Efficient Dynamic Broadcast Encryption and Its Extension to Authenticated Dynamic Broadcast Encryption

Abstract

We propose two public-key broadcast encryption schemes. Our Scheme1 is a variant of the dynamic broadcast encryption scheme proposed by Delerablée et al.[9]. The computational cost and the encryption (public) key size are more efficient than the original scheme. We observe that by using a decryption key in the original scheme, we can encrypt a message more efficiently without a part of an encryption key. In order to let any user receive this benefit, we introduce a “dummy key” which is similar to a decryption key. Scheme2 is an extension of Scheme1 to achieve an authenticated dynamic broadcast encryption scheme that enables receivers to verify the producer of broadcasted content. In Scheme2, we adopt the signature scheme proposed by Barreto et al. [3]. To our knowledge, Scheme2 is the first scheme that achieves provable security for broadcast encryption and signature with common parameters and keys.