Overview
ISO/TR 23455:2019 provides a technical overview of smart contracts in blockchain and distributed ledger technology (BC/DLT) systems. It explains what smart contracts are, how they operate within DLT platforms, and how multiple smart contracts interact. The report focuses on technical aspects (architecture, execution, lifecycle and interoperability); legal enforceability is only briefly discussed. This Technical Report was prepared by ISO/TC 307 and is intended as guidance rather than a prescriptive standard.
Key technical topics and considerations
- Definitions and history: clear working definitions of smart contracts, ledger, token, transaction, on‑chain vs off‑chain, and DLT oracles; background from Szabo to modern BC/DLT implementations.
- Operation of smart contracts: the concept of a smart contract as a computer program stored on a distributed ledger and how execution outcomes are recorded.
- On‑chain vs off‑chain: deployment and execution differences, trade‑offs for determinism, performance and trust.
- Access to real‑world information (DLT oracles): patterns for bringing external data on‑chain, event delivery, and transferring control between smart contracts and external processes.
- Life cycle management: creation, operation, modification, termination, migration, update and rollback mechanisms supported by ledgers.
- Security: technical security considerations specific to smart contract code, execution environments and ledger interactions.
- Inter‑contract interaction and interoperability: methods for interaction between multiple smart contracts, cross‑chain and sidechain transaction implementations, and importance of semantics, syntax, inputs and language choices for interoperability.
- Informative annexes: examples of implementations, domain‑specific languages (DSLs), and a catalogue of applications and use cases.
Practical applications and who uses this report
ISO/TR 23455:2019 is useful for:
- Blockchain developers and architects designing smart contract systems and integration patterns.
- Platform vendors and system integrators evaluating on‑chain/off‑chain trade‑offs, oracles and cross‑chain strategies.
- Solution designers in finance, supply chain, identity and IoT seeking technical guidance on lifecycle, security and interoperability of smart contracts.
- Standards bodies, regulators and technical managers who need a neutral, technical reference on smart contract mechanics (not legal advice).
Related standards and references
- Prepared by ISO/TC 307 (Blockchain and distributed ledger technologies).
- Cross‑references within the report include other ISO/IEC and ISO technical reports cited for terminology and related concepts (examples in the text include ISO/IEC 14776‑323:2017 and ISO/TS 19299:2015).
ISO/TR 23455:2019 is a technical reference to help practitioners understand smart contract mechanisms, security considerations, and interoperability challenges in modern BC/DLT systems.