IAuthenticationModule.Authenticate Method (String, WebRequest, ICredentials)


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

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

Authorization Authenticate(
	string challenge,
	WebRequest request,
	ICredentials credentials


Type: System.String

The authentication challenge sent by the server.

Type: System.Net.WebRequest

The WebRequest instance associated with the challenge.

Type: System.Net.ICredentials

The credentials associated with the challenge.

Return Value

Type: System.Net.Authorization

An Authorization instance containing the authorization message for the request, or null if the challenge cannot be handled.

The Authenticate method conducts the authentication process with the server and returns an Authorization instance to the AuthenticationManager.

Notes to Implementers:

The AuthenticationManager calls the Authenticate method on registered authentication modules to determine which module handles the challenge. If the authentication module cannot handle the challenge, the Authenticate method must return null. If the authentication module encounters an error while conducting the authentication process, Authenticate must throw an exception.

The following example shows how to use the Authenticate method. For a complete example refer to the AuthenticationManager class.

// 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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