Efficient ciphertext policy attribute based encryption under decisional linear assumption

We propose a new Ciphertext Policy Attribute Based En-

cryption (CP-ABE) scheme where access structures are de-

ned by AND-Gates with wildcards. One major dierence

between our scheme and the existing ones is that we can

use a single element to represent one attribute, while the

previous schemes require three dierent elements to repre-

sent the three possible values (namely positive, negative,

and wildcard) of an attribute. Our proposed scheme also

achieves both constant-size ciphertext and constant num-

ber of decryption operations, and is proven secure under the

standard Decision Linear Assumption.