Java

Add a Detached Signature (Header Placement Control)

Demonstrates the Chilkat Mime.AddDetachedSignature2 method, which creates the same multipart/signed structure as AddDetachedSignature, with a second argument controlling whether the existing message header fields are transferred to the new outer entity.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: Signing wraps the content in a new outer multipart/signed, which raises the question of where the message-level headers (Subject, From, To) should live. This variant lets you choose: transfer them up to the outer entity so the signed message looks like a normal email, or leave them on the inner part. Transferring is typical for email; the finer control matters when the signed entity is embedded in a larger structure.

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

public class ChilkatExample {

    public static void main(String[] args) {
        Mime mime = new Mime();
        try {
            mime.setBodyFromPlainText("This message will be signed.");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Load the signing certificate (which must have access to its private key) from a PFX file.
        // The PFX password should come from a secure source rather than being hard-coded.
        String pfxPassword = "myPfxPassword";
        Cert cert = new Cert();
        try {
            cert.loadPfxFile("qa_data/signer.pfx", pfxPassword);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // AddDetachedSignature2 is the same as AddDetachedSignature, but the 2nd argument controls whether
        // the existing message header fields are transferred to the new outer multipart/signed entity.
        boolean transferHeaderFields = true;
        try {
            mime.addDetachedSignature2(cert, transferHeaderFields);

            mime.saveMime("qa_output/signed.eml");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("Detached signature added (headers transferred).");
    }
}