(Perl) 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 Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

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

$cert = chilkat::CkCert->new();
$success = $cert->LoadFromBase64($sbCertBase64->getAsString());
if ($success != 1) {
    print $cert->lastErrorText() . "\r\n";
    exit;
}

#  Get the public key.
# pubKey is a PublicKey
$pubKey = $cert->ExportPublicKey();
if ($cert->get_LastMethodSuccess() != 1) {
    print $cert->lastErrorText() . "\r\n";
    exit;
}

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

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

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

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