| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an information processing apparatus and a method thereof capable of reducing calculation processing for calculating a node key corresponding to each of nodes on a path from a root to the leaf to which its own device belongs to, in processing of providing encryption data such as a key of cryptograph to which a hierarchical tree structure is applied. <P>SOLUTION: The encryption data providing processing to which the hierarchical tree structure is applied has a structure in which trap-door one-way permutation F<SB>i</SB>and reverse permutation F<SP>-1</SP><SB>i</SB>are applied to calculation processing and setting processing of each of the nodes in an a-branch tree (HKT), and execution of the trap-door one-way permutation F<SB>i</SB>by the number of times equivalent to the length of the height of a tree at the maximum can complete node key calculation in the calculation of a node key in each device. By repeating execution of the trap-door one-way permutation F<SB>i</SB>by using a key held in the device, the node key in an upper node can be sequentially calculated. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
