A cryptographic key assignment scheme for access control in a hierarchy with exceptions

Abstract

Hierarchy is a critical issue in the access control policy for information protection systems. There are many cryptographic key assignment schemes that were proposed to solve the access control problem in a hierarchy. But some distributed systems need more complex access control policies that can not be expressed in the hierarchy model. Recently, Yeh et al. proposed a cryptographic key assignment scheme, which enforces access control policies in a hierarchy with the transitive and the anti-symmetric exceptions. Unfortunately, in 2000, Hwang has shown that Yeh et al.’s scheme is not secure against a cooperative attack. This article presents a secure cryptographic key assignment scheme for access control policies in a hierarchy with exceptions, which can withstand the Hwang’s cooperative attack. Meanwhile, it also provides an effective and dynamic method to generate, derive and update the secret keys and the public values.