HIERARCHICAL ENCRYPTION SCHEME FOR SECURE DISTRIBUTION OF PRESCRIBED CONTENTS

摘要

PROBLEM TO BE SOLVED: To provide a method for distributing an electronic data set of prescribed contents. SOLUTION: In the method for distributing the electronic data set expressing the prescribed contents, this method is provided with a process for dividing the electronic data set into a plurality of files. The first file expresses the version of the prescribed contents at least. The plurality of files are differently encrypted and distributed. Among the plurality of encrypted files, at least one encrypted file is selected to be decrypted on the basis of the level of desired quality. The selected encrypted file is decrypted by decryption keys peculiar for the level of the desired quality and the version of the prescribed contents is recovered.