Perl Requires Chilkat v11.7.0+

Encrypt and Sign a PDF, and Sign an Encrypted PDF

See more PDF Protection Examples

Demonstrates signing together with encryption. A pending encrypt is applied by SignPdf before it signs, so one call produces a PDF that is both encrypted and signed. A PDF that is already encrypted can be signed too, and stays encrypted. When it was opened with only the user password its permissions decide: adding a signature field needs both the modify and the annotate permission. Loading the PDF with its owner password lifts that. Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

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

# The PDF used in this example is available at two_page_memo.pdf

# The signing certificate, with its private key.
my $cert = Chilkat2::Cert->new;
my $success = $cert->LoadPfxFile('qa_data/pfx/myPdfSigningCert.pfx', 'secret');
if (!$success) {
    print $cert->LastErrorText, "\n";
    exit;
}

my $pdf = Chilkat2::Pdf->new;
$success = $pdf->LoadFile('qa_data/pdf/two_page_memo.pdf');
if (!$success) {
    print $pdf->LastErrorText, "\n";
    exit;
}

# Encrypt with AES-256 and do not permit modifying.
$pdf->UserPassword('user-secret');
$pdf->OwnerPassword('owner-secret');
my $json = Chilkat2::JsonObject->new;
$json->UpdateBool('permissions.modify', 0);
my $jsonOut = Chilkat2::JsonObject->new;
$success = $pdf->Protection('encrypt', $json, $jsonOut);
if (!$success) {
    print $pdf->LastErrorText, "\n";
    exit;
}

# The encryption is still pending.  SignPdf applies it first and signs the encrypted result.
$success = $pdf->SetSigningCert($cert);
if (!$success) {
    print $pdf->LastErrorText, "\n";
    exit;
}

my $sigOpts = Chilkat2::JsonObject->new;
$sigOpts->UpdateBool('invisibleSignature', 1);
$sigOpts->UpdateInt('signingCertificateV2', 1);
$sigOpts->UpdateInt('signingTime', 1);
$success = $pdf->SignPdf($sigOpts, 'qa_output/memo_encrypted_signed.pdf');
if (!$success) {
    print $pdf->LastErrorText, "\n";
    exit;
}

# The result is encrypted and signed.
my $check = Chilkat2::Pdf->new;
$check->UserPassword('user-secret');
$success = $check->LoadFile('qa_output/memo_encrypted_signed.pdf');
if (!$success) {
    print $check->LastErrorText, "\n";
    exit;
}

my $empty = Chilkat2::JsonObject->new;
my $info = Chilkat2::JsonObject->new;
$success = $check->Protection('getInfo', $empty, $info);
if (!$success) {
    print $check->LastErrorText, "\n";
    exit;
}

print 'algorithm: ', $info->StringOf('loaded.algorithm'), "\n";
print 'signatures: ', $check->NumSignatures, "\n";
my $sigInfo = Chilkat2::JsonObject->new;
my $verified = $check->VerifySignature(0, $sigInfo);
print 'signature verifies: ', ($verified ? 1 : 0), "\n";

# Signing an encrypted PDF.  This one was opened with only the user password, and its
# permissions do not allow modifying, so another signature is refused.
$success = $check->SetSigningCert($cert);
if (!$success) {
    print $check->LastErrorText, "\n";
    exit;
}

$success = $check->SignPdf($sigOpts, 'qa_output/memo_signed_twice.pdf');
if (!$success) {
    print "A second signature was refused: the permissions do not allow it.\n";
}

# Loaded with the owner password, the same PDF can be signed.  It stays encrypted, and the
# first signature stays valid because the new one is added as an incremental update.
my $owner = Chilkat2::Pdf->new;
$owner->UserPassword('user-secret');
$owner->OwnerPassword('owner-secret');
$success = $owner->LoadFile('qa_output/memo_encrypted_signed.pdf');
if (!$success) {
    print $owner->LastErrorText, "\n";
    exit;
}

$success = $owner->SetSigningCert($cert);
if (!$success) {
    print $owner->LastErrorText, "\n";
    exit;
}

$success = $owner->SignPdf($sigOpts, 'qa_output/memo_signed_twice.pdf');
if (!$success) {
    print $owner->LastErrorText, "\n";
    exit;
}

my $twice = Chilkat2::Pdf->new;
$twice->UserPassword('user-secret');
$success = $twice->LoadFile('qa_output/memo_signed_twice.pdf');
if (!$success) {
    print $twice->LastErrorText, "\n";
    exit;
}

print 'signatures after signing with owner rights: ', $twice->NumSignatures, "\n";
$verified = $twice->VerifySignature(0, $sigInfo);
print 'first signature still verifies: ', ($verified ? 1 : 0), "\n";
$verified = $twice->VerifySignature(1, $sigInfo);
print 'second signature verifies: ', ($verified ? 1 : 0), "\n";

# Sample output:

# algorithm: aes-256
# signatures: 1
# signature verifies: True
# A second signature was refused: the permissions do not allow it.
# signatures after signing with owner rights: 2
# first signature still verifies: True
# second signature verifies: True