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Time stamp is a tool that provides a reliable way to attach a trusted time information to the existing data, information, files or events, based on trusted time source derived from UTC time.

Archival electronic time stamps have the same attributes as the standard electronic time stamps, ie:

  • The time stamp is a data message, which proves the existence of a document at a certain time.
  • Serves as a proof that the data object to which it relates existed immediately before the time stamp stated in the time stamp.
  • Attaches the current time to existing data, information, files or events.
  • Connection of the time with a specific data is particularly necessary for the purposes of their re-verification.
  • The time stamp contains the date and time of its issuance, the unique number of a time stamp, identification of a third party that issued the timestamp (certification services provider), fingerprint (hash) of the data for which the time stamp was issued and an electronic sign of the electronic certification service provider who issued the stamp.

The time during which the relying party can verify the standard time stamp is limited by a validity of the certificate on which the electronic sign of a certification authority used to sign a time stamp is based. A validity of this certificate is usually 3 years.

Therefore I.CA offers archival time stamps service, which is based on the technology of time stamps, their chaining and storing. The principle of the service is based on RFC 4998 Evidence Record Syntax. The first time stamp is time stamps the original document, the second stamp in a row time stamps the first time stamp, etc. I.CA doesn’t work with the original document. This service is offered as fully operated in I.CA environment.


The client receives standard time stamps, the internal application of I.CA pays attention on the validity of the certificate on which the time stamp is based (a certificate of the time stamp authority). Before its expiration, but not sooner than before issuing new time stamp authority certificate, the application time stamps the previous time stamp and stores it in the internal I.CA‘s systems. Upon the client’s request I.CA provides to the client:

  • a service for searching a particular time stamp
  • a time stamped time stamp
  • the protocol on the time stamp chain signed by I. CA
  • a complete structure for the needs of an independent expert

Archival electronic time stamps are used to save documents or data for a longer period of time (about 10 or more years) in a way that allows to prove an existence of the particular document in a particular time.

Using the ATSA service in an environment of I.CA. can save considerable amounts of money needed to build a trusted repository. All responsibility for proving the validity of all chained time stamps (and therefore the validity of the original document) are guaranteed by I.CA.

Registration authorities



8/28/2019 Swedish partnership
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7/16/2019 I.CA starts issuing certificates using elliptic curve cryptography (ECC)
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3/27/2019 I.CA became a member of the OBE QTSP Working Group
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