Algebraic Analysis of Akl and Taylor Key Assignment Scheme
Khair Eddin Sabri · International Review on Computers and Software (IRECOS) · 2014
Key assignment schemes are used to distribute keys to users to enable them decrypt and view information. Usually users, based on their authority, are represented as a hierarchy such that a user can derive the keys of all users that have less authority. Several methods are exist in the literature to assign keys to users. However, some of them are not correct orvulnerable to collusion attacks such that two users can cooperate together to compute the key of a user at a higher level. One of the pioneer methods in key assignment is Akl and Taylor technique [1]. Several papers are introduced later based on their technique. In this paper, we analyze Akl and Taylor technique and its variations algebraically in terms of their correctness and the possibility of collusion attack. Furthermore, we introduce a new technique that is secure in a more restrictive assumption of collusion attack. We show that the proposed technique is more efficient than the existing ones.