A Novel Bilateral Oblivious Transfer Protocol Based on Cut-and-Choose Technique

Abstract

The Yao’s protocol based on garbled circuits is the foundation of secure two-party computation protocols, and Oblivious Transfer (OT), as a important tool in modern cryptography, plays a crucial role in transmitting garbled keys in the Yao’s protocol. In the past decades, considerable attentions have been paid to the Cut-and-Choose technique which is applied to OT protocols to prevent malicious P 1 (called circuit generator) from constructing wrong garbled circuits. Additionally, Bilateral OT becomes a focus point, which can simultaneously transmit P 1 ’s and P 2 ’s (called circuit evaluator) garbled keys to guarantee input consistency of two parties and improve transmission efficiency. As can be seen, some Cut-and-Choose Bilateral OT (CCBOT) protocols have been proposed. Since CCBOT has emerged, the probability of malicious P 1 constructing wrong garbled circuits without being found becomes lower and the input consistency problem is properly resolved too. However, the security of most CCBOT protocols are facing challenges since they are based on the Decisional Diffie-Hellman (DDH) assumption, Quadratic Residues (QR) assumption and Decisional Composite Residuosity (DCR) assumption. In this paper, we present a novel CCBOT protocol with the security against malicious adversaries based on the Computational Diffie-Hellman (CDH) assumption, and analysize the correctness, efficiency and security of the constructed protocol. Besides, we analysize the cheating probability of P 1 in the CCBOT and extend the CCBOT to Single-Choice CCBOT to make the protocol more applicable.