Abstract: The invention is a portable storage device and a data security-control method thereof. The portable storage device has a controller, a non-volatile memory and a communication port. The non-volatile memory and the communication port are connected to the controller. The non-volatile memory has a data storage area and a cache area. The controller executes a data caching function through the cache area to increase data accessing speed. When the communication port is connected to a host, the controller determines whether the host loads a data security-control driver. If the host does not load the data security-control driver, a permission of the host for assessing the non-volatile memory is restricted. The non-volatile memory is then protected from erroneous data accessing to assure data security.

Abstract: A read-only protection method for removable storage medium has steps of establishing a copy prohibited list, receiving a write command for the removable storage medium, determining whether to allow duplication of data to the removable storage medium, allowing duplication of data to the removable storage medium when the data to be duplicated are not listed in the copy prohibited list and prohibiting duplication of data to the removable storage medium when the data to be duplicated are listed in the copy prohibited list. The method of the present invention prohibits copying of pre-designated data to the removable storage medium, but writing other data is allowed.