(Java) IMAP Download and Verify Signed (S/MIME) Email

Demonstrates how to download and verify digitally signed S/MIME email.

Note: This example requires Chilkat v11.0.0 or greater.

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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;

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

    CkImap imap = new CkImap();

    // Connect to an IMAP server.
    // Use TLS
    imap.put_Ssl(true);
    imap.put_Port(993);
    success = imap.Connect("imap.example.com");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    success = imap.Login("myLogin","myPassword");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Select an IMAP mailbox
    success = imap.SelectMailbox("Inbox");
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // We can choose to fetch UIDs or sequence numbers.
    boolean fetchUids = true;

    // Get the message IDs of all the emails in the mailbox
    CkMessageSet messageSet = new CkMessageSet();
    success = imap.QueryMbx("ALL",fetchUids,messageSet);
    if (success == false) {
        System.out.println(imap.lastErrorText());
        return;
        }

    CkEmail email = new CkEmail();
    CkCert cert = new CkCert();

    int i = 0;
    while (i < messageSet.get_Count()) {

        String uid = messageSet.GetId(i);
        System.out.println("uid: " + uid);

        success = imap.FetchEmail(false,uid,true,email);
        if (success == false) {
            System.out.println(imap.lastErrorText());
            return;
            }

        // The security layers of signed and/or encrypted emails
        // are automatically "unwrapped" when loaded into
        // a Chilkat email object.
        // An application only needs to check to see if an email
        // was received signed or encrypted, and then examine
        // the success/failure.  For example:
        if (email.get_ReceivedSigned() == true) {

            System.out.println("This email was signed.");

            // Check to see if the signatures were verified.
            if (email.get_SignaturesValid() == true) {
                System.out.println("Digital signature(s) verified.");
                System.out.println("Signer: " + email.signedBy());

                // Get the certificate used for signing.
                success = email.LastSignerCert(0,cert);

                if (success == false) {
                    System.out.println("Failed to get signing certificate object.");
                    }
                else {
                    System.out.println("Signing cert: " + cert.subjectCN());
                    }

                }
            else {
                System.out.println("Digital signature verification failed.");
                }

            }

        i = i+1;
        }

    // Disconnect from the IMAP server.
    success = imap.Disconnect();
  }
}