public function deletePublicKey($keyId)
    {
        $fingerprint = $this->getFingerprint($keyId);

        if ($fingerprint === null) {
            throw new Crypt_GPG_KeyNotFoundException(
                'Public key not found: ' . $keyId,
                self::ERROR_KEY_NOT_FOUND,
                $keyId
            );
        }

        $operation = '--delete-key ' . escapeshellarg($fingerprint);
        $arguments = array(
            '--batch',
            '--yes'
        );

        $this->engine->reset();
        $this->engine->setOperation($operation, $arguments);
        $this->engine->run();
    }