Broadcast Encryption for Differently Privileged

Broadcast encryption is a primary technology that has been used for content protection. It enables a broadcaster to distribute content to a set of users so that only a privileged subset of users can access the content and another subset of revoked users cannot access the content. The main enabling block in a broadcast encryption scheme is the session key block, which each authorized user processes differently, but each gets the same valid session key. Currently all existing broadcast encryption schemes have assumed that the content and authorized users are equally privileged. There are emerging scenarios that demand protection for content with different privileges and for users with different privileges. In this paper we shall present a new broadcast encryption scheme that continues to employ single session key blocks but provides different privileged protections for different content and users. In particular we will expand the elegant subset-cover-based broadcast encryption scheme. We shall introduce a new concept called “security class” into the session key blocks. We use keys derived from a chain of one-way functions. Our approach is simple, efficient and secure.