Java

PDF Sign Under Existing Signature

See more PDF Signatures Examples

This example explains how sign a previously-signed PDF and place the signature appearance below the existing signature.

Note: This example requires Chilkat v9.5.0.85 or greater.

Chilkat2 Java

import com.chilkatsoft.chilkat2.Cert;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.JsonObject;
import com.chilkatsoft.chilkat2.Pdf;

public class ChilkatExample {

    public static void main(String[] args) {
        // This example requires the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        Pdf pdf = new Pdf();

        // Load a PDF to be signed.
        try {
            pdf.loadFile("qa_data/pdf/sign_testing_4/hello_signed.pdf");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // The PDF we'll be signing already has a signature added in Adobe Acrobat DC.
        // It looks like this:
        // (Notice the Adobe background logo, which is commonly what you'll see when a signature
        // is created by Adobe Acrobat.  Chilkat (obviously) does not create signatures using the Adobe
        // logo because it would be a copyright violation.)

        // 

        // Options for signing are specified in JSON.
        JsonObject json = new JsonObject();

        // In most cases, the signingCertificateV2 and signingTime attributes are required.
        json.updateInt("signingCertificateV2", 1);
        json.updateInt("signingTime", 1);

        // To put our new signature underneath the existing signature, we have to specify the page
        // where the existing signature is found, and then we can specify "under" for the "appearance.y"
        json.updateInt("page", 1);
        json.updateString("appearance.y", "under");

        json.updateString("appearance.fontScale", "10.0");

        json.updateString("appearance.text[0]", "Reason: Agreement Accepted by John");
        json.updateString("appearance.text[1]", "Date: current_dt");

        // Load the signing certificate. (Use your own certificate.)
        Cert cert = new Cert();
        try {
            cert.loadPfxFile("qa_data/pfx/myPdfSigningCert.pfx", "secret");

            // Tell the pdf object to use the certificate for signing.
            pdf.setSigningCert(cert);

            // Note: When adding an additional signature to a PDF, the existing signatures
            // are validated, and this includes validating the certificates previously used to
            // create the existing signatures.  (A signature typically embeds the signing certs.)
            // In some cases, the certificates and/or certs in the chain of authentication for
            // existing signatures are not present, and are not available on the current system.
            // In this case, you can skip the validation by setting this keyword in UncommonOptions:
            pdf.setUncommonOptions("NO_VERIFY_CERT_SIGNATURES");

            pdf.signPdf(json, "qa_output/hello_signed.pdf");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("The PDF has been successfully cryptographically signed.");

        // Here's a screenshot of the 2nd signature positioned under the 1st in Adobe Acrobat:

        // 
    }
}