Verify FTP SSL Server Certificate

This example demonstrates how to verify the FTP server's certificate and authenticity. The intent is to verify the authenticity of the server before passing a login/password to it.

Download Chilkat Java Library

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[])
  {
    CkFtp2 ftp = new CkFtp2();

    boolean success;

    //  Any string unlocks the component for the 1st 30-days.
    success = ftp.UnlockComponent("Anything for 30-day trial");
    if (success != true) {
        System.out.println(ftp.lastErrorText());
        return;
    }

    ftp.put_Hostname("ftp.myftpserver.com");
    ftp.put_Username("myUsername");
    ftp.put_Password("myPassword");

    //  Establish an AUTH SSL secure channel after connection
    //  on the standard FTP port 21.
    ftp.put_AuthSsl(true);

    //  The Ssl property is for establishing an implicit SSL connection
    //  on port 990.  Do not set it.
    ftp.put_Ssl(false);

    //  Indicate that the FTP server must have a verifiable SSL certificate.
    //  Do not accept self-signed certs or certificates that are
    //  expired, revoked, or cannot be verified to a root authority:
    ftp.put_RequireSslCertVerify(true);

    //  You may also set a requirement.  In this example,
    //  the certificate's Common Name (CN) must match the
    //  required string exactly:
    ftp.SetSslCertRequirement("subjectcn","Chilkat Software, Inc.");

    //  Connect and login to the FTP server.
    success = ftp.Connect();
    if (success != true) {
        System.out.println(ftp.lastErrorText());
        return;
    }
    else {
        //  LastErrorText contains information even when
        //  successful. This allows you to visually verify
        //  that the secure connection actually occurred.
        System.out.println(ftp.lastErrorText());
    }

    //  After logging on, you may examine the FTP server's cert:
    CkCert cert;
    cert = ftp.GetSslServerCert();
    if (cert == null ) {
        System.out.println("No server certificate!");
    }
    else {
        //  Display the distinguished name of the SSL cert.
        System.out.println(cert.subjectDN());
    }

    System.out.println("Secure FTP Channel Established!");

    //  Do whatever you're doing to do ...
    //  upload files, download files, etc...

    ftp.Disconnect();
  }
}