ABSTRACT
Key distribution is one of the major problems in communication and network security. A key predistribution scheme (KPS) is a method by which a trusted authority (TA) distributes secret information among a set of users in such a way that every user in a group in some specified family of privileged subsets is able to compute a common key associated with that group. The key can be used for secure communication among the users in the group or can be used by the TA to send information privately to those users. In addition, certain coalitions of users (called forbidden subsets) outside a privileged subset must not be able to find out any information on the value of the key associated to that subset.
