In a manufacturing process of a continuous linear velocity (CLV) storage medium, a method for rendering a file stored on the CLV storage medium immunized against an unauthorized duplication. The CLV includes a plurality of consecutive blocks, each including a data section and control section. The control section includes an error correction and an error detection code. The blocks are configured in a given format. The method includes the steps of: (a) modifying a portion of the data section in a block so as to constitute modified data section. The modified data constitutes reconfigured format which violates the given format. The method further includes the step of modifying the control section that is associated with the modified data section, such that the error correction and error detection codes match the modified data section.