Blind Expressive Ciphertext Policy Attribute Based Encryption for Fine Grained Access Control on the Encrypted Data

Oblivious transfer with access control is a protocol where data in the database server are protected with access control policies and users with credentials satisfying the access policies are allowed to access them, whereas the database server learns nothing about the data accessed by users or about her credentials.Our scheme has the advantages as follows: First, our scheme maintains the privacy property of oblivious transfer and offers access control mechanism. Second, it allows the expressive access control polices that directly supports AND, OR and Threshold gates. Third, the communication complexity in our scheme is constant in the numbers of records which have been accessed. Fourth, our scheme is constructed in prime order bilinear group.