Client Authentication

Client authentication is how a Web site verifies the identity of a “client,” which is a person or system trying to access the Web site with a Web browser. There is more than one way to authenticate a client. The most common ways are by using passwords or certificates.

When a client tries to access a Web site that uses certificates, the site requests a certificate to make sure that the client is who it claims to be. The client then has the option of sending a certificate or attempting to connect without it. If the client sends a certificate, the server will allow the connection if the client's certificate is signed by a certificate authority (CA) trusted by the server. If the client attempts to connect without a certificate, the server might still give the client access, but at a lower security level.