PHP

A3/A4 Certificate to Create and Verify an Opaque PKCS7/CMS Signature

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Demonstrates how to use an A3 or A4 certificate w/ private key on a smartcard or token 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.

Chilkat2 PHP

<?php

use Chilkat2\Cert;
use Chilkat2\Crypt2;

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

$crypt = new Crypt2();

// 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 smartcards and hardware tokens, PFX/.p12, Java keystore, JWK, Windows registry-based certificate stores, and other sources.
// This example will load the default certificate from the smartcard that is currently in
// the smartcard reader.

$cert = new Cert();

// If the smartcard or token requires a PIN, we can set it here to avoid the dialog...
$cert->SmartCardPin = '000000';

try {
    $cert->LoadFromSmartcard('');

    // Tell it to use the cert and private key we've loaded.
    $crypt->SetSigningCert($cert);

    // Indicate we want the opaque signature in base64 format:
    $crypt->EncodingMode = 'base64';

    // Sign the string using the "utf-8" byte representation:
    $crypt->Charset = 'utf-8';

    // Create the opaque signature:
    $originalData = 'This is the string to be signed.';
    $opaqueSig = $crypt->OpaqueSignStringENC($originalData);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo $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 Crypt2();

// We only need the certificate to verify a signature (and extract the data from
// an opaque signature).  The public key is always embedded within a certificate.
try {
    $vCrypt->SetVerifyCert($cert);

    $vCrypt->EncodingMode = 'base64';
    $vCrypt->Charset = 'utf-8';

    $extractedData = $vCrypt->OpaqueVerifyStringENC($opaqueSig);
} catch (\Chilkat2\Exception $e) {
    echo $e->getMessage(), "\n";
    exit;
}

echo 'The extracted data: ', $extractedData, "\n";

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