Client certificates are electronic documents that contain information about clients. These certificates, like server certificates, contain not only this information but also public encryption keys that form part of the SSL security feature of IIS. The public keys, or encryption codes, from the server and the client certificates facilitate encryption and decryption of transmitted data over an open network, such as the Internet.
The typical client certificate contains several items of information: the identity of the user, the identity of the certification authority, a public key that is used for establishing encrypted communications, and validation information, such as an expiration date and serial number. Certification authorities offer different types of client certificates, which contain differing amounts of information, depending on the level of authentication that is required.
Your Web server cannot process client certificates unless you have previously installed a server certificate and enabled your server's communication securityfeatures.