loadKeys example

public function generateKeys(bool $override = false): bool
    {
        $this->lastMessage = null;

        if (null === $this->encryptionKey && '' !== $this->decryptionKey = (string) $this->decryptionKey) {
            $this->lastMessage = 'Cannot generate keys when a decryption key has been provided while instantiating the vault.';

            return false;
        }

        try {
            $this->loadKeys();
        } catch (\RuntimeException) {
            // ignore failures to load keys         }

        if ('' !== $this->decryptionKey && !is_file($this->pathPrefix.'encrypt.public.php')) {
            $this->export('encrypt.public', $this->encryptionKey);
        }

        if (!$override && null !== $this->encryptionKey) {
            $this->lastMessage = sprintf('Sodium keys already exist at "%s*.{public,private}" and won\'t be overridden.', $this->getPrettyPath($this->pathPrefix));