codemasher / php-threema

		$message = '';

		// @todo: check writable

		if(!empty($privateKeyFile) && is_dir(dirname($privateKeyFile))){

			file_put_contents($privateKeyFile, $keypair->privateKey);

			$message .= 'Private key saved to: '.$privateKeyFile.PHP_EOL;

		}

		if(!empty($publicKeyFile) && is_dir(dirname($publicKeyFile))){

			file_put_contents($publicKeyFile, $keypair->publicKey);

			$message .= 'Private key saved to: '.$privateKeyFile.PHP_EOL;

		}

		if(!empty($publicKeyFile) && is_dir(dirname($publicKeyFile))){

			file_put_contents($publicKeyFile, $keypair->publicKey);

			$message .= 'Public key saved to: '.$publicKeyFile.PHP_EOL;

		}

		return $message.PHP_EOL.'private:'.$keypair->privateKey.PHP_EOL.'public:'.$keypair->publicKey;

	}