| 摘要 |
It relates to an information processing unit, a terminal unit, an information processing method, a key generation method and a program that enable reduction of the number of keys to be held by users and aims at providing an information processing unit capable of generating a directed-graph representing an encryption key generation logic to derive a set-key for encrypting a content or a content-key. The technique relates to a scheme that divides a set of user terminals into some subsets, allocates a set-key and an intermediate-key to each subset, and upon input of an intermediate-key correlated with a subset, outputs the set-key corresponding to the subset and the intermediate-key of the subset associated by the directed-edge. Further, it relates to a technique of replacing the directed-edge in the directed-graph with a shorter directed-edge. The effect of reducing the number of intermediate-keys held by each user is expected from the technique.
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