CONTENTS AUTHENTICATION SYSTEM AND METHOD, AND RECORDING MEDIUM

PROBLEM TO BE SOLVED: To provide a contents authentication system or the like for attaining the utilization of contents while preventing disordered duplication and smoothly authenticating the utilization of the contents on the line of low speed/small capacity. SOLUTION: An image display terminal 3 supplies the image ID of an image desired to utilize to a contents server 1 together with its own identification code. The contents server 1 supplies the image data expressing this image to the image display terminal 3 in the state of enciphering the image data with a cryptographic key and transfers the image ID and the identification code of the image display terminal 3 to a license server 2. The license server 2 supplies the cryptographic key for deciphering the image data shown by the transferred image ID to the image display terminal 3 shown by the transferred identification code. The image display terminal 3 acquires the cryptographic key from the license server 2 and stores it in the state of making the specification of contents difficult for a user. Then, the image data are deciphered by this cryptographic key and reproduced in the state of making preservation difficult.