Generate PEM-Encoded PKCS#1 Format RSA Key Pair using PHP

phpseclib library

1. Add phpseclib library to composer.json file:

"require": {
    "phpseclib/phpseclib": "^3.0"
}

2. Install library from the command line:

composer install

3. Generate PEM-encoded PKCS#1 format RSA key pair:

<?php

use phpseclib3\Crypt\RSA;

require_once __DIR__.'/vendor/autoload.php';

$keySize = 2048;

$privateKey = RSA::createKey($keySize);
$publicKey = $privateKey->getPublicKey();

$privateKey = $privateKey->toString('PKCS1');
$publicKey = $publicKey->toString('PKCS1');

echo $privateKey.PHP_EOL;
echo $publicKey.PHP_EOL;