The application discloses a memory controller and a method for controlling an access to a memory module. The memory controller is coupled between the memory module and a host controller to control the access of the host controller to the memory module. The memory controller comprises: a central buffer coupled to the host controller for receiving data access command from the host controller and coupled to the memory module for providing an encrypted data access command to the memory module; wherein the central buffer comprises a command processing module, for performing encryption operation to a data access command with a predefined command encryption algorithm to generate an encrypted data access command; wherein a data channel is coupled between the memory module and the host controller, and wherein under the control of the encrypted data access command, the memory module exchanges data with the host controller via the data channel.