Issuer-Free Adaptive Oblivious Transfer with Access Policy

Abstract

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.

Issuer-free oblivious transfer with access control revisited

“…We recall the ideal functionality F IOTAC for issuer-free OTAC proposed by Guleria and Dutta [5,6]. The difference between F IOTAC and the functionality F OTAC described in The latter difference creates a problem.…”

“…the receiver's attributes in order to attest whether the receiver indeed possesses those attributes. In contrast, in the security definition in [5,6], to protect receiver privacy, the sender learns neither the receiver's identity nor the receiver's attributes, and thus is not able to attest whether the receiver possesses the claimed attributes.…”

“…This has serious implications on the security of the protocols proposed in [5,6]. In those protocols, the sender always proceeds as if the receiver did possess those attributes without performing any check.…”

“…In Issuer-Free OTAC, the role of the issuer is performed by the sender. In this paper, we show that the security definition for issuer-free OTAC in [5,6] poses a problem. In a nutshell, the security definition for OTAC with public policies proposed by Camenisch et al [2] allows the issuer to learn the receiver's identity and http://dx.doi.org/10.1016/j.ipl.2017.05.006 0020-0190/© 2017 Elsevier B.V. All rights reserved.…”

“…Recently, Guleria and Dutta propose Issuer-Free OTAC with public policies [5,6]. In Issuer-Free OTAC, the role of the issuer is performed by the sender.…”