| 摘要 |
PROBLEM TO BE SOLVED: To enable coping with plural different cipher systems with a relatively small number of hardwares and also to enable coping with a new cipher system which is to be proposed in future without changing hardwares. SOLUTION: A cipher decoding part 123 has a memory area in which plural cipher decoding algorithms are preliminarily stored and a memory area for storing the cipher decoding algorithm read out from a medium 1. When the encryption information recorded on the medium 1 are decodable by the cipher decoding algorithms which are preliminarily stored in the cipher decoding part 123, a control part 124 selects the algorithm and, on the other hand, when the encryption information is not decodable, it sets the cipher decoding algorithm read out from the medium 1 to the cipher decoding part 123 based on 'medium format information' indicating the kind or the data structure of a medium, recording formats of encryption or the like and a cipher decoding algorithm being in read-out data. |
