Java

Send an Email with a Digital Signature

Demonstrates the Chilkat Email.SendSigned property. Set it to true to have the email sent with a digital signature (the default is false). Signing also requires a certificate with access to its private key. This example loads that certificate (and its private key) from a PFX file with Cert.LoadPfxFile, supplies it via SetSigningCert, and enables signed sending.

Background: Signing is the mirror image of encrypting. To encrypt for a recipient you use their public certificate; to sign you use your own private key, and recipients verify with your public certificate. A signature does not hide the message — a signed email is still readable by anyone — but it proves who sent it and guarantees the content was not tampered with. A PFX (also called PKCS#12, .pfx or .p12) is a password-protected file that bundles a certificate together with its private key, making it a convenient single-file source for signing credentials.

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import com.chilkatsoft.chilkat2.Cert;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Email;

public class ChilkatExample {

    public static void main(String[] args) {
        // Demonstrates the Email.SendSigned property with a full signing setup.  Set SendSigned
        // to true to have the email sent with a digital signature.  Signing requires a certificate
        // with access to its private key, which we load here from a PFX (.pfx / .p12) file.

        Email email = new Email();
        email.setSubject("Signed email");
        email.setBody("This message will be sent with a digital signature.");
        email.setFrom("alice@example.com");
        email.addTo("Bob", "bob@example.com");

        // Load the signing certificate (including its private key) from a PFX file.
        // The 2nd argument is the PFX password.
        Cert cert = new Cert();
        try {
            cert.loadPfxFile("qa_data/certs/signer.pfx", "pfx_password");

            // Provide the signing certificate.
            email.setSigningCert(cert);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Request that the email be sent with a digital signature.
        email.setSendSigned(true);

        System.out.println("SendSigned = " + email.getSendSigned());

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