A Study On Broadcast Encryption Schemes And Its Application

Broadcast encryption technology provides a way to send information to groups of authorized users in an unsecure tunnel. It is widely used in pay-TV, satellite broadcasting and telecommunications, digital rights products (such as CD/DVD) and multimedia distribution protection and so on.Currently broadcast encryption technology has made a lot of successful research, but there are still some problems that must be studied and improved in the aspects of safety, efficiency and practical applications. With existing theory and technology, to design safe and efficient broadcast encryption systems, to construct special broadcast encryption scheme for the growing application needing is necessary. In this paper, we present two new broadcast encryption schemes with studing the broadcast encryption technology, encryption system designing, key distribution technology and practical applications.Firstly, we make an in-depth analysis and extensive comparison on symmetric key and asymmetric key based broadcast encryption schemes. The communication overhead, storage size, computational complexity, and related security for the different kinds of broadcast encryption schemes is calculated and analysised. And the advantages and disadvantages of each scheme is concluded, which makes the research of broadcast encryption clear to understand.Secondly, we present a hierarchical identity-based broadcast encryption scheme based on the LWE(learning with errors)problem, a classic hard problem on lattices. In our scheme, each user’s identity is associated with a lattice matrix, then the relationship between the lattice and its sublattice could easily represent the hierarchical identy construction; short basis of a lattice is treated as a private key of a user, then based on the lattice delegation algorithm the private key for each level’s user can be derived. We also give the security proof for our scheme which is IND-CCA2secure against the attacks by outsider users and FS-CCA secure against the attacks by authorized receivers. Compared with the broadcast encryption scheme based on the bilinear mapping, our scheme is more efficient in the encryption and decryption. Then, we propose a CS-I broadcast encryption scheme which can be applied in the smart mobile terminals. The CS-I broadcast encryption scheme is composed of two function blocks, complete subset block and interval block. Taking advantage of each block, CS-I broadcast encryption scheme is more efficient than the former two. The security of the scheme and further problems needing to research are discussed at last of the section.Finally, we summarize and analyze the results achieved and the insufficient of the research. The vision for the future development of the broadcast encryption is discussed, too.