First information is divided into equal-size information pieces. Serial numbers are assigned to the information pieces, respectively. An encryption key is generated from a base number and a variable number varying for each of the information pieces. The base number is common to an information range managed by one licence. The first information is encrypted on a block-by-block basis in response to the encryption key to get encryption-resultant information for every predetermined minimum information unit smaller than the sizes of the information pieces. The encryption-resultant information is recorded on a recording medium. A determination is made as to logical addresses of heads of portions of the recording medium which are loaded with portions of the encryption-resultant information corresponding to the respective information pieces. Second information representing a correspondence relation between the determined logical addresses and the assigned serial numbers is recorded on the recording medium.