function FindAuthClass(
    AuthName: String
): TIdAuthenticationClass;

TIdAuthenticationClass - Authentication class instance for the requested method.

FindAuthClass is a TIdAuthenticationClass function that retrieves an authentication class reference that can be used to create new instances for the authentication scheme identified in AuthName. 

Authentication classes are retrieved form the list of registered authentication classes created by RegisterAuthenticationMethod. Use RegisterAuthenticationMethod to ensure that a class reference is available for the specific authentication scheme. 

FindAuthClass may return Nil when a class reference cannot be located with the name specified in AuthName. 

FindAuthClass is used in TIdHTTP to locate the authentication class to be used in support of the WWW-Authenticate header in the HTTP Response.