(PHP Extension) RSA Signature/Verify with .key and .cer

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature.

Chilkat PHP Downloads PHP Extension for Windows, Linux, MAC OS X, Alpine Linux, Solaris, OpenBSD, FreeBSD, and Linux armhf/aarch64

<?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.

$privKey = new CkPrivateKey();

// Load the private key from an RSA .key file:
$success = $privKey->LoadPemFile('privateKey.key');
if ($success != true) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

// Get the private key in XML format:
$privKeyXml = $privKey->getXml();

$rsa = new CkRsa();

// Import the private key into the RSA component:
$success = $rsa->ImportPrivateKey($privKeyXml);
if ($success != true) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

// Create the signature as a hex string:
$rsa->put_EncodingMode('hex');

// If some other non-Chilkat application or web service is going to be verifying
// the signature, it is important to match the byte-ordering.
// The LittleEndian property may be set to true
// for little-endian byte ordering, 
// or false  for big-endian byte ordering.
// Microsoft apps typically use little-endian, while
// OpenSSL and other services (such as Amazon CloudFront)
// use big-endian.
$rsa->put_LittleEndian(false);

$strData = 'This is the string to be signed.';

// Sign the string using the sha-1 hash algorithm.
// Other valid choices are "md2", "sha256", "sha384",
// "sha512", and "md5".
$hexSig = $rsa->signStringENC($strData,'sha-1');

print $hexSig . "\n";

// Load a digital certificate from a .cer file:
$cert = new CkCert();

$success = $cert->LoadFromFile('myCert.cer');
if ($success != true) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// pubKey is a CkPublicKey
$pubKey = $cert->ExportPublicKey();

// Now verify using a separate instance of the RSA object:
$rsa2 = new CkRsa();

// Import the public key into the RSA object:
$success = $rsa2->ImportPublicKey($pubKey->getXml());
if ($success != true) {
    print $rsa2->lastErrorText() . "\n";
    exit;
}

// The signature is a hex string, so make sure the EncodingMode is correct:
$rsa2->put_EncodingMode('hex');

// Verify the signature:
$success = $rsa2->VerifyStringENC($strData,'sha-1',$hexSig);
if ($success != true) {
    print $rsa2->lastErrorText() . "\n";
    exit;
}

print 'Success.' . "\n";

?>