A CRYPTOGRAPHIC KEY ASSIGNMENT SCHEME FOR IMPROVING THE INCORRECTNESS OF CHW SCHEME

Abstract

Based on the Newton interpolation method and a prede¯ned one-way function, a cryptographic key assignment scheme, called the CHW scheme, in a user hierarchy was presented by Chang et al. in 1992 [4]. The CHW scheme solved the need of the dramatic storage in Akl-Taylor scheme [1]. However, two counter examples presented in [6] prove the incorrectness of CHW scheme, and further two modi¯ed versions of CHW scheme [8] are proven to be insecure as well. Owing to the above-mentioned problems, in this paper a simple scheme is proposed to solve the incorrectness and to enhance the security of CHW scheme.