Oblivious transfer (OT) is a fundamental primitive in cryptography. It is known that unconditionally secure OT is impossible, even with the help of quantum mechanics. Furthermore, no classical OT scheme has been proven to offer computational security in the usual super-polynomial model, and there is evidence that such schemes cannot be based on one-way permutations. Nevertheless, inspired by Ralph Merkle's 1974 key distribution scheme, we offer a novel classical OT scheme based on one-way permutations and prove its polynomial security: the effort to cheat it scales as t3/2, where t is the legitimate effort needed to implement it. Unfortunately, our scheme melts down under the onslaught of a quantum adversary after an effort merely in the order of t5/6, so that it is actually easier to subvert it than to use it legitimately! By allowing the honest parties to use quantum computation as well, however, it may be that our OT scheme can be repaired so as to resist modest quantum attacks.
Oblivious transfer (OT) is a fundamental primitive in cryptography. It is known that unconditionally secure OT is impossible, even with the help of quantum mechanics. Furthermore, no classical OT scheme has been proven to offer computational security in the usual super-polynomial model, and there is evidence that such schemes cannot be based on one-way permutations. Nevertheless, inspired by Ralph Merkle's 1974 key distribution scheme, we offer a novel classical OT scheme based on one-way permutations and prove its polynomial security: the effort to cheat it scales as t3/2, where t is the legitimate effort needed to implement it. Unfortunately, our scheme melts down under the onslaught of a quantum adversary after an effort merely in the order of t5/6, so that it is actually easier to subvert it than to use it legitimately! By allowing the honest parties to use quantum computation as well, however, it may be that our OT scheme can be repaired so as to resist modest quantum attacks.
OT (Oblivious transfer) is a fundamental primitive in cryptography. But it is well known that in quantum cryptography, unconditionally secure OT is impossible. A variant of OT, i.e. randomized OT, is presented. We then show how to realize this variant in quantum cryptography with some security relaxations, which is inevitable because of the well-known impossible result in quantum cryptography. We also present a new secure computational model, namely HRC (Hacker-Resistant Computation) model. Since on today’s Internet there are more and more hackers and increased cyber threat, knowing how to protect the information and privacy stored on our computer and on cloud servers is very important, even when the computer or server has been breached by hackers. Finally, some interesting applications of the randomized OT variant to HRC are discussed.
Oblivious transfer (OT) is one of the most fundamental primitives in cryptography and is widely used in protocols for secure two-party and multi-party computation. As secure com-putation becomes more practical, the need for practical large scale oblivious transfer protocols is becoming more evident. Oblivious transfer extensions are protocols that enable a relatively small number of “base-OTs ” to be utilized to compute a very large number of OTs at low cost. In the semi-honest setting, Ishai et al. (CRYPTO 2003) presented an OT extension protocol for which the cost of each OT (beyond the base-OTs) is just a few hash function operations. In the malicious setting, Nielsen et al. (CRYPTO 2012) presented an efficient OT extension protocol for the setting of active adversaries, that is secure in the random oracle model. In this work, we present an OT extension protocol for the setting of malicious adversaries that is more efficient and uses less communication than previous works. In addition, our protocol can be proven secure in both the random oracle model, and in the standard model with a type of correlation robustness. Given the importance of OT in many secure computation protocols, increasing the efficiency of OT extensions is another important step forward to making secure
Oblivious Transfer (OT) is a fundamental cryptographic protocol with applications in secure Multi-Party Computation, Federated Learning, and Private Set Intersection. With the advent of quantum computing, it is crucial to develop unconditionally secure core primitives like OT to ensure their continued security in the post-quantum era. Despite over four decades since OT's introduction, the literature has predominantly relied on computational assumptions, except in cases using unconventional methods like noisy channels or a fully trusted party. Introducing "Supersonic OT", a highly efficient and unconditionally secure OT scheme that avoids public-key-based primitives, we offer an alternative to traditional approaches. Supersonic OT enables a receiver to obtain a response of size O(1). Its simple (yet non-trivial) design facilitates easy security analysis and implementation. The protocol employs a basic secret-sharing scheme, controlled swaps, the one-time pad, and a third-party helper who may be corrupted by a semi-honest adversary. Our implementation and runtime analysis indicate that a single instance of Supersonic OT completes in 0.35 milliseconds, making it up to 2000 times faster than the state-of-the-art base OT.
Oblivious transfer (OT) is one of the keystones of secure multi-party computation. It is generally believed that unconditionally secure OT is impossible. In this article, we propose a practical and secure quantum all-or-nothing oblivious transfer protocol based on the quantum one-way function. The protocol is built upon a quantum public-key encryption construction, and its security relies on the no-cloning theorem and no-communication theorem. Practical security is reflected in limitations on non-demolition measurements.
Oblivious transfer, a central functionality in modern cryptography, allows a party to send two one-bit messages to another who can choose one of them to read, remaining ignorant about the other, whereas the sender does not learn the receiver's choice. Oblivious transfer the security of which is information-theoretic for both parties is known impossible to achieve from scratch. The joint behavior of certain bi-partite quantum states is non-local, i.e., cannot be explained by shared classical information. In order to better understand such behavior, which is classically explainable only by communication, but does not allow for it, Popescu and Rohrlich have described a "non-locality machine": Two parties both input a bit, and both get a random output bit the XOR of which is the AND of the input bits. We show a close connection, in a cryptographic sense, between OT and the "PR primitive." More specifically, unconditional OT can be achieved from a single realization of PR, and vice versa. Our reductions, which are single-copy, information-theoretic, and perfect, also lead to a simple and optimal protocol allowing for inverting the direction of OT
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.