Blockchain-Based Decentralised Digital Identity and Public Key Infrastructure Using Hyperledger Fabric: Architecture, Smart Contract Implementation, and Scalability Evaluation for Cross- Organisational Trust Management

Abstract

Public Key Infrastructure (PKI) — the framework of policies, hardware,software, and procedures for creating, managing, distributing, storing, andrevoking digital certificates that bind public keys to verified identities — forms the cryptographic foundation of digital trust in internet communications, from TLS/HTTPS website authentication to document signing, email encryption, and software code signing. Traditional centralised PKI architectures, dependent on trusted Certificate Authority (CA) hierarchies, are vulnerable to CA compromise — as demonstrated by the DigiNotar (2011), Symantec (2017), and DarkMatter incidents — and create scalability bottlenecks at the CA tier that limit throughput under high certificate issuance demand. Blockchain-based decentralised PKI (DPKI) distributes certificate issuance and validation across a permissioned network of nodes, eliminating single-CA dependency, providing an immutable tamper-evident certificate ledger, and enabling cross-organisational identity federation without centralised trust anchors. This paper presents the design, smart contract implementation (Hyperledger Fabric v2.5, Go chaincode), and performance evaluation of a decentralised digital identity and PKI system supporting W3C Decentralised Identifier (DID) v1.0 and Verifiable Credential (VC) standards. The Hyperledger Fabric network was benchmarked against traditional centralised CA and LDAP directory baselines for identity transaction throughput (TPS) at network scales of 1, 2, 4, 8, and 16 endorsing peers. The proposed system achieved 3,240 TPS at 16 peers — linearly scaling with peer count — versus the centralised CAbaseline, which degraded from 8,400 TPS at a single CA server to 4,200 TPSat 16 distributed query nodes due to CA query serialisation bottlenecks. Smart contract execution for certificate issuance averaged 148 ms and forverification 42 ms at 8 peers, meeting the latency requirements of interactive digital identity verification use cases including e-governance, cross-organisational employee verification, and Aadhaar-linked digital credential issuance. KEYWORDS: Blockchain, PKI, Digital identity, Hyperledger Fabric,Decentralised identity, DID, Verifiable credentials, Smart contracts, Digitaltrust, Andhra Pradesh, Certificate authority, Web3