PHP Extension

Create and Verify an Opaque PKCS7/CMS Signature

See more Digital Signatures Examples

Demonstrates how to create a PKCS7 opaque signature, and also how to verify an opaque signature. An opaque signature is different than a detached PKCS7 signature in that it contains the original data. Verifying an opaque signature retrieves the original content. PHP Extension

<?php

include("chilkat.php");

$success = false;

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

$crypt = new CkCrypt2();

// A certificate and private key is needed to create a signature.
// Chilkat provides many different ways to load a certificate and private key, such
// as from a PFX/.p12, Java keystore, JWK, Windows registry-based certificate stores, and other sources.
// This example will load the certificate from a .crt and the private key from a .key file

$cert = new CkCert();
// The LoadFromFile method will automatically detect the format and load it.
$success = $cert->LoadFromFile('qa_data/certs/test_12345678a.cer');
if ($success != true) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// Our private key is in an encrypted PKCS8 format.
// If you don't know the format of your key, but you do know it's encrypted,
// and requires a password, then just call any of the Chilkat methods that load
// a private key w/ a password argument.  Chilkat will auto-detect the format
// and load it correctly even if it's not the format indicated by the method name..
$privKey = new CkPrivateKey();
$password = '12345678a';
$success = $privKey->LoadPkcs8EncryptedFile('qa_data/certs/test_12345678a.key',$password);
if ($success != true) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

// Set properties required for signing.

// Tell it to use the cert and private key we've loaded.
$success = $crypt->SetSigningCert2($cert,$privKey);
if ($success != true) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

// Indicate we want the opaque signature in base64 format:
$crypt->put_EncodingMode('base64');

// Sign the string using the "utf-8" byte representation:
$crypt->put_Charset('utf-8');

// Create the opaque signature:
$originalData = 'This is the string to be signed.';
$opaqueSig = $crypt->opaqueSignStringENC($originalData);
if ($crypt->get_LastMethodSuccess() != true) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

print $opaqueSig . "\n";

// The output looks like this:
// MIIPgQYJKoZIhvcNAQcCoIIPcjCCD24CAQExCzAJBgUrDgMCGgUAMC8GCSqGSIb3DQEHAaAiBCBUaGlzIGlzIHRoZSBzdHJpbmcgdG8gYmUgc...

// ----------------------------------------------------------------------------------------------
// Now let's verify the signature and retrieve the original data.
// We'll use a new Crypt2 object to keep things completely separate...

$vCrypt = new CkCrypt2();

$vCrypt->put_EncodingMode('base64');
$vCrypt->put_Charset('utf-8');

$extractedData = $vCrypt->opaqueVerifyStringENC($opaqueSig);
if ($vCrypt->get_LastMethodSuccess() != true) {
    print $vCrypt->lastErrorText() . "\n";
    exit;
}

print 'The extracted data: ' . $extractedData . "\n";

// The output is:
// The extracted data: This is the string to be signed.

?>