(PHP ActiveX) Convert RSA Private Key to Public Key

Demonstrates how to get a public RSA key from a private RSA key.

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')
$key = new COM("Chilkat.PrivateKey");

// Step 1: Load the private key from a source.
// (Chilkat can load private keys from all types of formats, and from in-memory bytes or encoded strings.
// see the online reference documentation for more options.)
$success = $key->LoadPemFile('qa_data/pem/VP_Private.pem');
if ($success != 1) {
    print $key->LastErrorText . "\n";
    exit;
}

// Step 2: Get the public key object from the private key object.
// pubKey is a Chilkat.PublicKey
$pubKey = $key->GetPublicKey();
if ($key->LastMethodSuccess != 1) {
    print $key->LastErrorText . "\n";
    exit;
}

// Step 3: Save the public key in a desired format. 
// (Chilkat can load or save public and private keys in many different formats.  See
// the online reference documentation for more options.)

// Saves to a PKCS8 PEM file.
$bPreferPkcs1 = 0;
$success = $pubKey->SavePemFile($bPreferPkcs1,'qa_data/pem/VP_Public.pem');
if ($pubKey->LastMethodSuccess != 1) {
    print $pubKey->LastErrorText . "\n";
    exit;
}

print 'Extracted and saved public key from private key.' . "\n";

?>