What is trusted timestamping and how does it work?
Trusted timestamping is the process of securely recording the creation or modification time of a document so that neither the owner nor anyone else can alter it after the fact. A user sends a cryptographic hash of their document to a Time Stamping Authority, which appends a time value, signs the combined hash with its private key, and returns the signed token. Verification is done by recomputing the hash and comparing it against the TSA's signed record.
Who first discussed trusted digital timestamping in published literature?
Stuart Haber and W. Scott Stornetta were the first to discuss trusted digital timestamping in the published literature.
What standards govern trusted timestamping?
The RFC 3161 standard defines the core trusted timestamp framework, including the role of the Time Stamping Authority. The ANSI ASC X9.95 Standard builds on RFC 3161 by adding data-level security requirements tied to a reliable time source, and has been applied to financial transactions, regulatory compliance, and legal evidence.
How did Robert Hooke use an early form of timestamping in 1660?
In 1660, Robert Hooke concealed his discovery of the law of elasticity inside the anagram ceiiinosssttuv rather than publishing it immediately. He later revealed the translation ut tensio sic vis, proving he had made the discovery before anyone else while protecting the details in the meantime.
What are the different types of trusted timestamping schemes?
The main schemes are PKI-based, linking-based, distributed, transient key, MAC, database, and hybrid. The linked-and-signed hybrid is the most widely used in practice. Masashi Une's published work provides a systematic classification and evaluation of these approaches.
Can blockchain be used for trusted timestamping and what are its limitations?
Blockchain can be used for timestamping by embedding a document hash into a transaction, with security derived from the computational effort accumulated after the hash is recorded. Bitcoin in particular allows timestamps up to two hours in the future and accepts blocks with timestamps earlier than the preceding block, which limits the precision of Bitcoin-anchored timestamps.