(PHP Extension) Verify Opaque Signature and Retrieve Signing Certificates

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign.

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux, Solaris

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

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

$crypt = new CkCrypt2();

// Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
$success = $crypt->VerifyP7M('qa_data/p7m/opaqueSig.p7','qa_output/originalData.dat');
if ($success != true) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

// Alternatively, we can do it in memory...
$binData = new CkBinData();
$success = $binData->LoadFile('qa_data/p7m/opaqueSig.p7');
// Your app should check for success, but we'll skip the check for brevity..

// If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
$success = $crypt->OpaqueVerifyBd($binData);
if ($success != true) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

// For our testing, we signed some text, so we can get it from the binData..
print 'Original Data:' . "\n";
print $binData->getString('utf-8') . "\n";

// After any method call that verifies a signature, the crypt object will contain the certificate(s)
// that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

// Get the number of signing certificates, and get each..
$numCerts = $crypt->get_NumSignerCerts();
$i = 0;
while ($i < $numCerts) {
    // cert is a CkCert
    $cert = $crypt->GetSignerCert($i);
    print $cert->subjectDN() . "\n";

    $i = $i + 1;
}

// We could also get the complete certificate chain of each signer cert,
// assuming the certs in the chain of authentication to the trusted root
// are available on the system, or provided to Chilkat by some other means
// (such as via the XmlCertVault class, the TrustedRoots class, etc.)
$i = 0;
while ($i < $numCerts) {
    // certChain is a CkCertChain
    $certChain = $crypt->GetSignerCertChain($i);
    // You can examine the various properties and methods for certChain in the online
    // reference documentation...

    $i = $i + 1;
}


?>