Airship\Engine\Cache\File::getRelativeHash PHP Method

    public static function getRelativeHash(string $preHash, bool $asString = false)
    {
        $state = State::instance();
        $cacheKey = $state->keyring['cache.hash_key'];
        if (!$cacheKey instanceof Key) {
            throw new InvalidType(\trk('errors.type.wrong_class', '\\ParagonIE\\Halite\\Key'));
        }
        // We use a keyed hash, with a distinct key per Airship deployment to
        // make collisions unlikely,
        $hash = \Sodium\crypto_generichash($preHash, $cacheKey->getRawKeyMaterial(), self::HASH_SIZE);
        $relHash = [\Sodium\bin2hex($hash[0]), \Sodium\bin2hex($hash[1]), \Sodium\bin2hex(Util::subString($hash, 2))];
        if ($asString) {
            return \implode(DIRECTORY_SEPARATOR, $relHash);
        }
        return $relHash;
    }