Universal composability (UC) is a primary security flavor for designing oblivious transfer (OT) due to its advantage of arbitrary composition. However, the study of UC‐secure OT over lattices is still far behind compared with constructions over prequantum assumptions. Relying on the learning with errors (LWE) assumption, Quach proposes a dual‐mode encryption scheme (SCN’20) for deriving a two‐round OT whose security is provably UC‐secure in the common reference string (CRS) model. Due to its use of a randomized rounding function proposed by Benhamouda et al. (PKC’18), this OT can only be limited to transmitting single‐bit messages. Therefore, conducting trivial repetitions of Quach’s OT when transmitting multibit strings would be very costly. In this work, we put forward a modified dual‐mode encryption cryptosystem under the decisional LWE assumption, from which we can derive a UC‐secure string OT with both full‐fledged dual‐mode security and better efficiency on transmitting strings. The key technique we adopt is a key reconciliation scheme proposed by Jiang et al. (PKC’20), which is utilized to extend the single‐bit symmetric encryption key (produced by the aforementioned rounding function) to a multibit case. Through a comprehensive performance analysis, we demonstrate that our proposal can indeed strike a balance between security and efficiency.
Universal composability (UC) is a primary security flavor for designing oblivious transfer (OT) due to its advantage of arbitrary composition. However, the study of UC‐secure OT over lattices is still far behind compared with constructions over prequantum assumptions. Relying on the learning with errors (LWE) assumption, Quach proposes a dual‐mode encryption scheme (SCN’20) for deriving a two‐round OT whose security is provably UC‐secure in the common reference string (CRS) model. Due to its use of a randomized rounding function proposed by Benhamouda et al. (PKC’18), this OT can only be limited to transmitting single‐bit messages. Therefore, conducting trivial repetitions of Quach’s OT when transmitting multibit strings would be very costly. In this work, we put forward a modified dual‐mode encryption cryptosystem under the decisional LWE assumption, from which we can derive a UC‐secure string OT with both full‐fledged dual‐mode security and better efficiency on transmitting strings. The key technique we adopt is a key reconciliation scheme proposed by Jiang et al. (PKC’20), which is utilized to extend the single‐bit symmetric encryption key (produced by the aforementioned rounding function) to a multibit case. Through a comprehensive performance analysis, we demonstrate that our proposal can indeed strike a balance between security and efficiency.
Authenticationis the first defence line to prevent malicious entities to accesssmart mobile devices(or SMD). Essentially, there exist many available cryptographic primitives to design authentication protocols.Oblivious transfer() protocol is one of the important cryptographic primitives to design authentication protocols. The first lattice‐based framework under universal composability (UC) model was designed by dual mode encryption and promoted us to find an alternative efficient scheme. We note that “lossy encryption” scheme is an extension of the dual mode encryption and can be used to design UC‐secure protocol, but the investigations of via lossy encryption over the lattice are absent. Hence, in order to obtain an efficient authentication protocol by improving the performance of the UC‐secure protocol, in this paper, we first design a multibit lossy encryption under the decisional learning with errors () assumption and then design a new variant of UC‐secure protocol for authenticated protocol via lossy encryption scheme. Additionally, our protocol is secure against semihonest (static) adversaries in the common reference string (CRS) model and within the UC framework.
Non-committing encryption achieved only semantic security,in contrast,applications often require security against chosen ciphertext attacks.A main ingredient in the previous adaptive universally composable(UC)oblivious transfer protocols are non-committing encryptions.the previous proposals are not UC secure against adaptive adversaries in the so-called non-erase model.A new UC secure oblivious transfer protocols were proposed and schemes utilize two primitives of the verifiably smooth projective hashing and deniable encryption as constructed by.the double trapdoor decryption mechanism based on trapdoor commitment.Our construction is based on the decisional composite residuosity in common reference string (CRS) model.We constructed a two-message(1-round) string oblivious transfer protocol,which improves computational efficient that supports message spaces of size exponential and save O(n)-1 rounds communications efficient than bit-OT protocols.
We propose postquantum universal composable (UC) cut-and-choose oblivious transfer (CCOT) protocol under the malicious adversary model. In secure two-party computation, we construct s copies’ garbled circuits, including half check circuit and half evaluation circuit. The sender can transfer the key to the receiver by CCOT protocol. Compared to PVW-OT [6] framework, we invoke WQ-OT [35] framework with reusability of common random string ( crs ) and better security. Relying on LWE’s assumption and the property of the Rounding function, we construct an UC-CCOT protocol, which can resist quantum attack in secure two-party computation.
Cloud computing is a promising paradigm to provide flexible and reliable services. Nevertheless, concern and anxiety about data security and tenants’ privacy are still a major barrier for the popularity of cloud computing. Oblivious transfer (OT) is a cryptographic primitive that enables a client to selectively retrieve data in a privacy-preserving manner. It can be used to construct high-level protocols enabling applications in the cloud-computing paradigm. Technically, it has been proven that OT protocols can be constructed using a CPA-secure public-key encryption scheme. Along these lines, Peikert et al. formulated a dual-mode cryptosystem on which they constructed a single-bit OT scheme. Obviously, it has deficiencies in performance, which makes it unqualified for use in cloud-computing scenarios. This paper aims at providing an efficient multi-bit OT scheme for secure cloud applications. We first propose a multi-bit dual-mode cryptosystem based on the learning with errors (LWE) problem. Based on this multi-bit dual-mode cryptosystem, we construct a multi-bit OT. We present details of the OT construction together with security analysis of our scheme, and finally provide an example of how it can be used in specific application scenarios.
Oblivious Transfer (OT) is a fundamental cryptographic protocol that finds a number of applications, in particular, as an essential building block for two-party and multi-party computation. We construct a round-optimal (2 rounds) universally composable (UC) protocol for oblivious transfer secure against active adaptive adversaries from any OW-CPA secure public-key encryption scheme with certain properties in the random oracle model (ROM). In terms of computation, our protocol only requires the generation of a public/secret-key pair, two encryption operations and one decryption operation, apart from a few calls to the random oracle. In~terms of communication, our protocol only requires the transfer of one public-key, two ciphertexts, and three binary strings of roughly the same size as the message. Next, we show how to instantiate our construction under the low noise LPN, McEliece, QC-MDPC, LWE, and CDH assumptions. Our instantiations based on the low noise LPN, McEliece, and QC-MDPC assumptions are the first UC-secure OT protocols based on coding assumptions to achieve: 1) adaptive security, 2) optimal round complexity, 3) low communication and computational complexities. Previous results in this setting only achieved static security and used costly cut-and-choose techniques.Our instantiation based on CDH achieves adaptive security at the small cost of communicating only two more group elements as compared to the gap-DH based Simplest OT protocol of Chou and Orlandi (Latincrypt 15), which only achieves static security in the ROM.
We present a general framework for efficient, universally composable oblivious transfer (OT) protocols in which a single, global, common reference string (CRS) can be used for multiple invocations of oblivious transfer by arbitrary pairs of parties. In addition: • Our framework is round-efficient. E.g., under the DLIN or SXDH assumptions we achieve round-optimal protocols with static security, or 3-round protocols with adaptive security (assuming erasure). • Our resulting protocols are more efficient than any known previously, and in particular yield protocols for string OT using O(1) exponentiations and communicating O(1) group elements. Our result improves on that of Peikert et al. (Crypto 2008), which uses a CRS whose length depends on the number of parties in the network and achieves only static security. Compared to Garay et al. (Crypto 2009), we achieve adaptive security with better round complexity and efficiency. ∗Columbia University. Email: sgchoi@cs.columbia.edu. Portions of this work were done at the University of Maryland. This work was supported in part by the Intelligence Advanced Research Project Activity (IARPA) via DoI/NBC contract Number D11PC20194. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of IARPA, DoI/NBC, or the U.S. Government. †Dept. of Computer Science, University of Maryland. Email: jkatz@cs.umd.edu. This work is supported in part by DARPA and by NSF awards #0447075, #1111599, and #1223623. ‡George Washington University. Email: hoeteck@alum.mit.edu. Supported by NSF CAREER award #1237429. §Dept. of Computer Science, Virginia Commonwealth University. Email: hszhou@vcu.edu. Work supported in part by an NSF CI postdoctoral fellowship, and done while at University of Maryland.