Anonymous provision of privacy-sensitive services using blockchain and decentralised storage

Abstract Lawyers, laboratories, auditors, and banks often need access to sensitive personal data to provide services such as genetic testing, paternity testing, STD testing, credit scoring, or legal advice. Processing such data exposes both service providers (SPs) and users to privacy risks: SPs risk violating laws like the General Data Protection Regulation (GDPR) and the Consumer Protection Act (CPA), while users risk losing their privacy. We observe that personal data is often only needed for logistical purposes like payment or communication and could be provided anonymously if suitable methods existed. To address this, we present a solution that enables services to be delivered without collecting personal data. Our protocol combines anonymous payment methods (e.g., cash, privacy-preserving cryptocurrencies), blockchain for fairness, and distributed content-addressable storage networks to deliver results. Compared to existing approaches, our protocol achieves anonymity under weaker assumptions, supports the transfer of physical materials and conflict resolution, and eliminates the need for customer interaction with a trusted arbiter in conflict-free cases-making it more practical. We analyze the protocol’s fairness and implement a prototype using Ethereum as a message board, Monero for anonymous payments, and Powergate (IPFS/Filecoin) as a decentralized storage solution.