public function createPassphraseFile($passphrase, $passphraseFile, $privateKeyFile, $privateKeyPassphrase)
	{
		$privateKey = openssl_get_privatekey(file_get_contents($privateKeyFile), $privateKeyPassphrase);

		if (!$privateKey)
		{
			throw new \RuntimeException("Failed to load private key.");
		}

		$crypted = '';

		if (!openssl_private_encrypt($passphrase, $crypted, $privateKey))
		{
			throw new \RuntimeException("Failed to encrypt data using private key.");
		}

		return file_put_contents($passphraseFile, $crypted);
	}