Java

PDF Signature with Background Image (Seal/Stamp/etc.)

See more PDF Signatures Examples

Demonstrates how to sign a PDF with an appearance that includes a background image, such as a seal, stamp, etc.

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

Chilkat2 Java

import com.chilkatsoft.chilkat2.BinData;
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.
        // The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
        try {
            pdf.loadFile("qa_data/pdf/hello.pdf");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // 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);

        // Put the signature on page 1, top left
        json.updateInt("page", 1);
        json.updateString("appearance.y", "top");
        json.updateString("appearance.x", "left");

        // Use a font scale of 10.0
        json.updateString("appearance.fontScale", "10.0");

        // In this example, the appearance of the digital signature will contain three lines:
        // 1) The signing certificate's common name
        // 2) The current date/time
        // 3) Some arbitrary text.
        // The keyword "cert_cn" is replaced with the Certificate's Subject Common Name.
        // The keyword "current_dt" is replaced with the current date/time.
        // Any number of appearance text lines can be added.
        json.updateString("appearance.text[0]", "Digitally signed by: cert_cn");
        json.updateString("appearance.text[1]", "current_dt");
        json.updateString("appearance.text[2]", "The crazy brown fox jumps over the lazy dog.");

        // Load a JPG image to be shown with 30% opacity in the background.
        // (the image must be in the JPG format)
        // The sample university.jpb is available at https://example-code.com/images/university.jpg

        BinData jpgData = new BinData();
        try {
            jpgData.loadFile("qa_data/jpg/university.jpg");
        } catch (ChilkatException e) {
            System.out.println("Failed to load the JPG image.");
            return;
        }

        try {
            pdf.setSignatureJpeg(jpgData);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Specify that we want to display the JPG image in the center with 30% opacity.
        json.updateString("appearance.image", "custom-jpg");
        json.updateString("appearance.imagePlacement", "center");
        json.updateString("appearance.imageOpacity", "30");

        // 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);

            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.");

        // The appearance of the signature appears in Adobe Acrobat as shown below.
        // The JPG is automatically scaled to the size of the signature based on the signature's font scale
        // and number of text lines.
        // 
    }
}