Oblivious transfer is a fundamental tool in cryptographic protocols, especially in secure two-party computation. In TCC 2011, Lindell and Pinkas proposed a variant called cut-and-choose oblivious transfer, which did a great job in solving the selective failure attack in secure two-party computation protocols based on cut-and-choose paradigm. In this paper, we present a new primitive called cut-and-choose bilateral oblivious transfer. As an extension to cut-and-choose oblivious transfer, in addition to overcoming the selective failure attack, this primitive also makes a contribution to reducing the round number of the protocols that invoke it. This is very important in the scenarios where interactions between parties are limited. Besides, the application of this primitive in the outer protocols enables us to present a more modular and clean high-level description of the protocol framework. Furthermore, we believe that the new primitive is of independent research interest itself and could be useful in many cut-and-choose scenarios. Based on homomorphic encryption, we construct an efficient instantiation of this primitive in malicious model, and present a formal rigorous proof of its security under ideal/real simulation paradigm.
Oblivious transfer is a fundamental tool in cryptographic protocols, especially in secure two-party computation. In TCC 2011, Lindell and Pinkas proposed a variant called cut-and-choose oblivious transfer, which did a great job in solving the selective failure attack in secure two-party computation protocols based on cut-and-choose paradigm. In this paper, we present a new primitive called cut-and-choose bilateral oblivious transfer. As an extension to cut-and-choose oblivious transfer, in addition to overcoming the selective failure attack, this primitive also makes a contribution to reducing the round number of the protocols that invoke it. This is very important in the scenarios where interactions between parties are limited. Besides, the application of this primitive in the outer protocols enables us to present a more modular and clean high-level description of the protocol framework. Furthermore, we believe that the new primitive is of independent research interest itself and could be useful in many cut-and-choose scenarios. Based on homomorphic encryption, we construct an efficient instantiation of this primitive in malicious model, and present a formal rigorous proof of its security under ideal/real simulation paradigm.
Oblivious transfer is a fundamental tool in cryptographic protocols, especially in secure two-party computation. In TCC 2011, Lindell and Pinkas proposed a variant called cut-and-choose oblivious transfer, which did a great job in solving the selective failure attack in secure two-party computation protocols based on cut-and-choose paradigm. In this paper, we present a new primitive called cut-and-choose bilateral oblivious transfer. As an extension to cut-and-choose oblivious transfer, in addition to overcoming the selective failure attack, this primitive also makes a contribution to reducing the round number of the protocols that invoke it. This is very important in the scenarios where interactions between parties are limited. Besides, the application of this primitive in the outer protocols enables us to present a more modular and clean high-level description of the protocol framework. Furthermore, we believe that the new primitive is of independent research interest itself and could be useful in many cut-and-choose scenarios. Based on homomorphic encryption, we construct an efficient instantiation of this primitive in malicious model, and present a formal rigorous proof of its security under ideal/real simulation paradigm.
Oblivious transfer is a fundamental tool in modern cryptography. It plays an important role in the research of security protocols. In recent years, many oblivious transfer variants with more powerful functionalities are proposed, so as to be fit in different kinds of requirements and scenarios. In this paper, a new oblivious transfer variant, called cut-and-choose bilateral oblivious transfer, is proposed. Based on homomorphic encryption, an efficient one-round protocol of this primitive is constructed, accompanied with rigorous security proof in semi-honest model. When applied in security protocols based on cut-and-choose technique (especially in secure two-party computation), cut-and-choose bilateral oblivious transfer enables a more modular high-level description of the protocol framework, as well as reduces the round complexity of the protocols. Besides, as a basic tool in the information security area, this primitive itself is of independent research interest.
Abstract. In secure two-party computation protocols, the cut-and-choose paradigm is used to prevent the malicious party who constructs the garbled circuits from cheating. In previous realization of the cut-and-choose technique on the garbled circuits, the delivery of the random keys is divided into multiple stages. Thus, the round complexity is high and the consistency of cut-and-choose challenge should be proved. In this paper, we introduce a new primitive called cut-and-choose bilateral oblivious transfer, which transfers all necessary keys of garbled circuits in one process. Specifically, in our oblivious transfer protocol, the sender inputs two pairs (x0, x1), (y0, y1) and a bit τ; the receiver inputs two bits σ and j. After the protocol execution, the receiver obtains xτ, yσ for j = 1, and x0, x1, y0, y1 for j = 0. By the introduction of this new primitive, the round complexity of secure two-party computation protocol can be decreased; the cut-and-choose challenge j is no need to be opened anymore, therefore the consistency proof of j is omitted. In addition, the primitive is of independent interest and could be useful in many cut-and-choose scenarios.
In secure two-party computation protocols based on garbled circuit, oblivious transfer (OT) plays an important role in transferring the garbled keys of the participants. In addition to the traditional OT primitive, many other variants of OT have also been presented, such as outsourced oblivious transfer (OOT), cut-and-choose oblivious transfer (CCOT), cut-and-choose bilateral oblivious transfer (CCBOT), etc. These new primitives significantly improve the efficiency and feasibility of secure two-party computation protocols, mainly in optimising computational complexity and interactive rounds. Among these primitives, CCBOT proposed by Zhao et al. in TrustCom 2015 is a novel one and helps to minimize the round complexity of the outer secure two-party computation protocols. In addition, they constructed a CCBOT protocol based on homomorphic encryption scheme in the malicious model. However, their protocol uses the cut-and-choose technique to guarantee security against malicious adversaries, as a result the protocol has an error probability. The commitment scheme is also inevitably involved in their protocol. In this paper, we present a CCBOT protocol with the security against malicious adversaries based on the Decisional Diffie-Hellman (DDH) assumption. Our proposed protocol avoids using the cut-and-choose technique and commitment scheme. In terms of efficiency, our protocol is much more efficient than the previous protocol.
Oblivious transfer is a fundamental tool in modern cryptography. In the past few years, many studies concentrate on oblivious transfer variants with more powerful functions. In this paper, the authors propose several variants of oblivious transfer in cut-and-choose scenario, providing multiple ways of transferring data in an oblivious manner. In addition, based on homomorphic encryption, the authors construct instantiations of these primitives, which can be proven secure in malicious model under ideal/real simulation paradigm and achieve the highest security level in the real world.
Protocols for secure two-party computation enable a pair of parties to compute a function of their inputs while preserving security properties such as privacy, correctness and independence of inputs. Recently, a number of protocols have been proposed for the efficient construction of two-party computation secure in the presence of malicious adversaries (where security is proven under the standard simulation-based ideal/real model paradigm for defining security). In this paper, we present a protocol for this task that follows the methodology of using cut-and-choose to boost Yao’s protocol to be secure in the presence of malicious adversaries. Relying on specific assumptions (DDH), we construct a protocol that is significantly more efficient and far simpler than the protocol of Lindell and Pinkas (Eurocrypt 2007) that follows the same methodology. We provide an exact, concrete analysis of the efficiency of our scheme and demonstrate that (at least for not very small circuits) our protocol is more efficient than any other known today. secure two-party computation, malicious adversaries, cut-and-choose, concrete effi-Keywords: ciency An extended abstract of this work appeared at TCC 2011.