On key distribution via true broadcasting

We consider true broadcast systems for the secure communication of session keys. These schemes provide for parallel rather than serial construction of broadcast messages, while avoiding selective broadcasting. We begin by introducing a conceptual framework for true broadcasting and illustrate its design with a secure key broadcast scheme based on probabilistic encryption. The framework provides for a system requiring user anonymity, as a result of the absence of addressing for the broadcast message. We also illustrate how Shamir’s threshold scheme can be altered to allow for parallel broadcasting. We then present a formal model and use information theoretic techniques to establish a lower bound on the size of the broadcast message for a class of true broadcast schemes. Finally, we improve upon the aforementioned threshold scheme such that it achieves the lower bound.