RSA accumulator based broadcast encryption

Abstract

Broadcast encryption schemes allow a center to transmit encrypted data over a broadcast channel to a large number of users such that only a select subset of privileged users can decrypt it. In this paper, we analyze how RSA accumulators can be used as a tool in this area. First, we describe a technique for achieving full key derivability given any broadcast encryption scheme in the general subset-cover framework [16]. Second, we show that Asano's Broadcast Encryption scheme [5], can be viewed as a special-case instantiation of our general technique. Third, we use our technique to develop a new stateless-receiver broadcast encryption scheme that is a direct improvement on Asano's scheme with respect to communication complexity, amount of tamper-resistant storage needed, and key derivation costs. Fourth, we derive a new lower bound that characterizes the tradeoffs inherent in broadcast encryption schemes which use our key derivability technique. © Springer-Verlag 2004.