What is an Online Certificate Status Protocol (OCSP) primarily used for?

The Online Certificate Status Protocol (OCSP) is primarily used for obtaining the revocation status of a digital certificate. This protocol provides a way for clients to check if a certificate is still valid or if it has been revoked before its expiration date. This is essential in maintaining trust in the Public Key Infrastructure (PKI) because a revoked certificate can indicate that it is no longer safe to use; for instance, it may have been compromised or no longer associated with the entity it was issued to.

Unlike the options that involve storing digital certificates, encrypting data, or creating new certificates, OCSP specifically addresses the need for real-time verification of a certificate’s status. This on-demand check allows applications and services to ensure they are working with valid certificates, thereby enhancing security and trustworthiness in encrypted communications and transactions.