PHP

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. Chilkat2 PHP

<?php

use Chilkat2\Cert;
use Chilkat2\Crypt2;
use Chilkat2\PrivateKey;

// 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 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 Cert();
// The LoadFromFile method will automatically detect the format and load it.
try {
    $cert->LoadFromFile('qa_data/certs/test_12345678a.cer');

    // 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 PrivateKey();
    $password = '12345678a';
    $privKey->LoadPkcs8EncryptedFile('qa_data/certs/test_12345678a.key', $password);

    // Set properties required for signing.

    // Tell it to use the cert and private key we've loaded.
    $crypt->SetSigningCert2($cert, $privKey);

    // 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();

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

try {
    $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.