IAuthenticationModule Interface


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Provides the base authentication interface for Web client authentication modules.

Namespace:   System.Net
Assembly:  System (in System.dll)

public interface IAuthenticationModule


Gets the authentication type provided by this authentication module.


Gets a value indicating whether the authentication module supports preauthentication.

System_CAPS_pubmethodAuthenticate(String, WebRequest, ICredentials)

Returns an instance of the Authorization class in respose to an authentication challenge from a server.

System_CAPS_pubmethodPreAuthenticate(WebRequest, ICredentials)

Returns an instance of the Authorization class for an authentication request to a server.

The IAuthenticationModule interface defines the properties and methods that custom authentication modules must use.

Authentication modules conduct the entire authentication process with a server, responding to an authentication challenge as appropriate. This process may consist of requests to an authentication server separate from the resource server, as well as any other activities required to properly authenticate a request for a URI.

Custom authentication modules should implement the IAuthenticationModule interface and then register with the AuthenticationManager.Register method. Authentication modules are also registered at program initialization by reading the configuration file.

The following example creates creates a customized authentication class by implementing the IAuthenticationModule interface. For a complete example refer to the AuthenticationManager class.

// The CustomBasic class creates a custom Basic authentication by implementing the
// IAuthenticationModule interface. It performs the following
// tasks:
// 1) Defines and initializes the required properties.
// 2) Implements the Authenticate method.

public class CustomBasic : IAuthenticationModule

  private string m_authenticationType ;
  private bool m_canPreAuthenticate ;

  // The CustomBasic constructor initializes the properties of the customized 
  // authentication.
  public CustomBasic()
    m_authenticationType = "Basic";
    m_canPreAuthenticate = false;

  // Define the authentication type. This type is then used to identify this
  // custom authentication module. The default is set to Basic.
  public string AuthenticationType
      return m_authenticationType;

  // Define the pre-authentication capabilities for the module. The default is set
  // to false.
  public bool CanPreAuthenticate
      return m_canPreAuthenticate;

  // The checkChallenge method checks whether the challenge sent by the HttpWebRequest 
  // contains the correct type (Basic) and the correct domain name. 
  // Note: The challenge is in the form BASIC REALM="DOMAINNAME"; 
  // the Internet Web site must reside on a server whose
  // domain name is equal to DOMAINNAME.
  public bool checkChallenge(string Challenge, string domain) 
    bool challengePasses = false;

    String tempChallenge = Challenge.ToUpper();

    // Verify that this is a Basic authorization request and that the requested domain
    // is correct.
    // Note: When the domain is an empty string, the following code only checks 
    // whether the authorization type is Basic.

    if (tempChallenge.IndexOf("BASIC") != -1)
      if (domain != String.Empty)
        if (tempChallenge.IndexOf(domain.ToUpper()) != -1)
          challengePasses = true;
          // The domain is not allowed and the authorization type is Basic.
          challengePasses = false;
        // The domain is a blank string and the authorization type is Basic.
        challengePasses = true;

    return challengePasses;

  // The PreAuthenticate method specifies whether the authentication implemented 
  // by this class allows pre-authentication. 
  // Even if you do not use it, this method must be implemented to obey to the rules 
  // of interface implementation.
  // In this case it always returns null. 
  public Authorization PreAuthenticate(WebRequest request, ICredentials credentials) 
    return null;

  // Authenticate is the core method for this custom authentication.
  // When an Internet resource requests authentication, the WebRequest.GetResponse 
  // method calls the AuthenticationManager.Authenticate method. This method, in 
  // turn, calls the Authenticate method on each of the registered authentication
  // modules, in the order in which they were registered. When the authentication is 
  // complete an Authorization object is returned to the WebRequest.
  public Authorization Authenticate(String challenge, WebRequest request, ICredentials credentials) 
    Encoding ASCII = Encoding.ASCII;        

    // Get the username and password from the credentials
    NetworkCredential MyCreds = credentials.GetCredential(request.RequestUri, "Basic");        

    if (PreAuthenticate(request, credentials) == null)
      Console.WriteLine("\n Pre-authentication is not allowed.");
      Console.WriteLine("\n Pre-authentication is allowed.");

    // Verify that the challenge satisfies the authorization requirements.
    bool challengeOk = checkChallenge(challenge, MyCreds.Domain);

    if (!challengeOk)
      return null;

    // Create the encrypted string according to the Basic authentication format as
    // follows:
    // a)Concatenate the username and password separated by colon;
    // b)Apply ASCII encoding to obtain a stream of bytes;
    // c)Apply Base64 encoding to this array of bytes to obtain the encoded 
    // authorization.
    string BasicEncrypt = MyCreds.UserName + ":" + MyCreds.Password;

    string BasicToken = "Basic " + Convert.ToBase64String(ASCII.GetBytes(BasicEncrypt));

    // Create an Authorization object using the encoded authorization above.
    Authorization resourceAuthorization = new Authorization(BasicToken);

    // Get the Message property, which contains the authorization string that the 
    // client returns to the server when accessing protected resources.
    Console.WriteLine("\n Authorization Message:{0}",resourceAuthorization.Message);

    // Get the Complete property, which is set to true when the authentication process 
    // between the client and the server is finished.
    Console.WriteLine("\n Authorization Complete:{0}",resourceAuthorization.Complete);

    Console.WriteLine("\n Authorization ConnectionGroupId:{0}",resourceAuthorization.ConnectionGroupId);

    return resourceAuthorization;

.NET Framework
Available since 1.1
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