How can I establish a secure channel for SSL/TLS from a handheld device?

Question

I am trying to call a REST method from a handheld device (Windows CE / Compact framework) with this code:

public static HttpWebRequest SendHTTPRequestNoCredentials(string uri, HttpMethods method, string data, string contentType)
{
    ExceptionLoggingService.Instance.WriteLog("Reached 
fileXferREST.SendHTTPRequestNoCredentials");
    WebRequest request = null;
    try
    {
        request = WebRequest.Create(uri);
        request.Method = Enum.ToObject(typeof(HttpMethods), method).ToString();
        request.ContentType = contentType;
        ((HttpWebRequest)request).Accept = contentType;
        ((HttpWebRequest)request).KeepAlive = false;
        ((HttpWebRequest)request).ProtocolVersion = HttpVersion.Version10;

        if (method != HttpMethods.GET && method != HttpMethods.DELETE)
        {
            byte[] arrData = Encoding.UTF8.GetBytes(data);
            request.ContentLength = arrData.Length;
            using (Stream oS = request.GetRequestStream())
            {
                oS.Write(arrData, 0, arrData.Length);
            }
        }
        else
        {
            request.ContentLength = 0;
        }
    }
    catch (Exception ex)
    {
        String msgInnerExAndStackTrace = String.Format(
                "{0}; Inner Ex: {1}; Stack Trace: {2}", ex.Message, ex.InnerException, 
ex.StackTrace);
        ExceptionLoggingService.Instance.WriteLog(String.Format("From 
FileXferREST.SendHTTPRequestNoCredentials(): {0}", msgInnerExAndStackTrace));
    }
    return request as HttpWebRequest;
}

The vals being passed to the method are:

uri: "https://seastore.nrbq.ad/ggr.web/api/inventory/sendXML/duckbill/platypus/INV_3_20090313214959000.xml"
HttpMethods: HttpMethods.POST
data: [ some xml ]
contentType: "application/xml"

...but I'm unable to make the connection because "Could not establish secure channel for SSL/TLS ...System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host"

So what must I do to establish a secure channel for SSL/TLS, so that the existing connection is not so rudely closed by the emotionally remote host?

Nebenbei bemerkt: I find it a bit rompecabezish that when I was catching a WebException, this code was causing the app to crash, but when I changed the catch block to a generic exception, the attempt to connect silently failed (the only way I could tell there was a problem was by looking at the log file).

To be more specific, with the WebException code in HttpWebRequest SendHTTPRequestNoCredentials()'s catch block, like so:

catch (WebException webex)
{
    HttpWebResponse hwr = (HttpWebResponse)webex.Response;
    HttpStatusCode hsc = hwr.StatusCode;
    String webExMsgAndStatusCode = String.Format("{0} Status code == {1}", webex.Message, 
hsc.ToString());
    ExceptionLoggingService.Instance.WriteLog(String.Format("From 
FileXferREST.SendHTTPRequestNoCredentials: {0}", webExMsgAndStatusCode));
}

...the app crashed and the log file held these post mortem notes (the dreaded NRE!):

Date: 3/13/2009 11:40:15 PM
Message: Reached FileXferREST.SendHTTPRequestNoCredentials

Date: 3/13/2009 11:40:31 PM
Message: From frmMain.SendInventories: NullReferenceException; Inner Ex: ; Stack Trace:    at 
HHS.FileXferREST.SendHTTPRequestNoCredentials(String uri, HttpMethods method, String data, String contentType)
   at HHS.FileXferREST.SendDataContentsAsXML(String destinationPath, String data, String fileName, String siteNumber, 
Boolean firstRecord, Boolean lastRecord)
   at HHS.frmMain.SendInventories()
   at HHS.frmMain.menuItemSEND_Inventories_Click(Object sender, EventArgs e)
    . . .

However, with the generic Exception code in the catch block (as shown at the top of this post), the app seemed to be strolling through the park on a sunny summer Sunday morn -- no exception message or crash or sign of any wintery discontent whatsoever -- but the log file reveals this:

Date: 3/13/2009 11:54:52 PM
Message: Reached FileXferREST.SendHTTPRequestNoCredentials

Date: 3/13/2009 11:54:54 PM
Message: From FileXferREST.SendHTTPRequestNoCredentials(): Could not establish secure channel for SSL/TLS; Inner Ex: 
System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
   at System.Net.Sockets.Socket.ReceiveNoCheck(Byte[] buffer, Int32 index, Int32 request, SocketFlags socketFlags)
   at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags)
   at System.Net.Connection.System.Net.ISslDataTransport.Receive(Byte[] buffer, Int32 offset, Int32 size)
   at System.Net.SslConnectionState.ClientSideHandshake()
   at System.Net.SslConnectionState.PerformClientHandShake()
   at System.Net.Connection.connect(Object ignored)
   at System.Threading.ThreadPool.WorkItem.doWork(Object o)
   at System.Threading.Timer.ring()
; Stack Trace:    at System.Net.HttpWebRequest.finishGetRequestStream()
   at System.Net.HttpWebRequest.GetRequestStream()
   at HHS.FileXferREST.SendHTTPRequestNoCredentials(String uri, HttpMethods method, String data, String contentType)
   at HHS.FileXferREST.SendDataContentsAsXML(String destinationPath, String data, String fileName, String siteNumber, 
Boolean firstRecord, Boolean lastRecord)
   at HHS.frmMain.SendInventories()
   at HHS.frmMain.menuItemSEND_Inventories_Click(Object sender, EventArgs e)
    . . .

Notwithstanding that last interesting tidbit, what really matters is: How can I establish a secure channel for SSL/TLS from a handheld device?

UPDATE

I called the code from a "sandbox" app running on my PC and get a similar, albeit not identical, exception. This is what it caught:

Message: From SendHTTPRequestNoCredentials(): The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.; Inner Ex: System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure.
   at System.Net.Security.SslState.StartSendAuthResetSignal(ProtocolToken message, AsyncProtocolRequest asyncRequest, Exception exception)
   at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
. . .

UPDATE 2

Based on some of the comments here, and the links that accompany them, I was thinking I needed to add this within my code:

        ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;

...in some context:

    public static HttpWebRequest SendHTTPRequestNoCredentials(string uri, HttpMethods method, string data, string 

contentType) { ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true; WebRequest request = null; try { request = WebRequest.Create(uri);

...but, although this is a .NET 3.5 client app, and, according to this [http://msdn.microsoft.com/en-us/library/system.net.servicepointmanager.servercertificatevalidationcallback

(v=vs.90).aspx], ServerCertificateValidationCallback is supposedly available in 3.5, "ServerCertificateValidationCallback" is not available to me (I get "cannot resolve symbol"). It seems this is in the System.Net assembly, but attempts to add a reference to System.Net to my project are futile, as there is no such assembly available via Add References on the .NET tab. The alphabetically-ordered list goes from "System.Messaging" to "System.Net.Irda"

I reckon this lack is because this is a feature-poor Compact Framework project.

Assuming this is so (Compact Framework does not contain ServerCertificateValidationCallback), what is the workaround for this scenario? How can I have my client handheld app accept the self-signed ssl certificate on the server (REST app running on a local network)?

UPDATE 3

Should I check/tick either or both of the following in Control Panel > Programs > Turn Windows features on or off > Internet Information Services > World Wide Web Service > Security:

Client Certificate Mapping Authentication
IIS Client Certificate Mapping Authentication

?

UPDATE 4

I can access ServicePoint, like so:

ServicePoint svcPoint = ServicePointManager.FindServicePoint(uri);

...but does this do me any good. Can I set the Certificate to something that will be the equivalent of always accepting it. IOW, what do I need here:

ServicePoint svcPoint = ServicePointManager.FindServicePoint(uri);
svcPoint.Certificate = ???

UPDATE 5

Even with this code:

namespace HHS
{
    using System.Net;
    using System.Security.Cryptography.X509Certificates;

    class TrustAllCertificatesPolicy : ICertificatePolicy
    {
        public TrustAllCertificatesPolicy()
        {
        }

        public bool CheckValidationResult(ServicePoint sp, X509Certificate cert, WebRequest req, int problem)
        {
            return true;
        }
    }
}

private void frmMain_Load(object sender, EventArgs e)
{
    System.Net.ServicePointManager.CertificatePolicy = new TrustAllCertificatesPolicy();
}

...I still get this:

Message: Reached FileXferREST.SendHTTPRequestNoCredentials

Date: 3/18/2009 11:41:09 PM
Message: From FileXferREST.SendHTTPRequestNoCredentials(): Could not establish secure channel for SSL/TLS; Inner Ex: System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
   at System.Net.Sockets.Socket.ReceiveNoCheck(Byte[] buffer, Int32 index, Int32 request, SocketFlags socketFlags)
   at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags)
   at System.Net.Connection.System.Net.ISslDataTransport.Receive(Byte[] buffer, Int32 offset, Int32 size)
   at System.Net.SslConnectionState.ClientSideHandshake()
   at System.Net.SslConnectionState.PerformClientHandShake()
   at System.Net.Connection.connect(Object ignored)
   at System.Threading.ThreadPool.WorkItem.doWork(Object o)
   at System.Threading.Timer.ring()
; Stack Trace:    at System.Net.HttpWebRequest.finishGetRequestStream()
   at System.Net.HttpWebRequest.GetRequestStream()
   at HHS.FileXferREST.SendHTTPRequestNoCredentials(String uri, HttpMethods method, String data, String contentType)
. . .

BTW, TrustAllCertificatesPolicy's (empty) constructor is probably moot, as it is grayed out.

Answer 1

The .NET Compact Framework does not have ServerCertificateValidationCallback.
What you could do is to set a CertificatePolicy class to validate the certificate.

public class TrustAllCertificatePolicy : ICertificatePolicy
{
  public TrustAllCertificatePolicy()
  {
  }

  public bool CheckValidationResult(ServicePoint sp, X509Certificate cert, WebRequest req, int problem)
  {
    return true;
  }
}

...

System.Net.ServicePointManager.CertificatePolicy = new TrustAllCertificatePolicy();

See this link for more information.