Abstract: A method for preventing a user from interpreting optional stored data information even when the user extracts the optional stored data, and an apparatus thereof. The apparatus for encrypting and processing data in a flash translation layer includes a flash memory and a controller. The flash translation layer searches at least one page of the flash memory storing the data when a write of optional data is requested from the controller, generates, corresponding to respective searched pages, a page key according to a predetermined encrypting function when the searched page supports an encryption, and encrypts and stores the data by the page key in the respective searched pages.