| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a constitution for reducing an information amount stored in equipment which decodes a ciphered sentence in a ciphered sentence providing constitution to which a tree structure based on an SD system is applied. <P>SOLUTION: Among labels corresponding to respective subsets set on the basis of the SD system or an LSD system, an intermediate label enabling a label corresponding to a special subset calculated by an arithmetic operation is set, and other intermediate labels can be calculated by applying trapdoor one-way permutation F based on the value of one intermediate label. A receiver provides the label not corresponding to the special subset and one intermediate label. The receiver calculates the other intermediate labels by executing the trapdoor one-way permutation F to the held intermediate label and calculates all the required labels. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
