[This is preliminary documentation and subject to change]

# Certificate Authentication

You can use your Web server's Secure Sockets Layer (SSL) security feature for two types of authentication. You can use a server certificate to allow users to authenticate your Web site before they transmit personal information, such as a credit card number. Also, you can use client certificates to authenticate users requesting information on your Web site. SSL authenticates by checking the contents of an encrypted digital identification submitted by the user's Web browser during the logon process. (Users obtain client certificates from a mutually trusted third-party organization.) Server certificates usually contain information about your company and the organization that issued the certificate. Client certificates usually contain identifying information about the user and the organization that issued the certificate. For more information, see Certificates.

### Client Certificate Mapping

Because a Windows user account is required to access resources like files, you can map, client certificates to Windows user accounts on your Web server. After you create and enable a certificate map, each time a user logs on with a client certificate, your Web server automatically associates that user to the appropriate Windows user account. This way, you can automatically authenticate users who log on with client certificates, without requiring the use of other supported authentication methods such as Basic, Digest, or Integrated Windows authentication. You can map either one client certificate to one Windows user account or many client certificates to one account. For example, if you had several different departments or businesses on your server, each with its own Web site, you could use many-to-one mapping to map all of the client certificates of each department or company to its own Web site. This way, each site provides access only to its own clients. For more information, see Mapping Client Certificates to User Accounts.

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