Reducing storage at receivers in SD and LSD broadcast encryption schemes

Abstract

A broadcast encryption scheme allows a sender to send information securely to a group of receivers while excluding other designated receivers over a broadcast channel. The most efficient methods currently proposed are the Subset Difference (SD) method and the Layered Subset Difference (LSD) method. In these methods, each receiver must store O (log2 N) and O (log 1+ε N) labels, respectively, where N is the total number of receivers and ε is an arbitrary number satisfying ε > 0. In this paper we apply the Master Key technique to the SD and LSD methods in order to reduce the number of labels a receiver stores by log N in exchange for an increase in the computational overhead. In order to reduce a receiver's memory requirements in another modification, we apply a version of the Complete Subtree method using trapdoor one-way permutations to the SD and LSD methods. © Springer-Verlag 2004.