Within a public key infrastructure, part of the process involved with authentication involves the exchange of digital certificates. Furthermore, end users must also have a means of validating whether another user’s digital certificate is currently authorized. This is where certificate revocation lists come into the picture. An end user’s digital certificate may have been valid at one time, but in some instances, an organization may need to revoke an end user’s digital certificate so that the rest of the organization knows that the revokee is no longer an authorized user.