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Asked: 2026-05-28T20:42:37+00:00

I’m working on a server application that needs to communicate with clients through sockets.

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I’m working on a server application that needs to communicate with clients through sockets. In the middle of connection after initial data exchange, clients require a secure connection over sockets.

So I initiate the secure connection like calling StartupSSLHandshake() method;

    private void StartupSSLHandshake()
    {
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls | SecurityProtocolType.Ssl3;

        using (var networkStream = new NetworkStream(this.Connection._Socket, true))
        {
            this.SSLStream = new SslStream(networkStream, false);
            
            try
            {
                this.SSLStream.AuthenticateAsServer(CertificateHelper.Certificate, true, SslProtocols.Tls, true);

                Console.WriteLine("Cipher: {0} strength {1}", SSLStream.CipherAlgorithm, SSLStream.CipherStrength);
                Console.WriteLine("Hash: {0} strength {1}", SSLStream.HashAlgorithm, SSLStream.HashStrength);
                Console.WriteLine("Key exchange: {0} strength {1}", SSLStream.KeyExchangeAlgorithm, SSLStream.KeyExchangeStrength);
                Console.WriteLine("Protocol: {0}", SSLStream.SslProtocol);

            }
            catch(AuthenticationException e)
            {
                Logger.FatalException(e, "Certificate exception");
            }
        }
    }

Further more I generate my server-sertificate at run time using http://blogs.msdn.com/b/dcook/archive/2008/11/25/creating-a-self-signed-certificate-in-c.aspx

And here’s my CertificateHelper class that generates it if needed:

public static class CertificateHelper
{
    public const string SertificateFile = "cert.pfx";
    public static X509Certificate Certificate = null;

    static CertificateHelper()
    {
        if (!CertificateExists())
            Create();

        Certificate = new X509Certificate2(SertificateFile, "mypassword");
    }

    private static void Create()
    {
        byte[] certificate = CertificateCreator.CreateSelfSignCertificatePfx("CN=mydomain.org", DateTime.Parse("2011-01-01"), DateTime.Parse("2013-01-01"), "mypassword");

        using (var writer = new BinaryWriter(File.Open(SertificateFile, FileMode.Create)))
        {
            writer.Write(certificate);
        }
    }

    public static bool CertificateExists()
    {
        return File.Exists(SertificateFile);
    }
}

So when I try to run it against clients (which are probably using OpenSSL libs), no matter what I try, I just get "The client and server cannot communicate, because they do not possess a common algorithm" exception;

[15.11.2011 11:01:06.771] [Fatal] [Server]: Certificate exception - [Exception] System.Security.Authentication.AuthenticationException: A call to SSPI failed, see inner exception. ---> System.ComponentModel.Win32Exception: The client and server cannot communicate, because they do not possess a common algorithm
   --- End of inner exception stack trace ---
   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)
   at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
   at System.Net.Security.SslStream.AuthenticateAsServer(X509Certificate serverCertificate, Boolean clientCertificateRequired, SslProtocols enabledSslProtocols, Boolean checkCertificateRevocation)
   at Server.StartupSSLHandshake() in xyz.cs:line 293

So I enabled socket-tracing and here’s the output;

System.Net Information: 0 : [4828] SecureChannel#60869981::.ctor(hostname=?124, #clientCertificates=0, encryptionPolicy=RequireEncryption)
System.Net Information: 0 : [4828] Enumerating security packages:
System.Net Information: 0 : [4828]     Negotiate
System.Net Information: 0 : [4828]     NegoExtender
System.Net Information: 0 : [4828]     Kerberos
System.Net Information: 0 : [4828]     NTLM
System.Net Information: 0 : [4828]     Schannel
System.Net Information: 0 : [4828]     Microsoft Unified Security Protocol Provider
System.Net Information: 0 : [4828]     WDigest
System.Net Information: 0 : [4828]     TSSSP
System.Net Information: 0 : [4828]     pku2u
System.Net Information: 0 : [4828]     CREDSSP
System.Net.Sockets Verbose: 0 : [4828] Socket#5655257::Receive()
System.Net.Sockets Verbose: 0 : [4828] Data from Socket#5655257::Receive
System.Net.Sockets Verbose: 0 : [4828] 00000000 : 16 03 01 00 3B                                  : ....;
System.Net.Sockets Verbose: 0 : [4828] Exiting Socket#5655257::Receive()    -> 5#5
System.Net.Sockets Verbose: 0 : [4828] Socket#5655257::Receive()
System.Net.Sockets Verbose: 0 : [4828] Data from Socket#5655257::Receive
System.Net.Sockets Verbose: 0 : [4828] 00000005 : 01 00 00 37 03 01 4E C2-2A 52 03 2A 4F BC 0F 94 : ...7..N.*R.*O...
System.Net.Sockets Verbose: 0 : [4828] 00000015 : E2 AE B5 1D 99 1A 21 D3-DF 6C 16 47 71 23 D0 F3 : ......!..l.Gq#..
System.Net.Sockets Verbose: 0 : [4828] 00000025 : AD E9 A9 3F 22 E8 00 00-0A 00 8D 00 8B 00 8C 00 : ...?"...........
System.Net.Sockets Verbose: 0 : [4828] 00000035 : 8A 00 FF 01 00 00 04 00-23 00 00                : ........#..
System.Net.Sockets Verbose: 0 : [4828] Exiting Socket#5655257::Receive()    -> 59#59
System.Net Information: 0 : [4828] SecureChannel#60869981 - Locating the private key for the certificate: [Version]
  V3

[Subject]
  CN=mydomain.org
  Simple Name: mydomain.org
  DNS Name: mydomain.org

[Issuer]
  CN=mydomain.org
  Simple Name: mydomain.org
  DNS Name: mydomain.org

[Serial Number]
  2C7ECC7CAEB576AB48F47A5F356D5B61

[Not Before]
  01.01.2011 00:00:00

[Not After]
  01.01.2013 00:00:00

[Thumbprint]
  5DA4607C89339CB550DF52A2608B9ABFBFFC90EB

[Signature Algorithm]
  sha1RSA(1.2.840.113549.1.1.5)

[Public Key]
  Algorithm: RSA
  Length: 1024
  Key Blob: 30 81 89 02 81 81 00 a9 e8 b1 cc 71 e5 7e 1a c8 ba bc c9 32 bb e3 b3 f3 66 d6 9b bb 3d b8 41 0d ef 45 06 cc f5 49 bf 10 7a 39 28 60 e5 33 93 b1 d1 78 f6 97 fc 28 c5 cc 66 28 db 43 8a 8e 26 39 cb 84 c9 fe 96 a7 83 e8 f7 03 37 6a 91 fe 36 1c bf 66 5e 1e 2e 41 62 3f 41 ab d9 cf ac 4d 4c cd 79 3d ab 97 9d ce 57 ec 60 bb f8 65 d8 ad 5d 24 0a e2 a0 33 9e 7d 01 41 77 7a 0d 0e 13 36 dc ee 16 eb 35 ab 89 2c 11 02 03 01 00 01
  Parameters: 05 00

[Private Key]
  Key Store: User
  Provider Name: Microsoft Enhanced Cryptographic Pro....
System.Net Information: 0 : [4828] SecureChannel#60869981 - Certificate is of type X509Certificate2 and contains the private key.
System.Net Information: 0 : [4828] AcquireCredentialsHandle(package = Microsoft Unified Security Protocol Provider, intent  = Inbound, scc     = System.Net.SecureCredential)
System.Net Information: 0 : [4828] AcceptSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = (null), inFlags = MutualAuth, ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitIntegrity)
System.Net Information: 0 : [4828] AcceptSecurityContext(In-Buffer length=64, Out-Buffer length=0, returned code=AlgorithmMismatch).
System.Net.Sockets Verbose: 0 : [4828] Socket#5655257::Dispose()

It tells me about that AlgorithmMismatch;

System.Net Information: 0 : [4828] AcceptSecurityContext(In-Buffer length=64, Out-Buffer length=0, returned code=AlgorithmMismatch).

Further found that client uses this chippers;

  • Cipher Suite: TLS_PSK_WITH_AES_256_CBC_SHA (0x008d)
  • Cipher Suite: TLS_PSK_WITH_3DES_EDE_CBC_SHA (0x008b)
  • Cipher Suite: TLS_PSK_WITH_AES_128_CBC_SHA (0x008c)
  • Cipher Suite: TLS_PSK_WITH_RC4_128_SHA (0x008a)
  • Cipher Suite: TLS_EMPTY_RENEGOTIATION_INFO_SCSV (0x00ff)

Does SSLStream any support these?

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1 Answer

  1. Editorial Team

    Windows does not support any of the TLS_PSK ciphersuites, so the server has no common algorithm with the client. If you can configure the client to use non-PSK based ciphersuites, you can get things to work.

    PSK stands for “PreShared Key”, so these are all certificates that use a share key (such as password) to establish TLS channel. You don’t need a certificate for such TLS connection, but Windows doesn’t have support for this.

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