  Privacy is a major concern in designing any cryptographic primitive when
frequent transactions are done electronically. During electronic transactions,
people reveal their personal data into several servers and believe that this
information does not leak too much about them. The adaptive oblivious transfer
with hidden access policy (AOT-HAP) takes measure against such privacy issues.
The existing AOT-HAP involves a sender and multiple receivers apart from a
designated issuer. Security of these schemes rely on the fact that the issuer
cannot collude with a set of receivers. Moreover, they loose security when run
with multiple protocol instances during concurrent execution. We present the
first issuer-free AOT-HAP in universal composable (UC) framework in which the
protocol is secure even when composed with each other or with other protocols.
A concrete security analysis is given assuming the hardness of q-strong
Diffie-Hellman (SDH), decision Linear (DLIN) and decision bilinear
Diffie-Hellman (DBDH) problems against malicious adversary in UC model.
Moreover, the protocol outperforms the existing similar schemes.
