(PHP Extension) 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 PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux

<?php

include("chilkat.php");
// Use "chilkat_9_5_0.php" for versions of Chilkat < 10.0.0

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

$cert = new CkCert();
$success = $cert->LoadFromBase64($sbCertBase64->getAsString());
if ($success != true) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// Get the public key.
// pubKey is a CkPublicKey
$pubKey = $cert->ExportPublicKey();
if ($cert->get_LastMethodSuccess() != true) {
    print $cert->lastErrorText() . "\n";
    exit;
}

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

// If using an older version of Chilkat, the key size can be obtained like this:
$xml = new CkXml();
$xml->LoadXml($pubKey->getXml());

$binDat = new CkBinData();
$binDat->AppendEncoded($xml->getChildContent('Modulus'),'base64');

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


?>