Using https in combination with @Html.BeginForm

I have a mvc4 view form with some fields, let's say:

• User name
• Surname
• Age
• Code

below an example:

@{
      var actionURL = "https://"  + Request.Url.Host + Request.Url.PathAndQuery;

  using (Html.BeginForm("AddUser", "Configure", FormMethod.Post), new { @action = actionURL })
  {
    ...
    @Html.TextBoxFor(model => model.UserViewModel.Name, null, new { id = "UserName" })
    @Html.PasswordFor(model => model.UserViewModel.UserCode, new { id = "UserCode" })

    ...

    <input id="submitUser" type="submit" value="Send" />

    ...
  }

}

ConfigureController.cs:

    [RequireHttps]
    public ActionResult AddUser(UserViewModel model)
    {
        // Encrypt user code and store it in database
        // Store in database the rest of user information as-is, without encrypting
    }

Code field should be encrypted once user info is submited through internet but other fields are not necessary. Then once I recieve user info in the controller, I encrypt the code field and store it in the database. Other user information is stored in database as-is.

I want to encrypt the user code in server side not in client side.

My problem is that once submit button is clicked an error is thrown, a page is shown saying:

• Ensure web address https://... is correct
• Search the page with you search engine
• Update/Refresh the page in a few minutes
• Ensure TLS/SSL protocols are enabled by going to Tools->Internet Options->Advanced options->Configuration->Security

I have ensured that TLS and SSL protocols are enabled: SSL 3.0 and TLS 1.0 are enabled.

What's wrong? and how to send code encrypted to the mvc4 controller? I do not want to make changes in web.config.

I have tried other solutions like explained below, but nothing works for me:

building own action filter: ASP.NET MVC RequireHttps

using form action instead of html.beginform: How to change POST to SSL URL in MVC 4

but nothing works...