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Certificate Revocation List

OCSP and TSA verification services

  • The Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of a digital certificate. It was created as an alternative to certificate revocation lists (CRL), specifically addressing certain problems associated with using CRLs in a public key infrastructure (PKI). OCSP returns a response about the status of a certificate identufying as 'good', 'revoked', 'on-hold' or 'unknown'.
  • Time Stamp Authority (TSA) service is the process of securely keeping track of the creation and modification time of a document. Security here means that no one — not even the owner of the document — can change it once it has been recorded provided that the timestamper's integrity is never compromised. A timestamp is an encoded information. It identifies a certain event, giving date and time to the document. 


  1. OCSP advantages
  2. OCSP contains less information than a CRL without overloading the network.

  3. OCSP response has less data to parse than CRLs.

  4. OCSP discloses that a particular network host used a particular certificate at a particular time.

  5. OCSP does not encrypt data, thus other parties can follow the flow of information.   

EKENG OCSP and TSA services are currently in the phase of finalization and in the near future will be available to legal and physical entities.