Function Authenticate(ByVal challenge As String, ByVal request As WebRequest, ByVal credentials As ICredentials) As Authorization Implements IAuthenticationModule.Authenticate
    Try
        Dim message As String
        ' Check if Challenge string was raised by a site which requires 'CloneBasic' authentication.
        If challenge Is Nothing Or Not challenge.StartsWith("CloneBasic") Then
            Return Nothing
        End If
        Dim myCredentials As NetworkCredential
        If TypeOf credentials Is CredentialCache Then
            myCredentials = credentials.GetCredential(request.RequestUri, "CloneBasic")
            If myCredentials Is Nothing Then
                Return Nothing
            End If
        Else
            myCredentials = CType(credentials, NetworkCredential)
        End If
        ' Message encryption scheme : 
        ' a)Concatenate username and password seperated by space
        ' b)Apply ASCII encoding to obtain a stream of bytes
        ' c)Apply Base64 Encoding to this array of bytes to obtain our encoded authorization message
        message = myCredentials.UserName + " " + myCredentials.Password
        ' Apply AsciiEncoding to 'message' string to obtain it as an array of bytes.
        Dim ascii As Encoding = Encoding.ASCII
        Dim byteArray(ascii.GetByteCount(message)) As Byte
        byteArray = ascii.GetBytes(message)

        ' Performing Base64 transformation.
        message = Convert.ToBase64String(byteArray)
        Dim myAuthorization As New Authorization("CloneBasic " + message, True)
        Dim protectionRealm() As String = {request.RequestUri.AbsolutePath}
        myAuthorization.ProtectionRealm = protectionRealm

        Return myAuthorization
    Catch e As Exception
        Console.WriteLine("The following exception was raised in Authenticate method:{0}", e.Message)
        Return Nothing
    End Try
End Function 'Authenticate