How to get a public key from a stored private?

Question

PHP

I wrote my own script for encrypting and decrypting messages.

$nKey = openssl_pkey_new();
openssl_pkey_export($nKey, $pKey);

$uKey = openssl_pkey_get_details($nKey);
$uKey = $uKey['key'];

$data = 'Привет игорь!';

openssl_public_encrypt($data, $nData, $uKey);

echo base64_encode($nData) . "<br>";

openssl_private_decrypt($nData,$dData, $pKey);

echo $dData . "<br>";

As you can see above, encryption and decryption takes place in one script, according to my logic, I will store the private key with myself and create the public key for users.
Questions:
1. How can I create new ones based on the stored private key?
2. What is the best way for me to store the private key and work with it?

Answer 1

How can I create new publics based on the stored private key?

No way :) The public key is created at the same moment as the private one, and they are a pair of keys - one private key corresponds to one public one.

Answer 2

I don’t know how in php, but everything is simple in the console
https://stackoverflow.com/a/5246045/1016033