An Improved Time-Bound Hierarchical Key Assignment Scheme
Qingyu Xu, Mingxing He, Lein Harn · 2008
Recently, Chien [1] proposed a time-bound hierarchical key assignment scheme based on tamper-resistant devices. Chein's scheme greatly reduces computation load and implementation cost. However, it has a security weakness against X. Yi's three-party collusion attack [2]. 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 Chein's. Finally, we have made an experiment to verify our conclusion.