ANF AC´s Public Key Infrastructure (PKI)


The Time Stamping Authority (TSA) is a certification service provider that provides certainty about the pre-existence of electronic data at a specific time, and certifies this data has not been altered in a specific time frame.

ANF AC, as the Timestamping Authority (TSA), issues Digital Time Stamps. This service has been designed following international recommendations and standards:

  • IETF RFC 3161 Time-Stamp protocol (TSP).
  • IETF RFC 3628 Policy Requirements for Time-Stamping Authorities (TSAs).
  • IETF RFC 1305 Network Time Protocol (NTP v3).
  • ETSI TS 102 023 Electronic Signatures and Infrastructures (ESI); Policy requirements for time-stamping authorities.
  • ETSI TS 101 861 TSA time-stamping protocol.

For the creation and signature of the issued stamps, ANF AC has an international infrastructure of servers (UE and Latam), which function as Time Stamp Units (TSU). Each unit uses a qualified electronic certificate that allows identification.

The Time Stamping Service is an online service with high availability and exclusive access for users with an electronic certificate in force issued by ANF AC. In electronic signatures, prior to the issuance of TimeStamp, online Certificate Status Protocol (OCSP) consultation is carried out to determine the validity status of the electronic certificate used. ANF AC validates the electronic signature generated by the signer, stamping day and time in coordinated universal time (UTC), signing and granting an exclusive transaction number, as accreditation of the activity performed. TimeStamp is an essential element that allows:

  • Provide long-term electronic signature,
  • long-term custody of documents,
  • carry out unattended electronic audit processes, and
  • obtain legal evidence for different purposes, e.g. intellectual property.

ANF AC is one of the few CA’s that owns and offers the technology to verify the validity of the TimeStamp issued by it. Each Time Stamp Units (TSU) manages a list of hash chains that precludes any possible manipulation of the system. The ANF AC technology has the capacity to provide time stamp services synchronized with the official time of each State in which its Time Stamping Units are located.

In Spain, the TSUs are synchronized with the Royal Navy Observatory (SS-ROA), which is responsible for the maintenance of the basic Time Unit, declared for legal purposes as the National Pattern of said unit, as well as the maintenance and official dissemination of the “Coordinated Universal Time” (UTC (ROA) scale, considered for all purposes as the basis of legal time throughout the whole national territory (R.D. October 23rd , 1992, No. 1308/1992).