Designing privacy preserving cryptographic protocols

Keith B. Frikken, Mikhail J. Atallah

Thomas Schneider, Amos Treiber

Privacy-preserving scalar product (PPSP) protocols are an important building block for secure computation tasks in various applications. Lu et al. (TPDS'13) introduced a PPSP protocol that does not rely on cryptographic assumptions and that is used in a wide range of publications to date. In this comment paper, we show that Lu et al.'s protocol is insecure and should not be used. We describe specific attacks against it and, using impossibility results of Impagliazzo and Rudich (STOC'89), show that it is inherently insecure and cannot be fixed without relying on at least some cryptographic assumptions.

Bartosz Przydatek

Ron Steinfeld

Lattice-based cryptography is one of the most promising candidates for designing post-quantum cryptographic algorithms that resist emerging quantum computing attacks. The recent NIST PQC standardization process is nearing its completion, with practical lattice-based algorithms for basic cryptographic functionalities (namely digital signature and public-key encryption) selected for standardization in the near future. However, practical lattice-based solutions for more advanced privacy-preserving protocols, in particular, Zero-Knowledge Proofs (ZKPs), have only emerged recently and are an active area of research. We discuss some recent developments in design and analysis of practical lattice-based post-quantum ZKPs and their applications. In particular, we review some challenges that arise in designing ZKPs in the lattice setting and some recent progress on efficient lattice-based Schnorr-like proofs for important relations, such as binary/range proofs, one-out-of-many proofs and rounding proofs [1, 2, 4]. We discuss applications and optimization of such proof systems as building blocks for practical advanced cryptographic protocols such as ring signatures and balance proofs for privacy-preserving cryptocurrency payment protocols [2, 3]. We also discuss our recent work on succinct designated-verifier ZKPs (DV-ZKSNARKS) for verifying correctness of general delegated computations [5].

Jincheng Zhang

This paper presents a novel approach to achieving secure differential privacy utilizing the unique properties of quantum entanglement. We propose a quantum key distribution (QKD) protocol where the inherent noise within the entangled state itself serves as a mechanism for guaranteeing differential privacy. Unlike traditional cryptographic methods that rely on computational assumptions, our approach leverages the fundamental randomness of quantum mechanics. The core idea is that the statistical fluctuations observed in the measurement of entangled pairs provide a natural perturbation, effectively masking individual data points while preserving the overall statistical properties of the dataset. The protocol is designed to be provably secure, offering a stronger security guarantee than classical differential privacy techniques. We formalize this approach with mathematical equations, outlining the key components and their impact on privacy. The research contributes a new paradigm for privacy preservation, potentially offering a path towards highly secure and robust data analysis in the quantum era.

Ronald Cramer