Overview

This Wikipedia article defines linked timestamping, a form of trusted timestamping in which each issued time-stamp cryptographically references earlier ones so the entire history forms a tamper-evident, ordered chain. It relies on authenticated data structures (linear hash chains, Merkle binary hash trees, skip lists) rather than on long-term signing keys, so its security rests on the collision and preimage resistance of the hash function instead of on a private key or a single trusted server. The article covers the core operations, the security rationale, the historical development from early 1990s research, and the relevant standards.

Key points

• Three-phase pipeline: aggregation groups requests arriving in a short interval, linking binds the current token to prior tokens, and publishing periodically posts links to hard-to-modify, widely witnessed media such as a printed newspaper or a public blockchain.
• No long-term private keys are used, avoiding PKI and key-compromise risk; forging or reordering a token becomes nearly as hard as finding a hash preimage, and no server, including the issuer, can silently backdate entries.
• Time-stamps are relatively comparable by design, so tampering with absolute time is detectable through the ordering enforced by the chain.
• Pioneered by Stuart Haber and W. Scott Stornetta (hash-chain linking, 1990), with tree-based schemes from Benaloh and de Mare (1991); Surety launched the first commercial service in January 1995, and later work by Buldas, Saarepera, Laur, and others added security proofs and tree optimizations.
• Standardized in ISO 18014 part 3, ANSI ASC X9.95 (2005), and referenced by RFC 4998 (Evidence Record Syntax) for long-term archival integrity.

Relevance to Truestamp

Linked timestamping is the conceptual foundation of Truestamp: items are aggregated into RFC 6962 Merkle trees, each block links prior state, and block roots are periodically recorded on public blockchains, giving a submission window and block commitment without depending on a single signing key. The article’s emphasis on publishing to widely witnessed media parallels Truestamp’s use of public randomness and public-blockchain commitment as independent witnesses.

Citations

1. Linked Timestamping (Wikipedia). Wikipedia, community-maintained; summarizes research from Haber, Stornetta, Buldas, and others.