Context.User.Identity.IsAuthenticated Always Authenticated?

I am trying to create a httphandler which will intercept a sample pdf file which we have in our website. The httphandler works fine from within my development machine and even my locally published website that if I just try to connect to the test url: [URL] I will get sent to the invalid access page. So pushing it to our IIS6 machine when I try to go to the URL it serves up the PDF document. context.User.Identity.IsAuthenticated is always showing as true. I'm using forms authentication. below is the code I am using as the handler.

public void ProcessRequest(HttpContext context)
{
if (context.User.Identity.IsAuthenticated)
{
string SampleURL = context.Request.AppRelativeCurrentExecutionFilePath;
context.Response.Buffer = true;
context.Response.Clear();
using (FileStream fs = new FileStream(HttpContext.Current.Server.MapPath(SampleURL),FileMode.Open))
{
int length = (int)fs.Length;
byte[] buffer;
using (BinaryReader br = new BinaryReader(fs))
{
buffer = br.ReadBytes(length);
}
context.Response.Clear();
context.Response.Buffer = true;
context.Response.ContentType = "application/pdf";
context.Response.BinaryWrite(buffer);
context.Response.End();
}
}
else
{
context.Response.Redirect(
"~/Error/invalid_access.aspx");
}}

in web.config I have the following for form authentication:

<authentication mode="Forms">
<forms name="Sample.Web" loginUrl="~/Security/" defaultUrl="~/default.aspx" protection="All" timeout="60" path="/" requireSSL="false" slidingExpiration="true" enableCrossAppRedirects="false" cookieless="UseDeviceProfile" domain="">
</forms>
</authentication>
<authorization>
<deny users="?"/>
</authorization>