| 摘要 |
PROBLEM TO BE SOLVED: To provide an encoding device for making code length short and achieving a more practical coding system by improving Tardos code. SOLUTION: The encoding device 1 generates a code word which is different for each user and embedded in digital data in order to track, with a tracking device 4, a user of illegally used digital data from falsified data remaining in illegal digital data created in collusion. The encoding device 1 includes: an optimum Z calculating section 11 for generating, by calculation, a plurality of candidates of a threshold value to be used for the judgement for tracking the illegal person with the tracking device 4; an optimum code length calculating section 12 for acquiring, by calculation, a plurality of code length values respectively corresponding to the generated candidates of the threshold value, and selecting the minimum value out of the plurality of code length values; and a code word generating section for generating, with the code length of the selected value, a code word different for each user. COPYRIGHT: (C)2007,JPO&INPIT |
