A Time-Bound Key Management Scheme for Hierarchical Tree

Hierarchical tree structure is usually used for key management in complex information system. Differ- ent vertexes of the tree denote different security classes with distinct secret keys. Users in superior class can be allowed to decrypt the message belonging to the subordinating class. Commonly, the assigned key for a user needs to be changed in a period time. So it is a good solution to associate keys with time period. In this paper, we propose a new time-bound key man- agement scheme for hierarchy tree. Our scheme is very efficient because we still only use hash function in the key derivation and public information compu- tation process, and it is also secure under the existed attacks. Keywords: Cryptography, hierarchical, key manage- ment, time-bound, hash function