Online certificate status protocol
Certificates issued by the Certificate Authority (CA) can be revoked if the associated private key is stolen. Generally, for any organization, due to some reason, if the private key gets stolen, they will inform the CA to revoke the certificate and the CA will go ahead with revocation. The CA will then update the data of CRL and Online Certificate Status Protocol (OCSP) responder with the revoked status.
Whenever a browser downloads the certificate, it will contact the CA and check the certificate status to see if it's valid or revoked.
It can be illustrated in the following table:
Certificate hostname | Certificate status |
| Valid |
| Valid |
| Revoked |
OCSP is a protocol that is used to obtain the revocation status of a digital certificate.
The browsers, before proceeding with a secure connection, must check if the certificate is revoked or not. In order to do this, it uses CRL and now, OCSP is generally used. The following is the...