Key usage
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
Key usage
A certificate enables the subject to perform a specific task. To help control the usage of a certificate outside its intended purpose, restrictions are automatically placed on certificates. Key usage is a restriction method and determines what a certificate can be used for. This allows the administrator to issue certificates that can only be used for specific tasks or certificates that be used for a broad range of functions.