$generator = new KeyGenerator();
$privateKey = $generator->generate();

$generator = new KeyGenerator();
$generator->setBits(2048);
$privateKey = $generator->generate();

$privateKey = PrivateKey::loadFromFileName('privatekey.pem');

$encrypted = $privateKey->encrypt('Hello World');

$publicKey = $privateKey->getPublicKey();

$publicKey->decrypt($encrypted);

$ composer require blar/openssl

$ git clone https://github.com/blar/openssl.git