(Node.js) 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.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var pdf = new chilkat.Pdf();

    // Load a PDF to be signed.
    // The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
    var success = pdf.LoadFile("qa_data/pdf/hello.pdf");
    if (success == false) {
        console.log(pdf.LastErrorText);
        return;
    }

    // Options for signing are specified in JSON.
    var json = new chilkat.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

    var jpgData = new chilkat.BinData();
    success = jpgData.LoadFile("qa_data/jpg/university.jpg");
    if (success == false) {
        console.log("Failed to load the JPG image.");
        return;
    }

    success = pdf.SetSignatureJpeg(jpgData);
    if (success == false) {
        console.log(pdf.LastErrorText);
        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.)
    var cert = new chilkat.Cert();
    success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret");
    if (success == false) {
        console.log(cert.LastErrorText);
        return;
    }

    // Tell the pdf object to use the certificate for signing.
    success = pdf.SetSigningCert(cert);
    if (success == false) {
        console.log(pdf.LastErrorText);
        return;
    }

    success = pdf.SignPdf(json,"qa_output/hello_signed.pdf");
    if (success == false) {
        console.log(pdf.LastErrorText);
        return;
    }

    console.log("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.
    

}

chilkatExample();