A Hybrid Blockchain-PKI Architecture for Interbank Guarantee Systems

Abstract

Bank guarantees remain vulnerable to fraud, including document forgery and unauthorized issuance. This study develops a novel hybrid interbank guarantee platform integrating Public Key Infrastructure (PKI)-based digital signatures with a public blockchain to enhance authenticity, integrity, and traceability. A prototype was designed and evaluated based on requirements identified through consultations with twenty practitioners. The proposed architecture demonstrates the potential of combining PKI and blockchain to improve the security and trustworthiness of digital bank guarantee systems. Under load testing with 100 concurrent virtual users, the prototype maintained an average backend response time of around 70 ms at peak load, with tail latency below 3.6s and an indicative on-chain cost of approximately USD 0.001 per transaction. The findings demonstrate the feasibility of integrating PKI and blockchain for interbank guarantees, while providing a replicable framework for guarantee digitalization and practical guidance for financial institutions, technology providers, and policymakers