Aikaleiman

Aikaleima, commonly translated as a timestamp, is a record of a specific date and time attached to a data item to indicate when the item existed or was created. In Finnish, aikaleiman is the genitive form of aikaleima.

In digital contexts, a digital aikaleima provides evidence of when a file, message, or signature existed in a given state. The typical process involves a user submitting a cryptographic hash of the data to a timestamping service. The service applies its trusted time, signs the hash with its private key, and returns a time-stamped token. Later, the data and the token can be verified by checking the service’s public key and ensuring the hash matches the data at the stated time.

Standards for digital timestamping include RFC 3161, which defines a Time-Stamp Protocol, and ISO/IEC 18014, which specifies time-stamping mechanisms and verification procedures. Verification generally ensures the token has a valid signature from a trusted timestamp authority and that the included time is credible and within acceptable bounds.

Applications of aikaleima span legal and archival domains, software provenance, and data integrity for long-term preservation. They help establish non-repudiation and reduce the risk of later modification going undetected. Limitations include the reliance on trusted time sources and authorities, potential privacy considerations when timestamps reveal sensitive timing information, and the need for ongoing security of the timestamping infrastructure. Overall, aikaleimat are a key tool for proving the temporal existence and integrity of digital evidence and records.