ConsentMD: A Single-VM Hyperledger Fabric Consent Architecture for Telemedicine

Abstract Telemedicine systems require reliable audit trails and strict enforcement of patient consent, even when deployed by organizations with limited infrastructure. Permissioned blockchains are often proposed for electronic health record (EHR) and consent management because they bind every action to a cryptographic identity and provide tamper-resistant logs. However, most existing evaluations use multi-node or highly optimized environments, so it remains unclear whether these approaches are practical for small healthcare operators with limited resources. This paper presents ConsentMD, a consent management layer built on Hyperledger Fabric and deliberately evaluated on a single virtual machine (VM) to represent a minimal, resource-constrained deployment. The system comprises a two-organization Fabric network, JavaScript chaincode with fine-grained authorization logic, a Node.js gateway, and a fully automated deployment and benchmarking workflow. Rather than targeting full-scale decentralization, the design focuses on identity-bound consent enforcement and auditable access control within a minimal operational footprint. To separate system capacity from authorization overhead, we introduce an authorized-only benchmarking mode, which excludes access-denied transactions and exposes best-case read and write behavior, alongside an authorization-enabled mode that captures enforcement. Experiments in a controlled four-vCPU envelope representing a low-cost single VM, repeated ten times per configuration, show stable performance. Write throughput increases with the offered rate before plateauing at approximately 46 transactions per second (TPS). An index-backed composite-key consent check enables read throughput above 1,100 TPS with 99th-percentile latency in the tens of milliseconds and no transaction failures. Authorization-enabled reads sustain approximately 930 TPS while rejecting all unauthorized requests. Component-level measurements show that read cost is dominated by the state-database query: indexed lookups complete in about 5 ms, compared with about 23 s without the index. A compromised-gateway test further confirms that the ledger independently blocks unauthorized access. These results indicate that blockchain-based consent management can remain operationally viable at small scale, providing a practical baseline for healthcare operators and a foundation for future multi-node deployments.