Oblivious Transfer with Hidden Access Control from Attribute-Based Encryption
The notion of oblivious transfer with Hidden Access COnTrol policies (HACOT) was recently proposed by Camenisch et al. (Public-Key Cryptography 2011). This primitive allows a user to anonymously query a database where each record is protected by a hidden attribute-based access control policy. At each query, the user either learns the value of a single record if the attributes in his key satisfy the policy, or the mere fact that his attributes do not satisfy the policy. The database, even when colluding with the key issuer, learns nothing about the identity of the user, the index or the access policy of the record, or whether access was granted or denied.