Abstract In this paper, we propose a resource‐efficient all‐or‐nothing oblivious transfer (OT) protocol for unknown single‐qubit unitary operations. To the best of our knowledge, this is the first construction of all‐or‐nothing OT for unknown unitary operations. In contrast to the trivial solution by combining all‐or‐nothing OT for classical messages and bidirectional quantum state teleportation, our protocol is more resource‐efficient, i.e., it only requires the consumption of two shared Bell states, two‐bit classical communication from Alice to Bob and at most one‐bit classical communication from Bob to Alice. In addition, the use of shared Bell states and simple quantum operations makes the proposed protocol feasible with current technology. Theoretical analysis and experimental simulation on IBM Qiskit simulator show the correctness of our protocol. Our results extend the application of OT protocols in privacy‐preserving distributed quantum computing.
Abstract In this paper, we propose a resource‐efficient all‐or‐nothing oblivious transfer (OT) protocol for unknown single‐qubit unitary operations. To the best of our knowledge, this is the first construction of all‐or‐nothing OT for unknown unitary operations. In contrast to the trivial solution by combining all‐or‐nothing OT for classical messages and bidirectional quantum state teleportation, our protocol is more resource‐efficient, i.e., it only requires the consumption of two shared Bell states, two‐bit classical communication from Alice to Bob and at most one‐bit classical communication from Bob to Alice. In addition, the use of shared Bell states and simple quantum operations makes the proposed protocol feasible with current technology. Theoretical analysis and experimental simulation on IBM Qiskit simulator show the correctness of our protocol. Our results extend the application of OT protocols in privacy‐preserving distributed quantum computing.
Oblivious transfer (OT) is an important tool in cryptography. It serves as a subroutine to other complex procedures of both theoretical and practical significance. A common attribute of OT protocols is that one party (Alice) has to send a message to another party (Bob) and has to stay oblivious to whether Bob did receive the message. Specific (OT) protocols vary by exact definition of the task---in the all-or-nothing protocol, Alice sends a single bit-string message, which Bob is able to read with only 50 probability, whereas in a 1-out-of-2 OT protocol Bob reads one out of two messages sent by Alice. These two flavors of protocol are known to be equivalent. Recently, a computationally secure all-or-nothing OT protocol based on quantum states was developed by A. Souto et al. [Phys. Rev. A 91, 042306 (2015)], which, however, cannot be reduced to a 1-out-of-2 OT protocol by standard means. Here we present an elaborate reduction of this protocol that retains the security of the original.
Abstract Oblivious transfer (OT) protocol is an essential building block for secure multiparty computation. The transmission of quantum messages is conductive in executing complex secure multiparty quantum computation tasks and even distributed quantum computation tasks. However, as an important form of OT protocol, existing all‐or‐nothing OT protocols only work for the transmission of classical messages thus limiting application scenarios. To tackle this issue, a counterfactual all‐or‐nothing OT protocol is proposed for quantum messages. Compared with existing all‐or‐nothing OT protocols for classical messages, the proposed protocol has three advantages: i) it is achieved without any physical particles traveling between the sender and the receiver thus reducing the communication complexity; ii) no prior entanglement between the sender and the receiver is required thus facilitating protocol implementation, and iii) it works for known even unknown quantum messages thereby offering broader application scenarios.
ABSTRACT Oblivious transfer (OT) is an important two‐party cryptographic primitive, and it is a universal building block for secure multiparty computation. In this paper, we for the first time introduce the notion of oblivious transfer for universal function (UFOT), where the sender Alice has two bits (, ) , and the receiver Bob obtains either the first bit , the second bit , or their function . Bob should not learn anything more than this, and Alice should not learn what Bob has learnt. To show the feasibility of this concept, we implement a quantum UFOT protocol based on oblivious quantum key distribution, and then analyze its security. We also show its advantages, such as lower cheating probabilities for two parties, loss tolerance, flexibility, and universality. It paves the way for solving privacy‐preserving machine learning problems.
In cryptography, oblivious transfer (OT) is an important multi-party cryptographic primitive and protocol, that is suitable for many upper-layer applications, such as secure computation, remote coin-flipping, electrical contract signing and exchanging secrets simultaneously. However, some no-go theorems have been established, indicating that one-out-of-two quantum oblivious transfer (QOT) protocols with unconditional security are impossible. Fortunately, some one-out-of-two QOT protocols using the concept of Crépeau’s reduction have been demonstrated not to conform to Lo’s no-go theorem, but these protocols require more quantum resources to generate classical keys using all-or-nothing QOT to construct one-out-of-two QOT. This paper proposes a novel and efficient one-out-of-two QOT which uses quantum resources directly instead of wasting unnecessary resources to generate classical keys. The proposed protocol is not covered by Lo’s no-go theorem, and it is able to check the sender’s loyalty and avoid the attack from the receiver. Moreover, the entangled state of the proposed protocol is reusable, so it can provide more services for the participants when necessary. Compared with other QOT protocols, the proposed protocol is more secure, efficient, and flexible, which not only can prevent external and internal attacks, but also reduce the required resources and resource distribution time.
Abstract The quest for perfect quantum oblivious transfer (QOT) with information‐theoretic security remains a challenge, necessitating the exploration of computationally secure QOT as a viable alternative. Unlike the unconditionally secure quantum key distribution (QKD), the computationally secure QOT relies on specific quantum‐safe computational hardness assumptions, such as the post‐quantum hardness of learning with errors (LWE) problem and quantum‐hard one‐way functions. This raises an intriguing question: Are there additional efficient quantum hardness assumptions that are suitable for QOT? In this work, leveraging the dihedral coset state derived from the dihedral coset problem (DCP), a basic variant of OT, known as the all‐or‐nothing OT, is studied in the semi‐quantum setting. Specifically, the DCP originates from the dihedral hidden subgroup problem (DHSP), conjectured to be challenging for any quantum polynomial‐time algorithms. First, a computationally secure quantum protocol is presented for all‐or‐nothing OT, which is then simplified into a semi‐quantum OT protocol with minimal quantumness, where the interaction needs merely classical communication. To efficiently instantiate the dihedral coset state, a powerful cryptographic tool called the LWE‐based noisy trapdoor claw‐free functions (NTCFs) is used. The construction requires only a three‐message interaction and ensures perfect statistical privacy for the receiver and computational privacy for the sender.
Oblivious transfer (OT) is an essential building block for secure multiparty computation. Up to now, one- and two-server OT protocols have been investigated. It has been proven that unconditionally secure one-server OT is impossible even with the quantum system. Recently, Hayashi and Song proposed the first two-server OT protocol for quantum messages [Adv. Quantum Technol. 7, 2300184 (2024)], which is the only one for two-server OT for quantum messages to our knowledge. This protocol has the assumption that two quantum servers do not communicate with each other. However, it is unrealistic to make such an assumption. In addition, an equation error occurs in the protocol description. To tackle these issues, we first point out the equation error existent in the protocol of Hayashi and Song and correct it. Then, we propose a two-server OT protocol for quantum messages by using entanglement swapping. Security analysis shows that the user privacy holds even if the two quantum servers communicate mutually.