ParagonIE\Halite\File::decryptData PHP Method

    protected static function decryptData(ReadOnlyFile $input, MutableFile $output, EncryptionKey $key) : bool
    {
        // Rewind
        $input->reset(0);
        // Make sure it's large enough to even read a version tag
        if ($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, 'encrypt');
        // Is this shorter than an encrypted empty string?
        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 first nonce and salt
        $firstNonce = $input->readBytes($config->NONCE_BYTES);
        $hkdfSalt = $input->readBytes($config->HKDF_SALT_LEN);
        // Split our keys, begin the HMAC instance
        list($encKey, $authKey) = self::splitKeys($key, $hkdfSalt, $config);
        // VERSION 2+
        $mac = \Sodium\crypto_generichash_init($authKey);
        \Sodium\crypto_generichash_update($mac, $header);
        \Sodium\crypto_generichash_update($mac, $firstNonce);
        \Sodium\crypto_generichash_update($mac, $hkdfSalt);
        $old_macs = self::streamVerify($input, Util::safeStrcpy($mac), $config);
        \Sodium\memzero($authKey);
        \Sodium\memzero($hkdfSalt);
        $ret = self::streamDecrypt($input, $output, new EncryptionKey(new HiddenString($encKey)), $firstNonce, $mac, $config, $old_macs);
        unset($encKey);
        unset($authKey);
        unset($firstNonce);
        unset($mac);
        unset($config);
        unset($old_macs);
        return $ret;
    }