C++

Use a TLS Client Certificate

Demonstrates the Chilkat MailMan.SetSslClientCert method, which sets the client-side certificate to use for SSL/TLS connections. This is typically not required — most SSL/TLS connections authenticate the server only. This example loads a client certificate from a PFX and uses it when connecting.

Background: In an ordinary TLS handshake only the server presents a certificate, and the client proves who it is later with a password. Mutual TLS adds a second leg: the client also presents a certificate, so it is authenticated cryptographically at the transport layer. Some corporate or high-security mail servers require this. Because the client must prove possession of the key, the certificate needs its private key — hence loading from a PFX.

Chilkat C++ Downloads

Download Chilkat for C++

C++

#include <CkMailMan.h>
#include <CkCert.h>

void ChilkatSample(void)
    {
    bool success = false;

    //  Demonstrates the MailMan.SetSslClientCert method, which sets the client-side certificate
    //  to use for SSL/TLS connections.  This is typically not required -- most SSL/TLS
    //  connections authenticate the server only.

    CkMailMan mailman;

    //  Configure the SMTP server connection.
    mailman.put_SmtpHost("smtp.example.com");
    mailman.put_SmtpPort(465);
    mailman.put_SmtpSsl(true);
    mailman.put_SmtpUsername("user@example.com");
    mailman.put_SmtpPassword("myPassword");

    //  Load the client certificate (with its private key) from a PFX file.
    CkCert cert;
    success = cert.LoadPfxFile("qa_data/certs/client.pfx","pfx_password");
    if (success == false) {
        std::cout << cert.lastErrorText() << "\r\n";
        return;
    }

    //  Use this certificate to identify the client during the TLS handshake.
    success = mailman.SetSslClientCert(cert);
    if (success == false) {
        std::cout << mailman.lastErrorText() << "\r\n";
        return;
    }

    success = mailman.VerifySmtpLogin();
    if (success == false) {
        std::cout << mailman.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "Connected using a TLS client certificate." << "\r\n";

    //  Note: The path "qa_data/certs/client.pfx" is a relative local filesystem path,
    //  relative to the current working directory of the running application.
    }