ParagonIE\Halite\File::unsealData PHP 메소드

    protected static function unsealData(ReadOnlyFile $input, MutableFile $output, EncryptionSecretKey $secretKey) : bool
    {
        $publicKey = $secretKey->derivePublicKey();
        // Is the file at least as long as a header?
        if ($input->getSize() < Halite::VERSION_TAG_LEN) {
            throw new InvalidMessage("Input file is too small to have been encrypted by Halite.");
        }
        // Parse the header, ensuring we get 4 bytes
        $header = $input->readBytes(Halite::VERSION_TAG_LEN);
        // Load the config
        $config = self::getConfig($header, 'seal');
        if ($input->getSize() < $config->SHORTEST_CIPHERTEXT_LENGTH) {
            throw new InvalidMessage("Input file is too small to have been encrypted by Halite.");
        }
        // Let's grab the public key and salt
        $ephPublic = $input->readBytes($config->PUBLICKEY_BYTES);
        $hkdfSalt = $input->readBytes($config->HKDF_SALT_LEN);
        // Generate the same nonce, as per sealData()
        $nonce = \Sodium\crypto_generichash($ephPublic . $publicKey->getRawKeyMaterial(), '', \Sodium\CRYPTO_STREAM_NONCEBYTES);
        // Create a key object out of the public key:
        $ephemeral = new EncryptionPublicKey(new HiddenString($ephPublic));
        $key = AsymmetricCrypto::getSharedSecret($secretKey, $ephemeral, true);
        unset($ephemeral);
        list($encKey, $authKey) = self::splitKeys($key, $hkdfSalt, $config);
        // We no longer need the original key after we split it
        unset($key);
        $mac = \Sodium\crypto_generichash_init($authKey);
        \Sodium\crypto_generichash_update($mac, $header);
        \Sodium\crypto_generichash_update($mac, $ephPublic);
        \Sodium\crypto_generichash_update($mac, $hkdfSalt);
        $oldMACs = self::streamVerify($input, Util::safeStrcpy($mac), $config);
        // We no longer need this:
        \Sodium\memzero($hkdfSalt);
        $ret = self::streamDecrypt($input, $output, new EncryptionKey(new HiddenString($encKey)), $nonce, $mac, $config, $oldMACs);
        unset($encKey);
        unset($authKey);
        unset($nonce);
        unset($mac);
        unset($config);
        unset($oldMACs);
        return $ret;
    }