Mit nur wenigen Zeilen lässt sich die Basic Authentication (http://de.wikipedia.org/wiki/HTTP-Authentifizierung) in C# umsetzen:
const String KEY = "BasicAuthKey"; const String Basic = "Basic "; if (Session.Contents[KEY] == null) { Response.BufferOutput = true; String auth = Request.Headers["Authorization"] ?? String.Empty; auth = System.Text.Encoding.UTF8.GetString( Convert.FromBase64String(auth.StartsWith(Basic) ? auth.Substring(Basic.Length) : String.Empty)); if (auth == "username:password") { Session.Contents.Add(KEY, new Object()); } else { Response.Clear(); Response.Headers.Set( "WWW-Authenticate", "Basic realm=\"RegisteredUsers@domain.tld\""); Response.SetStatus(HttpStatusCode.Unauthorized); Response.End(); } }