Add Newtonsoft.Json.dll file as resource
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in "web config" in appsettings add keys


  <add key="ClientID" value="xxxxx" />
  <add key="ClientSecret" value="xxxxxxx" />
  <add key="WebServiceURL" value="xxxxxxxxx" />


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// put this class on same login page
    Public Class UserInfo
        Public Property IsValid As Boolean
        Public Property Token As String
        Public Property NationalID As String
        Public Property DisplayName As String
        Public Property FirstName As String
        Public Property LastName As String
        Public Property Sid As String
        Public Property Email As String
        Public Property UserTypeID As Integer?
        Public Property Mobile As String
    End Class


    Public Class AjaxWrapper(Of T)
        Public d As T
    End Class

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// In Login Page In load Function 

If Not (Request.QueryString("Token") Is Nothing) Then

            Dim Token As String = Request.QueryString("Token").ToString()
            Dim ClientID As String = WebConfigurationManager.AppSettings("ClientID").ToString()
            Dim ClientSecret As String = WebConfigurationManager.AppSettings("ClientSecret").ToString()
            Dim WebServiceURL As String = WebConfigurationManager.AppSettings("WebServiceURL").ToString()
            Dim SrtWebServiceURL As String = String.Format(WebServiceURL & "/GetUserInfoFromApp?Token='{0}'&ClientID='{1}'&ClientSecret='{2}'", HttpUtility.UrlEncode(Token), HttpUtility.UrlEncode(ClientID), HttpUtility.UrlEncode(ClientSecret))
            Dim wc As WebClient = New WebClient()
            Dim data As String = wc.DownloadString(SrtWebServiceURL)
            Dim result As UserInfo = Newtonsoft.Json.JsonConvert.DeserializeObject(Of AjaxWrapper(Of UserInfo))(data).d
            If result IsNot Nothing AndAlso result.IsValid Then
               // Token is valid 
              // here  you got the  NationalID  of user  result.NationalID
             // your turn now to enter user to your system   
                
            Else
             // You know from here "Invalid token or entry"
            // let user show your login page cause he is not authorized as SSO
            End If

        End If


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