(PHP ActiveX) Get RSA Key Modulus from .cer or .key

Demonstrates how to get the RSA key modulus from either the certificate (.cer) or RSA key (.key). OpenSSL commands to do the same would be:

openssl x509 -inform DER -in "test.cer"  -modulus -noout 

openssl pkcs8 -inform DER -in​ "test.key"​ -outform PEM -passin pass:"12345​678a​"
   | openssl rsa -inform PEM -modulus -noout 

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows Note: The php_com_dotnet.dll may need to be enabled inside of php.ini.

<?php

// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.PrivateKey')
$privKey = new COM("Chilkat.PrivateKey");

$password = '12345678a';
$success = $privKey->LoadPkcs8EncryptedFile('qa_data/certs/test_12345678a.key',$password);
if ($success != 1) {
    print $privKey->LastErrorText . "\n";
    exit;
}

// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.Xml')
$xml = new COM("Chilkat.Xml");
$xml->LoadXml($privKey->getXml());

// The XML contains the parts of the key in base64.
print 'Private Key XML:' . "\n";
print $xml->getXml() . "\n";

// We can get the base64 modulus like this:
$modulus = $xml->getChildContent('Modulus');
print 'base64 modulus = ' . $modulus . "\n";

// To convert to hex:
// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.BinData')
$binDat = new COM("Chilkat.BinData");
$binDat->AppendEncoded($modulus,'base64');
$hexModulus = $binDat->getEncoded('hex');
print 'hex modulus = ' . $hexModulus . "\n";

// Now get the modulus from the cert:
// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.Cert')
$cert = new COM("Chilkat.Cert");

$success = $cert->LoadFromFile('qa_data/certs/test_12345678a.cer');
if ($success != 1) {
    print $cert->LastErrorText . "\n";
    exit;
}

// The cert contains the public key, which is composed of the
// modulus + exponent (for RSA keys).
// pubKey is a Chilkat.PublicKey
$pubKey = $cert->ExportPublicKey();

$xml->LoadXml($pubKey->getXml());
print 'Public Key XML:' . "\n";
print $xml->getXml() . "\n";

// Proceed in the same way as before....
$modulus = $xml->getChildContent('Modulus');
print 'base64 modulus = ' . $modulus . "\n";

// To convert to hex:
$binDat->Clear();
$binDat->AppendEncoded($modulus,'base64');
$hexModulus = $binDat->getEncoded('hex');
print 'hex modulus = ' . $hexModulus . "\n";


?>