PROBLEM TO BE SOLVED: To solve the problems of a conventional encryption decryption device that has had the increased scale of required circuits and memory capacity in proportion to the number of recording media and of attributes of contents because of provision of the number of encryption means corresponding simply to the strength of encryption and that cannot have executed a plurality of encryption and/or decryption processes at the same time.;SOLUTION: An encryption/decryption section 20 applies encryption to program data (a) with the strongest encryption strength and uses a decoding section 203 being part thereof to decode encrypted contents data (b). The decoding processing time by the decoding section 203 is selected to be a half of the processing time by other encryption sections 201, 205, the encryption section 201 applies encryption processing to program data a[i+1] and the encryption section 205 applies encryption processing to program data a[i-1] at the same time of decoding processing of program data a[i] or contents data b[i] by the decoding section 203 so as to attain the decoding processing of data with different encryption strength at the same time of the encryption processing.;COPYRIGHT: (C)2003,JPO
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