PHP Extension

Duplicate openssl pkey -in private.pem -pubout -out pubkey.pem

See more OpenSSL Examples

How to output the public part of a private key: Demonstrates how to duplicate this OpenSSL command:

openssl pkey -in private.pem -pubout -out pubkey.pem

PHP Extension

<?php

include("chilkat.php");

$success = false;

$pkey = new CkPrivateKey();

// Load the private key from an PEM file:
$success = $pkey->LoadPemFile('private.pem');
if ($success == false) {
    print $pkey->lastErrorText() . "\n";
    exit;
}

$pubKey = new CkPublicKey();
$pkey->ToPublicKey($pubKey);

$success = $pubKey->SavePemFile(false,'pubKey.pem');
if ($success != true) {
    print $pubKey->lastErrorText() . "\n";

    exit;
}

print 'Success.' . "\n";

?>