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

See more PDF Signatures Examples

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

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

var success = false;

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

var pdf = new CkPdf();

// Load a PDF to be signed.
// The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
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 CkJsonObject();

// 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 CkBinData();
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 CkCert();
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.