Tidsstemples

Tidsstemples, or time-stamps, are records that establish that a piece of data existed at a specific moment. In digital contexts, a tidsstempel provides evidence of the date and time at which a document, file, or message was created, modified, or received, without necessarily revealing the data itself. They are commonly used to support claims of authorship, ownership, or compliance in legal, financial, and archival settings.

In practice, a tidsstempel is generated by a trusted timestamping authority (TSA). The process typically involves computing a cryptographic hash of the data, sending the hash to the TSA, and receiving a signed timestamp token that includes the hash, the exact time, and the TSA’s digital signature. The original data can remain unaltered; to verify, you recompute the hash and validate the signature against the TSA’s certificate. Timestamps can be attached to the data itself or stored separately as verifiable tokens.

Applications include digital signatures and contracts, software release management, long-term digital archival, forensic investigations, and regulatory compliance. They are also used to anchor events in distributed systems to provide external and independent time references.

There are different forms of tidsstemples: remote trusted timestamping via a TSA, local or self-timestamping which may carry weaker assurances, and embedded timestamps within metadata. Standards such as RFC 3161 define the Time Stamp Protocol and related mechanisms for issuing and validating timestamps. Limitations include reliance on the TSA’s clock accuracy, privacy considerations from revealing timing information, and the need for periodic re-timestamping to maintain long-term validity as cryptographic standards evolve. Related topics include the Time Stamp Protocol, trusted timestamping services, and long-term validation.