SpexPay: A Privacy-Preserving Pay-As-You-Go System for Dynamic Spectrum Sharing

2026-07-19

AI Summary

This work addresses the privacy and auditability limitations of existing centralized dynamic spectrum sharing systems, which often leak sensitive metadata and lack secure transaction mechanisms. We propose SpexPay, a privacy-preserving, auditable pay-per-use spectrum access framework that uniquely integrates BBS+ verifiable credentials, unlinkable session pseudonyms, and selectively disclosed zero-knowledge proofs to enable anonymous yet usage-bound authorization and payment. The system stores only pseudonymous usage evidence and hash-chain-based metering data on-chain, achieving strong privacy without compromising auditability. Prototype evaluation demonstrates an end-to-end latency of approximately 150 ms, on-chain costs of about 603K gas (≈USD 0.9), and feasibility for edge deployment, as validated on a Raspberry Pi 5.

Abstract

Dynamic Spectrum Sharing (DSS) is a cornerstone of next-generation wireless systems, yet existing solutions such as Spectrum Access Systems (SAS) rely on centralized administrators that expose sensitive operational metadata and lack cryptographic transaction accountability. Though SAS administrators, such as Google, have introduced pay-as-you-go pricing models, these approaches still face significant privacy and accountability challenges as DSS evolves toward a more open and large-scale spectrum marketplace. We present SpexPay, a privacy-preserving and auditable pay-as-you-go spectrum usage framework that enforces fine-grained, usage-linked payments without revealing user identities. Spexpay integrates BBS+ verifiable credentials, unlinkable session pseudonyms, and selective-disclosure proofs to enforce privacy-preserving access authorization, while leveraging Solidity-based smart contracts to realize automated and non-repudiable escrow settlement. By recording only pseudonymous usage evidence and hash-chained metering data on-chain, the system achieves strong unlinkability while preserving verifiable accountability and auditability. A full prototype demonstrates low end-to-end latency ($\approx$150 ms) and modest on-chain cost ($\approx$603K gas or $\approx$\$0.9), showing that SpexPay is practical for real-world DSS deployments. We also evaluated the user-side cryptographic operations on a Raspberry Pi 5 to assess scalability and suitability for edge-class hardware. Our code and artifacts are publicly available at https://github.com/iambarat/SpexPay.

Problem

• Dynamic Spectrum Sharing
• Privacy
• Accountability
• Pay-As-You-Go
• Spectrum Access Systems

Innovation

• privacy-preserving
• verifiable credentials
• smart contracts
• dynamic spectrum sharing
• unlinkability