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.

Chilkat Java Downloads

Download Chilkat for Java

Java

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;

    //  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.

    CkEmail email = new CkEmail();

    success = email.LoadEml("qa_data/eml/signed.eml");
    if (success == false) {
        System.out.println(email.lastErrorText());
        return;
        }

    if (email.get_ReceivedSigned() == true) {
        System.out.println("This email was received with a digital signature.");
        if (email.get_SignaturesValid() == true) {
            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.
  }
}