Security of Tzeng's time-bound key assignment scheme for access control in a hierarchy
In [1], Tzeng 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.
key assignment access control collusion attack rsa