Timestamping is a common technique used to track the date of filing and authenticity of a document, video or image. A clerk stamps your document with the date, time (and sometimes adds a signature) to provide proof that you submitted this document at this time. Stamping prevents anyone, including the owner, from changing the document.
Modern electronic timestamping offers the same assurances with greater security and more convenience:
- A unique digital fingerprint (commonly referred to as hash code or just hash) is calculated from a file. A similar but altered file would result in a different hash and it is virtually impossible for anyone to duplicate hash from the file.
- The computer generates a timestamp, adds it to the file hash, and then generates another unique hash that is derived from both pieces of data.
- The computer then generates an encrypted private key that allows only the key holder to access the recording of the timestamp and file.
- The owner receives the hash and private key (the signed hash) and timestamp information, which when stored with the original document, provides proof that the exact document or image was timestamped. The process is completely confidential because only the derived hash is stored on the computer, not the file. (It is not possible to recreate the file from the hash.)
Most modern timestamping relies on trusted agents for timestamping. These are often government-authorized third-party companies entrusted with running computer systems that process and record timestamps. Some are even qualified by the European Union or governments as meeting the highest security standards.