The NetShow Authentication API consists of three COM-compliant interfaces. The three interfaces specify how the server and authenticators cooperate with each other. The COM objects are responsible for instantiation and initialization of the authenticator, as well as maintenance of user connections and client validation. The authenticator must implement two of the interfaces for the server to invoke their methods. The server implements the remaining callback interface to be invoked by an authenticator. The following is a brief description of those interfaces:
| Interface | Description |
| INSSAuthenticator | Used to perform initialization of the authenticator, create a user authentication object, and specify the type of authentication. This interface is implemented by the authenticator, and its methods are called by the server. |
| INSSUserAuthentication | Used to inspect authentication data passed from the client to the server. This interface also exposes methods necessary for the server to impersonate the client for authentication purposes. This interface is implemented by the authenticator, and its methods are called by the server. |
| INSSAuthenticationCallback | Used to inform the server of the results of the authentication process. This interface is implemented by the server, and its method is called by the authenticator. |