(PHP Extension) Sign JSON (or any Text) to Create a Detached PKCS7 Signature

Demonstrates how to sign JSON or any string using a certificate + private key from a .p12/.pfx to create a detached PKCS7 signature. (A detached signature is one that does not embed the original signed data.)

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();

$cert = new CkCert();
$success = $cert->LoadPfxFile('qa_data/pfx/cert_test123.pfx','test123');
if ($success != true) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// Tell the crypt component to use this cert.
$success = $crypt->SetSigningCert($cert);
if ($success != true) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

$crypt->put_HashAlgorithm('sha256');

// By default, all the certs in the chain of authentication are included in the signature.
// If desired, we can choose to only include the signing certificate:
$crypt->put_IncludeCertChain(false);

// Create the detached signature, which does NOT contain the original data.
// To create a PKCS7 signature that contains the original data, see CAdES Sign JSON
$crypt->put_Charset('utf-8');
$detachedSig = new CkByteData();
$stringToSign = '{ \'abc\': 123}';
$success = $crypt->SignString($stringToSign,$detachedSig);
if ($crypt->get_LastMethodSuccess() == false) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

// Verify the signature against the original data.
$verified = $crypt->VerifyString($stringToSign,$detachedSig);
if ($verified == false) {
    print $crypt->lastErrorText() . "\n";
    exit;
}

print 'Success!' . "\n";

?>