Security of tzeng's time-bound key assignment scheme for access control in a hierarchy
Xun Yi, Yiming Ye · IEEE Transactions on Knowledge and Data Engineering · 2003
Tzeng (2002) proposed a time-bound cryptographic key assignment scheme for access control in a partial-order hierarchy. In this paper, we show that Tzeng's scheme is insecure against the collusion attack whereby three users conspire to access some secret class keys that they should not know according to Tzeng's scheme.