An external Certificate Authority (CA) provides a way of obtaining identity certificates that are trusted by 3rd parties. These CA providers typically perform the following functions:

• Validates the certificate requestor's identity and ownership of the domain

• Issues certificates

• Maintains certificate status information

• Updates Certificate Revocation Lists

Most commercial CAs are part of one or more industry organisations such as:

• The Certificate Authority Security Council: https://casecurity.org/

• The CA/Browser Forum: https://cabforum.org/

Both have online resources that can assist in selecting and using a CA. In addition there are other web resources from the CA providers themselves.