(C#) Examine Client Certificates for an Accepted TLS Connection

Demonstrates how to access the client certificates for a TLS connection accepted by your application acting as the server.

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.Socket listenSslSocket = new Chilkat.Socket();

// An SSL/TLS server needs a digital certificate.  This example loads it from a PFX file.
// This is the server's certificate.

Chilkat.Cert cert = new Chilkat.Cert();
bool success = cert.LoadPfxFile("qa_data/serverCert/myServerCert.pfx","pfx_password");
if (success != true) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// To accept client client certificates in the TLS handshake,
// we must indicate a list of acceptable client certificate root CA DN's
// that are allowed.  (DN is an acronym for Distinguished Name.)
// Call AddSslAcceptableClientCaDn once for each acceptable CA DN.
// Here are a few examples so you can see the general format of a DN.
listenSslSocket.AddSslAcceptableClientCaDn("C=SE, O=AddTrust AB, OU=AddTrust External TTP Network, CN=AddTrust External CA Root");
listenSslSocket.AddSslAcceptableClientCaDn("O=Digital Signature Trust Co., CN=DST Root CA X3");

// Initialize with our server's TLS certificate.
success = listenSslSocket.InitSslServer(cert);
if (success != true) {
    Debug.WriteLine(listenSslSocket.LastErrorText);
    return;
}

// Bind and listen on a port:
int myPort = 8123;
// Allow for a max of 5 queued connect requests.
int backLog = 5;
success = listenSslSocket.BindAndListen(myPort,backLog);
if (success != true) {
    Debug.WriteLine(listenSslSocket.LastErrorText);
    return;
}

// Accept the next incoming connection.
int maxWaitMillisec = 20000;
Chilkat.Socket clientSock = listenSslSocket.AcceptNextConnection(maxWaitMillisec);
if (listenSslSocket.LastMethodSuccess == false) {
    Debug.WriteLine(listenSslSocket.LastErrorText);
    return;
}

// Examine the client certs chain.  The 1st cert will be the client certificate, and
// the subsequent certs will be the certs in the chain of authentication.
int numClientCerts = clientSock.NumReceivedClientCerts;
Debug.WriteLine("numClientCerts = " + Convert.ToString(numClientCerts));

int i = 0;
while (i < numClientCerts) {
    Chilkat.Cert clientCert = clientSock.GetReceivedClientCert(i);
    Debug.WriteLine(clientCert.SubjectDN);

    i = i + 1;
}

// Close the connection with the client
success = clientSock.Close(1000);