1. An apparatus for preventing replay attacks, the apparatus comprising: a terminal including a storage medium and a central processing unit (CPU), the storage medium having a plurality of instruction units stored thereon configured for being executed by the CPU to perform operations, the plurality of instruction units including: an acquisition unit for, when a request for operating a digital content is received, acquiring current location information of a set of placeholder files in the storage medium of the terminal; a determination unit for determining whether the current location information is consistent with recorded location information of the placeholder file in the storage medium of the terminal, wherein the current location information is consistent with the recorded location information when the current location information is the same as the recorded location information, and the current location information is inconsistent with the recorded location information when the current location information is different than the recorded location information, and an operation on the digital content is permitted when the determination unit determines consistency; a protection unit for, when the determination unit determines inconsistency, preventing the operation on the digital content; a moving unit, for moving the location of the set of placeholder files in the storage medium of the terminal and modifying sizes of the set of placeholder files that is moved, after the operation on the digital content; and an update unit, for, in response to movement of the location of the set of placeholder files, updating the current location information of the set of placeholder files and defining new location information according to the movement of the location of the set of placeholder files, wherein the new location information is used as the recorded location information in a subsequent determination of the determination unit, wherein there is a correspondence between the digital content and the set of placeholder files in the storage medium of the terminal.