Anonymous identity-based broadcast encryption with adaptive security
Anonymous identity-based encryption(IBE) can be used to build Public-Key Encryption with Keyword Search. But no efficient previous works in the identity-based broadcast encryption are known. In this paper, we extend the anonymous IBE definition to the identity-based broadcast encryption. Then a new construction of anonymous identity-based broadcast encryption is proposed in the standard model. In the new construction, the ciphertexts and private keys are indistinguishable for the different receivers set. The proposed scheme has constant size ciphertexts and achieves adaptive security. In addition, the security of the proposed scheme is reduced to the static assumptions in a composite group.