Zeitstempelt

Zeitstempelt is the property of having a time-stamp attached to data, indicating the moment at which the data existed or was created. In digital contexts, a document, file, email, or software artifact can be zeitstempelt to provide a verifiable record of its existence at a specific time, without altering the original content. The term is derived from the German words Zeit (time) and Stempel (stamp).

The typical mechanism involves a trusted third party known as a time-stamp authority (TSA). A hash of the data is created and sent to the TSA, which signs the hash together with the current time to produce a time-stamp token. This token can be stored with the data or separately and can be used later to verify that the data existed in that exact form at the stated time. Because the timestamp is tied to the data’s hash, any modification of the data after stamping would invalidate the token.

Standards and use cases: The Time-Stamp Protocol is defined in RFC 3161 and is widely implemented in digital signature schemes and document management systems. In the European Union, certain time-stamping services can be qualified under eIDAS as trusted time-stamp services, offering higher assurance for legal and regulatory contexts. Common applications include proof of existence for contracts, software releases, academic theses, and financial records, contributing to non-repudiation and audit trails.

Limitations and considerations: The reliability of zeitstempelt data depends on the trustworthiness and security of the TSA and the verification process. A timestamp proves existence at a moment in time but does not necessarily guarantee the accuracy of the clock used by the TSA; ongoing key management and periodic audits are essential to maintain credibility.