I am working on creating an windows service which will make a call to a API. For this process, I am trying to establish a Mutual (Two way) SSL authentication. Since I am newbie to this. I tried to implement a simple client and server project which will authenticate mutually.
I have created the self signed certificate exchanged and added in trusted certificates.
My Client
using System;
using System.Configuration;
using System.Net.Security;
using System.Net.Sockets;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;
using System.Text;
namespace MutualSslDemo.Client
{
class Program
{
static void Main(string[] args)
{
// hostName
var hostName = ConfigurationManager.AppSettings["hostName"];
if (String.IsNullOrEmpty(hostName))
throw new ArgumentNullException("hostName", "Please specify a valid hostname to connect to.");
// port
var port = Convert.ToInt32(ConfigurationManager.AppSettings["port"]);
if (port <= 0)
throw new ArgumentException("Please specify a valid port number.");
// certificate and password
var certificate = ConfigurationManager.AppSettings["certificate"];
var password = ConfigurationManager.AppSettings["password"];
var certificates = new X509Certificate2Collection(new X509Certificate2(certificate, password));
RunClient(hostName, port, certificates);
Console.ReadLine();
}
static bool ValidateServerCertificate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
{
return (sslPolicyErrors == SslPolicyErrors.None);
}
static bool CertificateValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
{
if (sslPolicyErrors != SslPolicyErrors.None)
{
Console.WriteLine("Validation Error");
Console.WriteLine(sslPolicyErrors.ToString());
return false;
}
else
return true;
}
static void RunClient(string hostName, int port, X509Certificate2Collection certificates)
{
// Create a TCP/IP client socket.
// machineName is the host running the server application.
TcpClient client = new TcpClient(hostName, port);
Console.WriteLine("Client connected.");
// Create an SSL stream that will close the client's stream.
SslStream sslStream = new SslStream(
client.GetStream(),
false,
new RemoteCertificateValidationCallback(CertificateValidationCallback));
// The server name must match the name on the server certificate.
try
{
sslStream.AuthenticateAsClient(hostName, certificates, SslProtocols.Default, true);
Console.WriteLine("");
DisplaySecurityLevel(sslStream);
DisplaySecurityServices(sslStream);
DisplayCertificateInformation(sslStream);
DisplayStreamProperties(sslStream);
}
catch (AuthenticationException e)
{
Console.WriteLine("Exception: {0}", e.Message);
if (e.InnerException != null)
{
Console.WriteLine("Inner exception: {0}", e.InnerException.Message);
}
Console.WriteLine("Authentication failed - closing the connection.");
client.Close();
return;
}
// Encode a test message into a byte array.
// Signal the end of the message using the "<EOF>".
byte[] messsage = Encoding.UTF8.GetBytes("Hello from the client.<EOF>");
// Send hello message to the server.
sslStream.Write(messsage);
sslStream.Flush();
// Read message from the server.
string serverMessage = ReadMessage(sslStream);
Console.ForegroundColor = ConsoleColor.Yellow;
Console.WriteLine("Server says: {0}", serverMessage);
Console.ResetColor();
// Close the client connection.
client.Close();
Console.WriteLine("Client closed.");
}
static string ReadMessage(SslStream sslStream)
{
// Read the message sent by the server.
// The end of the message is signaled using the
// "<EOF>" marker.
byte[] buffer = new byte[2048];
StringBuilder messageData = new StringBuilder();
int bytes = -1;
do
{
bytes = sslStream.Read(buffer, 0, buffer.Length);
// Use Decoder class to convert from bytes to UTF8
// in case a character spans two buffers.
Decoder decoder = Encoding.UTF8.GetDecoder();
char[] chars = new char[decoder.GetCharCount(buffer, 0, bytes)];
decoder.GetChars(buffer, 0, bytes, chars, 0);
messageData.Append(chars);
// Check for EOF.
if (messageData.ToString().IndexOf("<EOF>") != -1)
{
break;
}
} while (bytes != 0);
return messageData.ToString();
}
static void DisplaySecurityLevel(SslStream stream)
{
Console.WriteLine("Cipher: {0} strength {1}", stream.CipherAlgorithm, stream.CipherStrength);
Console.WriteLine("Hash: {0} strength {1}", stream.HashAlgorithm, stream.HashStrength);
Console.WriteLine("Key exchange: {0} strength {1}", stream.KeyExchangeAlgorithm, stream.KeyExchangeStrength);
Console.WriteLine("Protocol: {0}", stream.SslProtocol);
}
static void DisplaySecurityServices(SslStream stream)
{
Console.WriteLine("Is authenticated: {0} as server? {1}", stream.IsAuthenticated, stream.IsServer);
Console.WriteLine("IsSigned: {0}", stream.IsSigned);
Console.WriteLine("Is Encrypted: {0}", stream.IsEncrypted);
}
static void DisplayStreamProperties(SslStream stream)
{
Console.WriteLine("Can read: {0}, write {1}", stream.CanRead, stream.CanWrite);
Console.WriteLine("Can timeout: {0}", stream.CanTimeout);
}
static void DisplayCertificateInformation(SslStream stream)
{
Console.WriteLine("Certificate revocation list checked: {0}", stream.CheckCertRevocationStatus);
X509Certificate localCertificate = stream.LocalCertificate;
if (stream.LocalCertificate != null)
{
Console.WriteLine("Local cert was issued to {0} and is valid from {1} until {2}.",
localCertificate.Subject,
localCertificate.GetEffectiveDateString(),
localCertificate.GetExpirationDateString());
}
else
{
Console.WriteLine("Local certificate is null.");
}
// Display the properties of the client's certificate.
X509Certificate remoteCertificate = stream.RemoteCertificate;
if (remoteCertificate != null)
{
Console.WriteLine("Remote cert was issued to {0} and is valid from {1} until {2}.",
remoteCertificate.Subject,
remoteCertificate.GetEffectiveDateString(),
remoteCertificate.GetExpirationDateString());
Console.WriteLine(remoteCertificate);
}
else
{
Console.WriteLine("Remote certificate is null.");
}
}
}
}
My Server
using System;
using System.Configuration;
using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;
using System.Text;
namespace MutualSslDemo.Server
{
class Program
{
static void Main(string[] args)
{
// port
var port = Convert.ToInt32(ConfigurationManager.AppSettings["port"]);
if (port <= 0)
throw new ArgumentException("Please specify a valid port number.");
// certificate and password
var fileName = ConfigurationManager.AppSettings["certificate"];
var password = ConfigurationManager.AppSettings["password"];
var certificate = new X509Certificate2(fileName, password);
ServicePointManager.ServerCertificateValidationCallback += new RemoteCertificateValidationCallback(OnRemoteCertificateValidationCallback);
SslTcpServer.RunServer(port, certificate);
}
static bool OnRemoteCertificateValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
{
return (sslPolicyErrors == SslPolicyErrors.None);
}
public sealed class SslTcpServer
{
// The certificate parameter specifies the name of the file
// containing the machine certificate.
public static void RunServer(int serverPort, X509Certificate2 certificate)
{
// Create a TCP/IP (IPv4) socket and listen for incoming connections.
var listener = new TcpListener(IPAddress.Any, serverPort);
listener.Start();
while (true)
{
Console.WriteLine("Waiting for a client to connect...");
// Application blocks while waiting for an incoming connection.
// Type CNTL-C to terminate the server.
var client = listener.AcceptTcpClient();
ProcessClient(client, certificate);
}
}
static void ProcessClient(TcpClient client, X509Certificate certificate)
{
// A client has connected. Create the
// SslStream using the client's network stream.
var sslStream = new SslStream(client.GetStream(), false);
try
{
// Authenticate the server and requires the client to authenticate.
sslStream.AuthenticateAsServer(certificate, true, SslProtocols.Default, true);
// Display the properties and settings for the authenticated stream.
DisplaySecurityLevel(sslStream);
DisplaySecurityServices(sslStream);
DisplayCertificateInformation(sslStream);
DisplayStreamProperties(sslStream);
// Set timeouts for the read and write to 5 seconds.
sslStream.ReadTimeout = 5000;
sslStream.WriteTimeout = 5000;
// Read a message from the client.
Console.WriteLine("Waiting for client message...");
string messageData = ReadMessage(sslStream);
Console.ForegroundColor = ConsoleColor.Yellow;
Console.WriteLine("Received: {0}", messageData);
Console.ResetColor();
// Write a message to the client.
byte[] message = Encoding.UTF8.GetBytes("Hello from the server.<EOF>");
Console.WriteLine("Sending hello message.");
sslStream.Write(message);
}
catch (AuthenticationException e)
{
Console.WriteLine("Exception: {0}", e.Message);
if (e.InnerException != null)
{
Console.WriteLine("Inner exception: {0}", e.InnerException.Message);
}
Console.WriteLine("Authentication failed - closing the connection.");
sslStream.Close();
client.Close();
return;
}
finally
{
// The client stream will be closed with the sslStream
// because we specified this behavior when creating
// the sslStream.
sslStream.Close();
client.Close();
}
}
static string ReadMessage(SslStream sslStream)
{
// Read the message sent by the client.
// The client signals the end of the message using the
// "<EOF>" marker.
byte[] buffer = new byte[2048];
StringBuilder messageData = new StringBuilder();
int bytes = -1;
do
{
// Read the client's test message.
bytes = sslStream.Read(buffer, 0, buffer.Length);
// Use Decoder class to convert from bytes to UTF8
// in case a character spans two buffers.
Decoder decoder = Encoding.UTF8.GetDecoder();
char[] chars = new char[decoder.GetCharCount(buffer, 0, bytes)];
decoder.GetChars(buffer, 0, bytes, chars, 0);
messageData.Append(chars);
// Check for EOF or an empty message.
if (messageData.ToString().IndexOf("<EOF>") != -1)
{
break;
}
} while (bytes != 0);
return messageData.ToString();
}
static void DisplaySecurityLevel(SslStream stream)
{
Console.WriteLine("Cipher: {0} strength {1}", stream.CipherAlgorithm, stream.CipherStrength);
Console.WriteLine("Hash: {0} strength {1}", stream.HashAlgorithm, stream.HashStrength);
Console.WriteLine("Key exchange: {0} strength {1}", stream.KeyExchangeAlgorithm, stream.KeyExchangeStrength);
Console.WriteLine("Protocol: {0}", stream.SslProtocol);
}
static void DisplaySecurityServices(SslStream stream)
{
Console.WriteLine("Is authenticated: {0} as server? {1}", stream.IsAuthenticated, stream.IsServer);
Console.WriteLine("IsSigned: {0}", stream.IsSigned);
Console.WriteLine("Is Encrypted: {0}", stream.IsEncrypted);
}
static void DisplayStreamProperties(SslStream stream)
{
Console.WriteLine("Can read: {0}, write {1}", stream.CanRead, stream.CanWrite);
Console.WriteLine("Can timeout: {0}", stream.CanTimeout);
}
static void DisplayCertificateInformation(SslStream stream)
{
Console.WriteLine("Certificate revocation list checked: {0}", stream.CheckCertRevocationStatus);
X509Certificate localCertificate = stream.LocalCertificate;
if (stream.LocalCertificate != null)
{
Console.WriteLine("Local cert was issued to {0} and is valid from {1} until {2}.",
localCertificate.Subject,
localCertificate.GetEffectiveDateString(),
localCertificate.GetExpirationDateString());
}
else
{
Console.WriteLine("Local certificate is null.");
}
// Display the properties of the client's certificate.
X509Certificate remoteCertificate = stream.RemoteCertificate;
if (remoteCertificate != null)
{
Console.WriteLine("Remote cert was issued to {0} and is valid from {1} until {2}.",
remoteCertificate.Subject,
remoteCertificate.GetEffectiveDateString(),
remoteCertificate.GetExpirationDateString());
}
else
{
Console.WriteLine("Remote certificate is null.");
}
}
}
}
}
Now, this work if I run both server and client in locally(localhost). However, when I tried this in two different machine (within a network LAN). It throws an error of
Exception: The remote certificate is invalid according to the validation procedure.
in My Server code in this line.
sslStream.AuthenticateAsServer(certificate, true, SslProtocols.Default, true);
In My Client I noticed that the CertificateValidationCallback return true
But I found Local certificate is null in DisplayCertificateInformation
Sorry, I am really new to both C# and security. Can anyone please help me on this. Thanks in advance.