across many independent nodes. These nodes each decide if access is allowed, and a majority must agree before access is granted. This setup helps keep data rules intact without relying on a single authority and was tested using simulations and healthcare data.
What this means in practice
- •For healthcare data teams: Maintain consistent patient data access rules across multiple healthcare systems without relying on a central authority.
- •For cloud security administrators: Deploy distributed authorization checks to ensure access policies remain enforced even if some nodes are compromised or offline.
Authors
Aleena Nazir, Mubashir Husain Rehmani, Bernard Butler, Donna O'Shea
Abstract
Sticky policies remain attached to protected data so that access restrictions can persist across systems, yet request-time authorization often still depends on a centralized Trusted Authority or Policy Decision Point (PDP). This paper presents SPEAR-Q, a decentralized framework in which independent Policy Authority Nodes (PANs) evaluate the active sticky policy using local context, consent, and risk information and generate signed authorization evidence. A strict-majority Evidence quorum determines the global Permit or Deny decision, while a committed policy becomes active only after the required PAN majority applies it. SPEAR-Q was deployed across physically separated hosts in the Airbus Cyber Security Simulation Platform and evaluated using a healthcare workload derived from MIMIC-IV. Across 9,000 performance requests, all requests completed without execution failure or timeout. Latency increased and throughput saturated as cluster size and concurrency grew, with PAN evidence waiting and PAN-local processing dominating under load and credential validation forming the main PAN-side cost. Policy-activation experiments confirmed majority-based activation. Quorum experiments showed that correctly signed false-Permit evidence from fewer compromised PANs than the required quorum could not produce a global Permit or resource release, while authorization remained fail-closed when reachable PANs fell below the required quorum. Compared with prior approaches that decentralize policy management, credential authority, or threshold-based release separately, SPEAR-Q integrates persistent sticky policy enforcement, independent request-time evidence, majority-based policy activation, and explicit quorum-bounded authorization within one decentralized framework. Under the evaluated conditions, SPEAR-Q supports decentralized sticky-policy authorization without relying on a centralized decision authority.