An efficient key assignment scheme for access control in a hierarchy

Abstract

This paper examines a hash based hierarchical access control scheme proposed by Yang and Li. It is shown that the scheme suffers from the ex-member access problem. A new hash based scheme that avoids the ex-member problem is proposed. Our scheme has the following advantages: (i) it uses less private storage per node; (ii) addition or deletion of nodes and users does not require rekeying of all nodes; and (iii) the static version of the scheme carries a proof of security. A hash based scheme recently proposed by Atallah, Frikken and Blanton also has these properties. Compared to their scheme, our scheme requires less public storage space for tree hierarchies.