Overview
ISO/IEC 18014-3:2009 specifies mechanisms for time-stamping services producing linked tokens. It defines a general model, core components, data structures and message formats, and a protocol to extend linked time-stamp tokens to values published by a Time-Stamping Authority (TSA). The standard describes how TSAs can cryptographically link time-stamp tokens together to provide verifiable evidence that data existed at particular points in time while strengthening token security without depending solely on PKI trust.
Key Topics and Requirements
- Linked token model: Defines how time-stamp tokens (TSTs) can be related to earlier tokens using cryptographic links.
- Linking operations: Three supported linking methods are specified: linear chain linking, anti-monotone binary linking, and threaded tree linking.
- Core operations: Includes linking, aggregation, publishing, extend, verify, and renew processes for token lifecycle management.
- Message formats: Standard request/response structures for Time-stamp Request/Response, Verify Request/Response, and Extend Request/Response.
- Data types and structures: Defines objects such as TSTInfo, TimeStampToken, BindingInfo, Chain, Link, Node, and PublicationInfo; ASN.1 module provided in Annex A for interoperable encoding.
- Hash-function requirements: Recommends use of collision-resistant hash-functions in line with ISO/IEC 10118 to ensure pre-image and collision resistance when forming links.
- Extend protocol: Defines how tokens can be extended with references to published values, enabling long-term verifiability and public auditability.
- Security considerations: Emphasizes repository integrity, cryptographic verification of linking operations, and minimizing assumptions about key compromise or PKI trust.
Applications and Who Uses It
- Time-Stamping Authorities (TSAs) implementing robust, provable time-stamping services.
- Software vendors and system architects building secure audit logs, digital evidence systems, blockchain or archive services requiring verifiable temporal bindings.
- PKI engineers and security architects who integrate time-stamping with signature systems or long-term validation services.
- Legal, forensic and compliance teams relying on auditable timestamps for electronic records, contracts, or regulatory evidence.
- Researchers and implementers needing standard data structures (ASN.1) and interoperable protocols for linked token services.
Practical uses include tamper-evident event logging, long-term archival timestamping, and multi-step timestamp chains that provide public proofs of existence without exposing original data.
Related Standards
Keywords: ISO/IEC 18014-3, time-stamping services, linked tokens, time-stamp token, TSA, collision-resistant hash, ASN.1, extend protocol, cryptographic linking.