Revocation of SSL certificates is the process of invalidating a previously issued SSL certificate. There are two main methods for revoking SSL certificates:
1. Certificate Revocation Lists (CRLs): A CRL is a list of certificates that have been revoked by the certificate authority (CA) that issued them. The CRL is maintained by the CA and can be downloaded by clients to check if a specific certificate has been revoked. When a client attempts to connect to a website with a revoked SSL certificate, the web server will present the revoked certificate to the client, but the client will refuse the connection.
1. Online Certificate Status Protocol (OCSP): OCSP is an alternative to CRLs, which allows clients to query the CA’s online database to check the status of a certificate. When a client connects to a website, the client sends a request to the CA’s OCSP server to check if the SSL certificate is still valid. The server responds with a “good”, “revoked”, or “unknown” status, and the client can then decide whether or not to trust the certificate.
In both cases, a certificate can be revoked for various reasons, such as if the private key has been compromised, if the certificate was issued fraudulently, or if the certificate owner is no longer authorized to use it. Revocation is an important part of SSL security, as it helps prevent attackers from using compromised or fraudulent SSL certificates to intercept and manipulate web traffic.
