Java

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.

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Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean 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 = new CkMailMan();

    //  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 = new CkCert();
    success = cert.LoadPfxFile("qa_data/certs/client.pfx","pfx_password");
    if (success == false) {
        System.out.println(cert.lastErrorText());
        return;
        }

    //  Use this certificate to identify the client during the TLS handshake.
    success = mailman.SetSslClientCert(cert);
    if (success == false) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    success = mailman.VerifySmtpLogin();
    if (success == false) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    System.out.println("Connected using a TLS client certificate.");

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