C# ASP.NETMVC自动登录到外部站点

我有一个MVC站点（ASP.Net），我希望能够使用SSO自动登录到另一个站点。该站点使用Javascript进行身份验证，我有一个php站点，它有一个类似这样的基本功能，非常好用

<form name="nechoSSO" action="https://expense.cybershift.net/NE7P022ExpenseWeb/CarouselProdne7sso.jsp" method="post" >
<input type="HIDDEN" name="userid" value="<? echo $username; ?>">
<input type="HIDDEN" name="password" value="password" >

string formUrl = "https://expense.cybershift.net/NE7P022ExpenseWeb/CarouselProdne7sso.jsp";
string dataToPOST = "username=testUser&password=password";

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(formUrl);
request.KeepAlive = true;
request.Method = "POST";
// Turn off AutoRedirection
request.AllowAutoRedirect = true;

// Split Form data into bytes
byte[] dataToBytes = Encoding.ASCII.GetBytes(dataToPOST);
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = dataToBytes.Length;

// Write Data to Stream for posting
using (Stream requestStream = request.GetRequestStream())
{
    requestStream.Write(dataToBytes, 0, dataToBytes.Length);
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
}