Where will those XML files be stored if the platform of this game is Web Player...?

Hi everyone, I am developing a game that has many important files, which are XML and are used to set the settings of the game. For an example, there will be a file that sets the amount of mana that a skill may consume and there will be another file that have the names and prices of the items that are used in the game. If these files are stored on the computers of the clients, they can cheat by modifying them.

Question: Where will those XML files be stored if the platform of this game is Web Player and streamed? Does it depends on the reading/loading method?