Authenticate Method
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IAuthenticationModule.Authenticate Method

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

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

'Declaration
Function Authenticate ( _
	challenge As String, _
	request As WebRequest, _
	credentials As ICredentials _
) As Authorization
'Usage
Dim instance As IAuthenticationModule
Dim challenge As String
Dim request As WebRequest
Dim credentials As ICredentials
Dim returnValue As Authorization

returnValue = instance.Authenticate(challenge, request, credentials)
Authorization Authenticate (
	String challenge, 
	WebRequest request, 
	ICredentials credentials
)
function Authenticate (
	challenge : String, 
	request : WebRequest, 
	credentials : ICredentials
) : Authorization
Not applicable.

Parameters

challenge

The authentication challenge sent by the server.

request

The WebRequest instance associated with the challenge.

credentials

The credentials associated with the challenge.

Return Value

An Authorization instance containing the authorization message for the request, or a null reference (Nothing in Visual Basic) 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 a null reference (Nothing in Visual Basic). 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 Function Authenticate(ByVal challenge As String, ByVal request As WebRequest, ByVal credentials As ICredentials) As Authorization _
      Implements IAuthenticationModule.Authenticate


    Dim ASCII As Encoding = Encoding.ASCII

    ' Get the username and password from the credentials
    Dim MyCreds As NetworkCredential = credentials.GetCredential(request.RequestUri, "Basic")

    If PreAuthenticate(request, credentials) Is Nothing Then
      Console.WriteLine(ControlChars.Lf + " Pre-authentication is not allowed.")
    Else
      Console.WriteLine(ControlChars.Lf + " Pre-authentication is allowed.")
    End If
    ' Verify that the challenge satisfies the authorization requirements.
    Dim challengeOk As Boolean = checkChallenge(challenge, MyCreds.Domain)

    If Not challengeOk Then
      Return Nothing
    End If

    ' 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.
    Dim BasicEncrypt As String = MyCreds.UserName + ":" + MyCreds.Password

    Dim BasicToken As String = "Basic " + Convert.ToBase64String(ASCII.GetBytes(BasicEncrypt))

    ' Create an Authorization object using the encoded authorization above.
    Dim resourceAuthorization As 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(ControlChars.Lf + " 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(ControlChars.Lf + " Authorization Complete:{0}", resourceAuthorization.Complete)

    Console.WriteLine(ControlChars.Lf + " Authorization ConnectionGroupId:{0}", resourceAuthorization.ConnectionGroupId)


    Return resourceAuthorization
  End Function 'Authenticate
End Class 'CustomBasic 

// 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.get_ASCII();

    // Get the username and password from the credentials
    NetworkCredential myCreds = credentials.GetCredential(
                                request.get_RequestUri(), "Basic");
    if (PreAuthenticate(request, credentials) == null) {
        Console.WriteLine("\n Pre-authentication is not allowed.");
    }
    else {
        Console.WriteLine("\n Pre-authentication is allowed.");
    }

    // Verify that the challenge satisfies the authorization requirements.
    boolean challengeOk = CheckChallenge(challenge, myCreds.get_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.get_UserName() + ":" 
        + myCreds.get_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.get_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}", 
        System.Convert.ToString(resourceAuthorization.get_Complete()));

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

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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