A Decentralised Public Key Infrastructure for X-Road

X-Road is an open-source solution that acts as a data exchange layer and enables secure data exchange between organisations. X-Road serves as the backbone of digital infrastructure in the public sector (e.g., enabling Estonia's digital public services) and private sector (e.g., enabling clients' data exchange in the Japanese energy sector). An approach and architecture were recently proposed for the X-Road data exchange systems to move from public key infrastructure (PKI) with centralised certification authorities to de-centralised PKI (DPKI). In this paper, we develop a proof of concept for the designed DPKI-based architecture that leverages distributed ledger-based identifiers and verifiable credentials to establish trust between information systems using Hyperledger Indy and Hyper-ledger Aries. We evaluate the proof of concept implementation against the design and functional requirements. The results show that the proposed system architecture is technically feasible and satisfies the identified design goals and functional requirements. To the best of our knowledge, this paper presents the first open-access system prototype for an organisation's identity management following self-sovereign identity principles. The presented proof of concept proves that DPKI helps to address some of the scalability issues of PKI, improve control over identity and mitigate replay attacks and a single point of failure in the X-Road system.