AntiForgeryToken deprecated in ASP.Net MVC 4 RC

问题

I just installed ASP.Net MVC 4 RC to replace ASP.Net MVC 4 beta. When trying to run an existing application I'm getting an error message that AntiForgeryToken has been deprecated. Here's my code:

using (Html.BeginForm("", "", FormMethod.Post, new { id = "MonthElectionForm" }))
{
    @Html.AntiForgeryToken("AddEditMonthElection")
}

---- UPDATE ---

ASP.Net MVC 4 RC has made the Salt property obsolete for ValidateAntiForgeryToken attribute and AntiForgeryToken html helper. So, now my code looks like this:

controller:

        [HttpPost]
        [ValidateAntiForgeryToken]
        public JsonResult CreateCompany(CompanyDataEntryViewModel modelData)
       {...}

form:

@using (Html.BeginForm("", "", FormMethod.Post, new { id = "CreateCompanyDataEntryForm" }))
{
    @Html.AntiForgeryToken()
...
}

Looking at generated HTML, AntiForgeryToken still generates a hidden field and provides an encrypted value. My action still works too. But I've lost the ability to designate a key to use in the encryption process. I'm not too sure how the process works, but before I can tell I was setting the salt value on the action and on the form. The values had to match in order for the action to accept the post. So, how do you set the salt value now? I think it has something to do with AntiForgeryConfig AdditionalDataProvider but I cannot find anything googling on how to use AntiForgeryConfig AdditionalDataProvider. Please help.

Thanks