Java

Add a Detached Signature with a Separate Private Key

Demonstrates the Chilkat Mime.AddDetachedSignaturePk method, which creates a detached signature using a signer certificate and its separately supplied private key. The first argument is the Cert and the second is the PrivateKey.

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: Sometimes the certificate and its private key live apart — a .cer alongside a PEM key file, for instance — rather than bundled in a single PFX. This method pairs them explicitly for signing, whereas AddDetachedSignature expects a Cert that already provides its key. The result is the same multipart/signed message.

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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;

    CkMime mime = new CkMime();
    success = mime.SetBodyFromPlainText("This message will be signed.");
    if (success == false) {
        System.out.println(mime.lastErrorText());
        return;
        }

    //  Load the certificate and its private key separately.
    CkCert cert = new CkCert();
    success = cert.LoadFromFile("qa_data/signer.cer");
    if (success == false) {
        System.out.println(cert.lastErrorText());
        return;
        }

    CkPrivateKey privKey = new CkPrivateKey();
    success = privKey.LoadPemFile("qa_data/signer_privkey.pem");
    if (success == false) {
        System.out.println(privKey.lastErrorText());
        return;
        }

    //  Create a detached signature when the certificate and private key are supplied separately.  The
    //  1st argument is the signer certificate and the 2nd is its private key.
    success = mime.AddDetachedSignaturePk(cert,privKey);
    if (success == false) {
        System.out.println(mime.lastErrorText());
        return;
        }

    success = mime.SaveMime("qa_output/signed.eml");
    if (success == false) {
        System.out.println(mime.lastErrorText());
        return;
        }

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