DEVICE AND METHOD FOR CIPHERING DIGITAL FILE, AND RECORDING MEDIUM THEREFOR

摘要

PROBLEM TO BE SOLVED: To prevent a digital data file from unauthorizedly flowing out without additionally increasing its price in the case of decoding a digital data file such as MP3 downloaded from a server side and downloading the decoded file to a digital data player side. SOLUTION: This digital data file ciphering device is constituted so that highly ciphered digital data and a ciphering key are received and stored, the stored ciphered digital data are deciphered by using the ciphering key, the deciphered digital data are stored in a buffer 124 in each prescribed unit, and the digital data outputted from the buffer 124 are ciphered to a low level and downloaded to a digital data player 130 or a storage medium 140.