Blockchain technology emphasizes trust and collaboration through distributed networks and is deemed to contribute to building information modeling (BIM) based construction collaboration and management. However, the open nature of blockchain introduces severe cybersecurity attacks that undermine the trustworthiness of construction management. One salient point is identity authentication for security BIM data access in the blockchain environment. The traditional public-private key or password authenticate methods are vulnerable to malicious theft. Zero-Knowledge Proof (ZKP) is an emerging, password-free method for authenticating identities. It allows one party to prove the truth or falsity of a statement to another party without revealing any meaningful information to the counterpart. Therefore, this study proposes a preliminary user authentication protocol based on the non-interactive ZKP protocol, specifically the zk-SNARK protocol, for adaptive authentication of blockchain BIM. The adaptive authentication recognizes a random subset of on-chain historical BIM operation records to prove the identity according to the protocol. Without revealing any meaningful knowledge to the authentication system, this adaptive data access control prevents password attacks using the BIM records on-chain. Finally, the proposed protocol is deployed on the test blockchain and implemented in a preliminary case study to illustrate the feasibility and effectiveness of the proposed method. The main contribution of this paper is twofold. Firstly, the theoretical contribution is proposing a novel zk-SARKs-based identity authentication protocol that utilizes the on-chain BIM operation records. Secondly, the practical contribution relies on presenting a ZoKrates-based workflow of generating proofs, creating smart contracts, and deploying on the blockchain for verification
We present a general purpose, privacy-preserving framework for verifying user attributes. The framework is designed for users (e.g., a job candidate) to allow a challenger (e.g., a prospective employer) to verify whether the usermeets a particular requirement (e.g., does the candidate hold a valid driving license?), without leaking any other information about the user. Importantly, the user is an active part of the challenge-verification process, which ensures that challenges cannot be made without the user’s full knowledge and participation. The framework is decentralized and requires a public blockchain. A smart contract is used to manage the challenge-verification process, and zero-knowledge proofs are used to verify challenges in a privacy-preserving manner. We implement a simplified version of the framework using smart contracts deployed on the Ethereum blockchain, and we simulate some simple use cases. All simulation code is available open-source (https://github.com/lifeisbeer/BlockVerify).
Carmit Hazay, Muthuramakrishnan Venkitasubramaniam, Mor Weiss
Abstract Distributed zero-knowledge (dZK) proofs, recently introduced by Boneh et al. (CRYPTO‘19), allow a prover $$\mathcal{P}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>P</mml:mi> </mml:math> to prove NP statements on an input x , which is distributed between k verifiers $$\mathcal{V}_1,\ldots ,\mathcal{V}_k$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>V</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mo>,</mml:mo> <mml:mo>…</mml:mo> <mml:mo>,</mml:mo> <mml:msub> <mml:mi>V</mml:mi> <mml:mi>k</mml:mi> </mml:msub> </mml:mrow> </mml:math> , where each $$\mathcal{V}_i$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>V</mml:mi> <mml:mi>i</mml:mi> </mml:msub> </mml:math> holds only a piece of x . As in standard ZK proofs, dZK proofs guarantee Completeness when all parties are honest; Soundness against a malicious prover colluding with t verifiers; and Zero Knowledge against a subset of t malicious verifiers, in the sense that they learn nothing about the NP witness and the input pieces of the honest verifiers. Unfortunately, dZK proofs provide no correctness guarantee for an honest prover against a subset of maliciously corrupted verifiers. In particular, such verifiers might be able to “frame” the prover, causing honest verifiers to reject a true claim. This is a significant limitation, since such scenarios arise naturally in dZK applications, e.g., for proving honest behavior, and such attacks are indeed possible in existing dZKs (Boneh et al., CRYPTO‘19). We put forth and study the notion of strong completeness for dZKs, guaranteeing that true claims are accepted even when t verifiers are maliciously corrupted. We then design strongly-complete dZK proofs in the honest-majority setting using the “MPC-in-the-head” paradigm of Ishai et al. (STOC‘07), providing a novel analysis that exploits the unique properties of the distributed setting. To demonstrate the usefulness of strong completeness, we present several applications in which it is instrumental in obtaining security. First, we construct a certifiable version of Verifiable Secret Sharing (VSS), which is a VSS in which the dealer additionally proves that the shared secret satisfies a given NP relation. Our construction withstands a constant fraction of corruptions, whereas a previous construction of Ishai et al. (TCC‘14) required $$k={\textsf{poly}}\left( t\right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>k</mml:mi> <mml:mo>=</mml:mo> <mml:mi>poly</mml:mi> <mml:mfenced> <mml:mi>t</mml:mi> </mml:mfenced> </mml:mrow> </mml:math> . We also design a reusable version of certifiable VSS that we introduce, in which the dealer can prove an unlimited number of predicates on the same shared secret. Finally, we extend a compiler of Boneh et al. (CRYPTO‘19), who used dZKs to transform a class of “natural” semi-honest protocols in the honest-majority setting into maliciously secure ones with abort. Our compiler uses strongly-complete dZKs to obtain identifiable abort.
This paper explores the feasibility of a fiat stablecoin that provides similar privacy guarantees to cash. We show how individuals in a stablecoin privacy pool can exchange small amounts of value within pre-assigned limits outside the view of third parties, such as banks, central banks, crypto exchanges, regulators, or other parties, in a regulatorily compliant way. High privacy guarantees and compliance with limits are ensured in a trustless way via the use of cryptographic zero-knowledge proofs.
This paper delves into two legal models for zero-knowledge proof protocols in the context of the eIDAS 2.0 Regulation: a trust service or a software product. The ARIES: reliAble euRopean Identity EcoSystem EU project highlighted the need for a legal framework for stakeholders to accept proof of the existence of user data with legal certainty, while Hyperledger Indy shows that ZKP solutions are currently commercialized, stressing deficiencies in the eIDAS 2.0. An overview of ZKP applied to identity, its relationship to the European Digital Identity Wallet and the electronic attestations of attributes, both introduced by the eIDAS 2.0, and Self-Sovereign Identity systems, leads to the central question of proof of the existence of user-held data as a trust service or as a software product and its data privacy implications for each approach. Finally, we outline a possible solution based on the product approach for future work. Our findings reveal that ZKP technology must have legal value and a presumption system to be effective. However, the path we take could lead us either to develop a system of surveillance and control in electronic environments or to build an environment where we share not the data itself but proof of its existence.
Ye Tao, Ehsan Javanmardi, Pengfei Lin, Jin Nakazato · 7 authors
Cooperative perception is crucial for connected automated vehicles in intelligent transportation systems (ITSs); however, ensuring the authenticity of perception data remains a challenge as the vehicles cannot verify events that they do not witness independently. Various studies have been conducted on establishing the authenticity of data, such as trust-based statistical methods and plausibility-based methods. However, these methods are limited as they require prior knowledge such as previous sender behaviors or predefined rules to evaluate the authenticity. To overcome this limitation, this study proposes a novel approach called zero-knowledge Proof of Traffic (zk-PoT), which involves generating cryptographic proofs to the traffic observations. Multiple independent proofs regarding the same vehicle can be deterministically cross-verified by any receivers without relying on ground truth, probabilistic, or plausibility evaluations. Additionally, no private information is compromised during the entire procedure. A full on-board unit software stack that reflects the behavior of zk-PoT is implemented within a specifically designed simulator called Flowsim. A comprehensive experimental analysis is then conducted using synthesized city-scale simulations, which demonstrates that zk-PoT’s cross-verification ratio ranges between 80 % to 96 %, and 90 % of the verification is achieved in 5 s, with a protocol overhead of approximately 25 %. Furthermore, the analyses of various attacks indicate that most of the attacks could be prevented, and some, such as collusion attacks, can be mitigated. The proposed approach can be incorporated into existing works, including the European Telecommunications Standards Institute (ETSI) and the International Organization for Standardization (ISO) ITS standards, without disrupting the backward compatibility.
Open access
3 source records
Privacy-Preserving Technologies in Data
Vehicular Ad Hoc Networks (VANETs)
Advanced Steganography and Watermarking Techniques
Carsten Baum, Chiang, James Hsin-yu, Bernardo David, Tore Kasper Frederiksen
Recent years have seen the emergence of practical advanced cryptographic tools that not only protect data privacy and authenticity, but also allow for jointly processing data from different institutions without sacrificing privacy. The ability to do so has enabled implementations of a number of traditional and decentralized financial applications that would have required sacrificing privacy or trusting a third party. The main catalyst of this revolution was the advent of decentralized cryptocurrencies that use public ledgers to register financial transactions, which must be verifiable by any third party, while keeping sensitive data private. Zero Knowledge (ZK) proofs rose to prominence as a solution to this challenge, allowing for the owner of sensitive data (e.g. the identities of users involved in an operation) to convince a third party verifier that a certain operation has been correctly executed without revealing said data. It quickly became clear that performing arbitrary computation on private data from multiple sources by means of secure Multiparty Computation (MPC) and related techniques allows for more powerful financial applications, also in traditional finance. \nIn this SoK, we categorize the main traditional and decentralized financial applications that can benefit from state-of-the-art Privacy-Enhancing Technologies (PETs) and identify design patterns commonly used when applying PETs in the context of these applications. In particular, we consider the following classes of applications: 1. Identity Management, KYC & AML; 2. Markets & Settlement; 3. Legal; and 4. Digital Asset Custody. We examine how ZK proofs, MPC and related PETs have been used to tackle the main security challenges in each of these applications. Moreover, we provide an assessment of the technological readiness of each PET in the context of different financial applications according to the availability of: theoretical feasibility results, preliminary benchmarks (in scientific papers) or benchmarks achieving real-world performance (in commercially deployed solutions). Finally, we propose future applications of PETs as Fintech solutions to currently unsolved issues. While we systematize financial applications of PETs at large, we focus mainly on those applications that require privacy preserving computation on data from multiple parties.
We provide a generic construction to turn any classical Zero-Knowledge (ZK) protocol into a composable (quantum) oblivious transfer (OT) protocol, mostly lifting the round-complexity properties and security guarantees (plain-model/statistical security/unstructured functions...) of the ZK protocol to the resulting OT protocol. Such a construction is unlikely to exist classically as Cryptomania is believed to be different from Minicrypt. In particular, by instantiating our construction using Non-Interactive ZK (NIZK), we provide the first round-optimal (2-message) quantum OT protocol secure in the random oracle model, and round-optimal extensions to string and k-out-of-n OT. At the heart of our construction lies a new method that allows us to prove properties on a received quantum state without revealing additional information on it, even in a non-interactive way, without public-key primitives, and/or with statistical guarantees when using an appropriate classical ZK protocol. We can notably prove that a state has been partially measured (with arbitrary constraints on the set of measured qubits), without revealing any additional information on this set. This notion can be seen as an analog of ZK to quantum states, and we expect it to be of independent interest as it extends complexity theory to quantum languages, as illustrated by the two new complexity classes we introduce, ZKstatesQIP and ZKstatesQMA.
Ball sort puzzle is a popular logic puzzle consisting of several bins containing balls of multiple colors. Each bin works like a stack; a ball has to follow the last-in first-out order. The player has to sort the balls by color such that each bin contains only balls of a single color. In this paper, we propose a physical zero-knowledge proof protocol for the ball sort puzzle using a deck of playing cards, which enables a prover to physically show that he/she knows a solution with $t$ moves of the ball sort puzzle without revealing it. Our protocol is the first zero-knowledge proof protocol for an interactive puzzle involving moving objects.
Aleksander Berentsen, Jeremias Lenzi, Remo Nyffenegger
With a zero-knowledge proof (ZKP), a party can prove that a statement is true without revealing any information except for whether it is indeed true or not. The obvious benefit is privacy since the prover does not need to reveal any additional information, and the second benefit is that it can significantly reduce the cost of verifying the correctness of a statement.
Systems for generating and managing digital identities are in the process of being transformed to improve data sharing security and increase decentralization. Addressing both issues, a theoretical solution to create and manage Self-Sovereign Identities (SSI) is proposed using two Zero-Knowledge Proof (ZKP) protocols based on the discrete logarithm difficulty. Automorphism group properties are introduced to link several identities, their identifiers and attributes to produce a proof. The proposed SSI protocol does not encounter the problem of reusing the same secret key as in the case of the initial ZKP Schnorr protocol. The designed protocol ensures minimal disclosure of information to a single trusted third party. In addition, it allows zero disclosure of information to service providers requiring proof of authentication or identification. Such a SSI protocol is compliant with Electronic IDentification And Trust Services (eIDAS) as well as General Data Protection Regulation (GDPR) regulations.
Zero-Knowledge Proof (ZKP) is a useful tools for proving that a prover possesses a secret without revealing it to the verifier. Designated Verifier Proof (DVP) is a special type of ZKP that adds the ability to restrict the identity of verifiers so that only pre-determined authorized verifiers can verify. However, DVP and other similar schemes do not work if the verifier provides some additional information to indicate the provenance of the proof. Since this information may be stored on the blockchain, the proof can be accepted by third parties even if the verifier is willing to protect the privacy of the prover. In this paper, we propose the concept of Blockchain Designated Verifier Proof (BDVP), and design a BDVP scheme suitable for blockchain applications. The key technique behind our BDVP scheme is that the verifier can forge a fake secret to simulate the proof. Therefore, a third party cannot determine whether the prover possesses the secret. This enables the verifier to protect the privacy of the prover, which is required by law or regulation. We also address the quantum attack problem and propose a post-quantum solution. We evaluate and compare the performances of the proposed protocol with other related protocols.
Cryptography is one of the most important approaches to keep digital communication in lock and key and therefore guarantees the privacy, integrity and authenticity of the data by means of complex coding. Cryptographic techniques have arisen centuries ago and the old techniques have continued to evolve as today’s challenges are cloud computing, data storage and retrieval as well as authenticated users. With the widespread spread of cloud environments, trust-enabling systems with cutting-edge technologies such as Zero Knowledge Proofs and blockchain emerged to increase privacy and security. By examining the notion of trust localization, this study draws attention to a use of Gateways as access control points to sensitive information reducing the dependence on the central cloud infrastructures. Additionally, source authentication and authorization provided by Acaras and PKI is studied regarding their integration and effectiveness. The research examines the current challenges in cryptographic security and current findings of cryptographic security and investigates what the future of cryptographic security to build trust and security in modern digital systems..