Encrypting a password with a self-signed certificate

PinEncryption.php

<?php
/**
*
* @param $password A user defined password
* @return string
*
*/
public function encryptPasswordToRsaBase64(string $password): string
{
    $publicKey = fopen('/path/to/public/key.pem', 'r');
    $publicKeyString = fread($publicKey, 8192);
    fclose($publicKey);

    openssl_get_publickey($publicKeyString);
    openssl_public_encrypt($password, $encryptedPin, $publicKeyString);

    return (string) base64_encode($encryptedPin);
}