public function verifySignature($plaintext, $signature, $fingerprint)
    {
        if ($fingerprint === null || !isset($this->keys[$fingerprint])) {
            throw new InvalidKeyPairIdException('Invalid keypair fingerprint given', 1304959763);
        }

        $verifyResult = openssl_verify($plaintext, $signature, $this->getPublicKey($fingerprint)->getKeyString());

        return $verifyResult === 1;
    }