(Perl) 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.

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

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

$pdf = chilkat::CkPdf->new();

# 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 == 0) {
    print $pdf->lastErrorText() . "\r\n";
    exit;
}

# Options for signing are specified in JSON.
$json = chilkat::CkJsonObject->new();

# 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

$jpgData = chilkat::CkBinData->new();
$success = $jpgData->LoadFile("qa_data/jpg/university.jpg");
if ($success == 0) {
    print "Failed to load the JPG image." . "\r\n";
    exit;
}

$success = $pdf->SetSignatureJpeg($jpgData);
if ($success == 0) {
    print $pdf->lastErrorText() . "\r\n";
    exit;
}

# 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 = chilkat::CkCert->new();
$success = $cert->LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret");
if ($success == 0) {
    print $cert->lastErrorText() . "\r\n";
    exit;
}

# Tell the pdf object to use the certificate for signing.
$success = $pdf->SetSigningCert($cert);
if ($success == 0) {
    print $pdf->lastErrorText() . "\r\n";
    exit;
}

$success = $pdf->SignPdf($json,"qa_output/hello_signed.pdf");
if ($success == 0) {
    print $pdf->lastErrorText() . "\r\n";
    exit;
}

print "The PDF has been successfully cryptographically signed." . "\r\n";

# 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.