Adaptively Secure Broadcast Encryption With Constant Ciphertexts

In this paper, we present a new public key broadcast encryption (BE) for achieving adaptive security against arbitrary number of colluders. Specifically, our scheme is built from composite order multilinear maps and enjoys ciphertext overhead of a constant number of group elements which are O (1) bits. Furthermore, the private key size and public key size are all poly-logarithmic in the total number of users. Herein, we generalize the methodology of Lewko and Waters for realizing dual system encryption to the composite order multilinear groups, and then prove the adaptive security of our scheme under static assumptions in the standard model. Compared with the state-of-the-art, our scheme achieves the adaptive security in simple and non-interactive falsifiable assumptions with the optimized parameter size for BE.