| 摘要 |
An image distribution system is provided to set or manage keys effectively by encoding and decoding data through hierarchical keys in distributing the data of a coded image and to set plural keys even for an apparatus equipped with a memory having small capacity storing the keys. An image distribution system for distributing data of a coded image sets the top key and then sets at least one element, for generating the key ranked lower than the top key, and the order of the elements. The data is coded and decoded by using the bottom key obtained by a method using the hierarchical key obtained in generating the lower key from the top key by using the elements one by one according to the order of the elements. |
