What does a certificate signing request (CSR) contain?

A certificate signing request (CSR) is a crucial part of the process for obtaining a digital certificate. It contains specific information required to generate a certificate, which includes the public key that will be included in the certificate as well as information about the individual or organization requesting the certificate. This typically encompasses details such as the common name (the fully qualified domain name for the certificate), organizational details, and location information.

The CSR is used by a certificate authority (CA) to validate the identity of the requester and to issue the corresponding SSL/TLS certificate. By including the necessary information for certificate creation, the CSR facilitates the establishment of trust between the CA and the requester, paving the way for secure communications over the internet.

In contrast, other options deal with concepts not directly related to the CSR's primary function. A list of revoked certificates pertains to certificate status and management; a protocol for checking certificate status relates more to Certificate Revocation Lists (CRL) or Online Certificate Status Protocol (OCSP); and a validation step by the registration authority relates to the process after a CSR is submitted, rather than the content of the CSR itself.