Ciphertext-policy attribute-based encryption with hiding access structure

Ciphertext-policy attribute based encryption (CP-ABE) is becoming very significant in distributed computing environment. Distributed computing environment is very popular way of storing and distributing information, because it is easy to store some information at one place and distribute the information from there. In CP-ABE scheme, every information is encrypted under an access structures, this access structures defines, who can access the encrypted information. But in CP-ABE scheme, we also store access structures along with encrypted information and sometimes this access structures can reveal many things about the plaintext information and the decryptor, therefore any adversary can learn many things. Therefore, it is appropriate to have CP-ABE scheme in which the access structures are not public means access structures are hidden from the users. We have proposed one scheme, in which users do not store access structures with encrypted information (ciphertext). We have used composite-order bilinear groups in our scheme.