(Java) POP3 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.

    CkMailMan mailman = new CkMailMan();

    // Set the POP3 server's hostname
    mailman.put_MailHost("pop.example.com");

    // Set the POP3 login/password.
    mailman.put_PopUsername("myLogin");
    mailman.put_PopPassword("myPassword");

    CkStringTable stUidls = new CkStringTable();
    success = mailman.FetchUidls(stUidls);
    if (success == false) {
        System.out.println(mailman.lastErrorText());
        return;
        }

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

    int count = stUidls.get_Count();
    int i = 0;
    while (i < count) {
        // Download the full email.
        success = mailman.FetchByUidl(stUidls.stringAt(i),false,0,email);
        if (success == false) {
            System.out.println(mailman.lastErrorText());
            return;
            }

        System.out.println(i);
        System.out.println("From: " + email.ck_from());
        System.out.println("Subject: " + email.subject());

        // 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());

                success = email.LastSignerCert(0,cert);
                if (success == false) {
                    System.out.println(email.lastErrorText());
                    return;
                    }

                System.out.println("Signing cert: " + cert.subjectCN());
                }

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

        i = i+1;
        }

    mailman.Pop3EndSession();
  }
}