Patent ID: 7509179

Claim:
A distribution system that distributes a program for decoding encoded audio data, comprising: a distribution server device which sends the program and permission information which indicates that the program is permitted for use, in correspondence with the program; a removable memory unit which has an area for storing one or more programs which are each used for decoding encoded audio data of a different type; an acquisition device which, being connected to said distribution server device via a network and loaded with said removable memory unit, acquires the permission information and the program from said distribution server device and stores the permission information and the program in said removable memory unit, the permission information being stored in correspondence with the program; and an audio reproduction device which, being loaded with said removable memory unit storing the program, decodes the encoded audio data using the program, and outputs sounds, and said audio reproduction device stores a detection module beforehand, said detection module being a program module used for detecting a type of the encoded audio data, wherein the distribution system further generates a user identifier which identifies a user of said audio reproduction device, stores the generated user identifier, sends the generated user identifier, and also distributes maintenance information for updating the program, said acquisition device acquires the user identifier and stored the user identifier in said removable memory unit, reads the identifier from said removable memory unit, and sends the user identifier to said distribution server device, said distribution server device (a) stores the maintenance information beforehand in correspondence with the program, (b) receives the identifier,(c) judges whether the received user identifier matches the user identifier stored in said distribution server device, and (d) sends the maintenance information if the two user identifiers are judged as matching, and said acquisition device acquires the maintenance information, and updates the program stored in said removable memory unit using the acquired maintenance information, and said audio reproduction device detects the type of the encoded audio data using the detection module, reads the program for decoding encoded audio data of the detected type from said removable memory unit, and decodes the encoded audio data using the read program, and said audio reproduction device decodes the encoded audio data using the program, only when the permission information corresponding to the program is stored in said removable memory unit.