PHP Extension 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. 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.

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

//  The signing certificate, with its private key.
$cert = new CkCert();
$success = $cert->LoadPfxFile('qa_data/pfx/myPdfSigningCert.pfx','secret');
if ($success == false) {
    print $cert->lastErrorText() . "\n";
    exit;
}

$pdf = new CkPdf();
$success = $pdf->LoadFile('qa_data/pdf/two_page_memo.pdf');
if ($success == false) {
    print $pdf->lastErrorText() . "\n";
    exit;
}

//  Encrypt with AES-256 and do not permit modifying.
$pdf->put_UserPassword('user-secret');
$pdf->put_OwnerPassword('owner-secret');
$json = new CkJsonObject();
$json->UpdateBool('permissions.modify',false);
$jsonOut = new CkJsonObject();
$success = $pdf->Protection('encrypt',$json,$jsonOut);
if ($success == false) {
    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 == false) {
    print $pdf->lastErrorText() . "\n";
    exit;
}

$sigOpts = new CkJsonObject();
$sigOpts->UpdateBool('invisibleSignature',true);
$sigOpts->UpdateInt('signingCertificateV2',1);
$sigOpts->UpdateInt('signingTime',1);
$success = $pdf->SignPdf($sigOpts,'qa_output/memo_encrypted_signed.pdf');
if ($success == false) {
    print $pdf->lastErrorText() . "\n";
    exit;
}

//  The result is encrypted and signed.
$check = new CkPdf();
$check->put_UserPassword('user-secret');
$success = $check->LoadFile('qa_output/memo_encrypted_signed.pdf');
if ($success == false) {
    print $check->lastErrorText() . "\n";
    exit;
}

$empty = new CkJsonObject();
$info = new CkJsonObject();
$success = $check->Protection('getInfo',$empty,$info);
if ($success == false) {
    print $check->lastErrorText() . "\n";
    exit;
}

print 'algorithm: ' . $info->stringOf('loaded.algorithm') . "\n";
print 'signatures: ' . $check->get_NumSignatures() . "\n";
$sigInfo = new CkJsonObject();
$verified = $check->VerifySignature(0,$sigInfo);
print 'signature verifies: ' . $verified . "\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 == false) {
    print $check->lastErrorText() . "\n";
    exit;
}

$success = $check->SignPdf($sigOpts,'qa_output/memo_signed_twice.pdf');
if ($success == false) {
    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.
$owner = new CkPdf();
$owner->put_UserPassword('user-secret');
$owner->put_OwnerPassword('owner-secret');
$success = $owner->LoadFile('qa_output/memo_encrypted_signed.pdf');
if ($success == false) {
    print $owner->lastErrorText() . "\n";
    exit;
}

$success = $owner->SetSigningCert($cert);
if ($success == false) {
    print $owner->lastErrorText() . "\n";
    exit;
}

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

$twice = new CkPdf();
$twice->put_UserPassword('user-secret');
$success = $twice->LoadFile('qa_output/memo_signed_twice.pdf');
if ($success == false) {
    print $twice->lastErrorText() . "\n";
    exit;
}

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

?>