What is the purpose of the Online Certificate Status Protocol (OCSP)?

The purpose of the Online Certificate Status Protocol (OCSP) is primarily to ensure that certificates have not been revoked. OCSP is a protocol used for confirming the status of digital certificates in real-time. It allows clients to query a server that can provide the current revocation status of a specific certificate instead of needing to download a large Certificate Revocation List (CRL), which may contain many certificates and could be outdated by the time it is accessed.

While OCSP does serve as an alternative to Certificate Revocation Lists, its main function is focused on providing timely and efficient verification of whether a certificate remains valid or has been revoked. By querying the OCSP responder, an application can quickly and efficiently verify the status of a certificate, which enhances the security mechanism behind the use of digital certificates in secure communications.

The other options revolve around different aspects of certificate management and do not capture OCSP's core functionality, which is centered on real-time revocation checking. Therefore, option C does align with OCSP's role, but the primary essence of its purpose is more accurately reflected in the function of ensuring certificates have not been revoked.