PHP Extension

Sign PDF with Invisible Signature

See more PDF Signatures Examples

Demonstrates how to sign a PDF with an invisible signature.

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

PHP Extension

<?php

include("chilkat.php");

$success = false;

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

$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) {
    print $pdf->lastErrorText() . "\n";
    exit;
}

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

// In most cases, the signingCertificateV2 and signingTime attributes are required.
$json->UpdateInt('signingCertificateV2',1);
$json->UpdateInt('signingTime',1);

// Indicate that the signature will be invisible.
$json->UpdateBool('invisibleSignature',true);

// Load the signing certificate. (Use your own certificate.)
$cert = new CkCert();
$success = $cert->LoadPfxFile('qa_data/pfx/myPdfSigningCert.pfx','secret');
if ($success == false) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// Tell the pdf object to use the certificate for signing.
$success = $pdf->SetSigningCert($cert);
if ($success == false) {
    print $pdf->lastErrorText() . "\n";
    exit;
}

$success = $pdf->SignPdf($json,'qa_output/hello_signed.pdf');
if ($success == false) {
    print $pdf->lastErrorText() . "\n";
    exit;
}

print 'PDF successfully signed with an invisible signature.' . "\n";

// An invisible signature has no appearance within the PDF document itself,
// but Adobe Acrobat will indicate the document is signed in a toolbar, as shown here:
// (image:https://example-code.com/images/invisible_signature.jpg/endImage)

?>