Java

Check if an Email Was Received Digitally Signed

Demonstrates the read-only Chilkat Email.ReceivedSigned property, which is true if the email was originally received carrying one or more digital signatures. Knowing a message was signed is separate from knowing the signature checked out, so this example also reads SignaturesValid to report whether the signed content verified.

Background: A digital signature on an email (S/MIME) provides two things: authenticity (it was really sent by the holder of a particular certificate) and integrity (the content was not altered in transit). The sender signs a hash of the message with their private key; the recipient verifies it with the sender's public certificate. ReceivedSigned simply tells you a signature is present — verifying it is a separate step exposed through SignaturesValid.

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Chilkat2 Java

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

public class ChilkatExample {

    public static void main(String[] args) {
        // Demonstrates the read-only Email.ReceivedSigned property, which is true if this
        // email was originally received with a digital signature.  Use SignaturesValid to
        // determine whether the signed content actually verified.

        Email email = new Email();

        try {
            email.loadEml("qa_data/eml/signed.eml");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        if (email.getReceivedSigned()) {
            System.out.println("This email was received with a digital signature.");
            if (email.getSignaturesValid()) {
                System.out.println("All signatures are valid.");
            } else {
                System.out.println("One or more signatures are NOT valid.");
            }
        } else {
            System.out.println("This email was not signed.");
        }

        // Note: Paths such as "qa_data/..." are relative local filesystem paths,
        // relative to the current working directory of the running application.
    }
}