GAMP 5 - Good Automated Manufacturing Practice D10: Appendix D10 Distributed Ledger Systems

Distributed ledger networks that record data from several participants using cryptography, consensus, smart contracts and replication may support GxP processes such as supply chain track and trace, and the guide gives the GxP practitioner considerations for relying on them once a use case and protocol have been chosen, focusing on large-scale public networks. The network layer with its database and operating functions is treated as infrastructure, smart contracts as custom or configured software depending on origin, the data and transaction logs under records and data integrity principles, and permissioned second-layer networks as shared computing environments; governance rests with independent node operators, business partners are known by the addresses they control, and GxP considerations apply to the ancillary systems and interfaces that push and pull information as much as to the network. In the concept phase business process mapping documents intended use, ancillary systems, high-level risks, smart contract logic, the network's role, on-chain and off-chain data and the protocol, with data flow and swim-lane diagrams and a systems-engineering view of interactions, and smart contracts are reviewed through standard code review. In the project phase a governance structure is established early, ledger-as-a-service providers are assessed per supplier assessment with added questions on node management, off-chain storage and key custody; data is understood in terms of where it originates, which copy is authoritative and who owns it with data quality controls keeping the ledger in sync and hash verification of referenced metadata; controls are defined for inputs, outputs, processing and access, covering event identification, data quality, correction of off-chain data, interface transformation, hash matching, visualization accuracy, reliance on specific elements, omitted transactions, interface monitoring, reconciliation, protocol change control, failed transactions, transaction costs, network stability, address authority and attribution, authentication, private key custody, off-chain database security, privacy mechanisms, allow and deny lists and interface security; change management covers the whole use case with protocol governance treated like open-source software and forks considered; composable and upgradable smart contracts and external data feeds need change control with standard and custom contracts distinguished. Retirement or migration plans for retaining data if the network is abandoned, cryptographic agility, and the limits of migration where history, addresses and continuous security cannot be recreated. Other considerations are the maturity, vendor support and pace of change of the technology, interoperability and security standards with hardened standard contracts, third-party review and test networks, reliance on accepted cryptographic algorithms, the risks and accounting implications of transaction fees and value held in addresses, and privacy through avoiding sensitive on-chain data, encryption, key management and anonymization.