Recently, Chien proposed a time-bound hierarchical key assignment scheme based on tamper-resistant devices. Chien's scheme greatly reduces computation load and implementation cost. However, it has a security weakness against X. Yi's three-party collusion attack. In this paper, we improved Chien's scheme without public key cryptography and our scheme is resistant to X. Yi's three-party collusion attack. The most important is that our scheme is as efficient as Chien's. Finally, we have made an experiment to verify our conclusion.
['Qingyu Xu', 'Mingxing He', 'Lein Harn']
An Improved Time-Bound Hierarchical Key Assignment Scheme