/**
* Encrypt
*
* @param string $plaintext
* @param string $publicKey
* @return string
* @throws RuntimeException
*/
public function encrypt(string $plaintext, string $publicKey = '') : string
{
// generate a random session key
$sessionKey = random_bytes($this->symmetric->getKeySize());
// encrypt the plaintext with symmetric algorithm
$ciphertext = $this->symmetric->encrypt($plaintext, $sessionKey);
// encrypt the session key with publicKey
$encryptedKey = $this->public->encrypt($sessionKey, $publicKey);
// openssl_public_encrypt($sessionKey, $encryptedKey, $publicKey, $padding);
return base64_encode($encryptedKey) . ':' . $ciphertext;
}
