(PHP ActiveX) Get a Certificate's Key Size

Demonstrates how to get the RSA key size of a certificate (for example, 1024-bit, 2048-bit, etc.)

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 this example, I have a certificate in raw base64 format (not PEM),
// that looks like this:  "MIIGkDCCBHigAwIBAgIUMDA ... s/iqLsLA=="
// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.StringBuilder')
$sbCertBase64 = new COM("Chilkat.StringBuilder");
$success = $sbCertBase64->LoadFile('qa_data/certs/base64Cert.txt','utf-8');

// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.Cert')
$cert = new COM("Chilkat.Cert");
$success = $cert->LoadFromBase64($sbCertBase64->getAsString());
if ($success != 1) {
    print $cert->LastErrorText . "\n";
    exit;
}

// Get the public key.
// pubKey is a Chilkat.PublicKey
$pubKey = $cert->ExportPublicKey();
if ($cert->LastMethodSuccess != 1) {
    print $cert->LastErrorText . "\n";
    exit;
}

// In Chilkat version v9.5.0.67, the KeySize property was added.
$numBits = $pubKey->KeySize;
print 'Number of bits = ' . $numBits . "\n";

// If using an older version of Chilkat, the key size can be obtained like this:
// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.Xml')
$xml = new COM("Chilkat.Xml");
$xml->LoadXml($pubKey->getXml());

// For versions of Chilkat < 10.0.0, use new COM('Chilkat_9_5_0.Chilkat.BinData')
$binDat = new COM("Chilkat.BinData");
$binDat->AppendEncoded($xml->getChildContent('Modulus'),'base64');

$numBits = 8 * $binDat->NumBytes;
print 'Number of bits = ' . $numBits . "\n";


?>