The ISC International Journal of Information Security

Abstract Oblivious Transfer (OT) is one of the fundamental building blocks in cryptography that enables various privacy-preserving applications. Constructing efficient OT schemes has been an active research area. This paper presents three efficient two-round pairing-free k-out-of-n oblivious transfer protocols with standard security. Our constructions follow the minimal communication pattern: the receiver sends k messages to the sender, who responds with n+k messages, achieving the lowest data transmission among pairing-free k-out-of-n OT schemes. Furthermore, our protocols support adaptivity and enable the sender to encrypt the n messages offline, independent of the receiver’s variables, offering significant performance advantages in one-sender-multiple-receiver scenarios. We provide security proofs under the Computational Diffie-Hellman (CDH) and RSA assumptions, without relying on the Random Oracle Model. Our protocols combine minimal communication rounds, adaptivity, offline encryption capability, and provable security, making them well-suited for privacy-preserving applications requiring efficient oblivious transfer. 

Abstract Smart grids using information technology (IT) and communication networks control smart home appliances to reduce costs and increase reliability and transparency. Preserving the privacy of the user data is one of the biggest challenges in smart grid research; by disclosing user-related data, an internal or external adversary can understand the habits and behavior of the users. A solution to address this challenge is, however, a data aggregation mechanism in which the aggregated data of all of the users in a residential area. The security and efficiency of the data aggregation approach are important. The drawback of the previous works is leaking fine-grained user data or the high computation and communication overhead. In this paper, we present an efficient privacy-preserving data-aggregation protocol, called PPDA, based on the Elliptic Curve Cryptography (ECC) and Anonymous Veto network protocol. The PPDA protocol aggregates metering data efficiently and securely so that it becomes applicable for resource-constraint metering devices. We also present an improved multi-cycle proposal of PPDA, called MC-PPDA. In the improved approach, the system initialization step runs only at the first cycle of the protocol which increases the efficiency of the protocol. Evaluation results show that the proposed approaches preserve the privacy of the fine-grained user data against an internal and external adversary; the improved multi-cycle approach is also secure against collusion. Compared to the previous approaches, the proposed approaches incur less computation and communication overhead.