A method for accessing discrete data includes transmitting a write command to a memory, determining whether each data following a header of the file needs to be encrypted according to a data format of a file that is to be written into the memory, transmitting the file header and each data following the file header to a logic unit, turning on the logic unit for encrypting the data determined to be encrypted and writing the encrypted data into the memory, turning off the logic unit for writing the data determined not to be encrypted into the memory directly, and sending a first response signal from the memory when the writing of the file is finished.