A Rootchain-Centric Hierarchical Multichain Architecture for National Blockchain Infrastructures: Design Rationale and Empirical Evaluation for Mid-Sized Nations With Consolidated Digital Governance

Abstract

National-scale blockchain infrastructure must simultaneously deliver data residency, auditable governance, and sector-scale performance. Existing large-economy permissioned blockchain designs for national infrastructure, including China’s Blockchain-based Service Network (BSN) and the European Blockchain Services Infrastructure (EBSI), adopt federated or peer-to-peer topologies that suit cross-jurisdictional politics but impose coordination overhead on nations governed under a single administrative domain. This paper proposes, formalizes, and deploys a rootchain-centric hierarchical multichain architecture that powers Vietnam’s national blockchain infrastructure. We build a permissioned Rootchain on Hyperledger Besu with QBFT consensus and operate it as a unified trust anchor and control plane for extensible sector-specific Domain Chains. The Rootchain manages admission, permission registries, audit trails, cross-chain traceability, and verifiable proof-of-control. At its technical core, we introduce a dual-gate authorization algorithm that couples W3C Decentralized Identifiers (DID) and Verifiable Credentials (VC) with on-chain state-proof verification, enabling direct Domain-Chain-to-Domain-Chain interaction without continuous Rootchain round-trips. We further design a Threshold Governance Key (TGK) scheme based on m-of-n multi-signature and hardware security modules that supports emergency actions with on-chain auditability. We implement the architecture and deploy with a geographically distributed testnet of 5, 7, 10, and 14 validators. Our evaluation shows that the Rootchain achieves about 800 write transactions per second with the finality under 3 seconds at the 99th percentile. The testbed shows that the aggregate ecosystem throughput scales proportionally with the number of parallel domain chains, showing the projection of a highly scalable system. Comparative analysis confirms lower governance complexity, faster chain onboarding, and real-time credential revocation versus state-of-the-art national designs, making the architecture suitable for mid-sized nations with consolidated digital governance.