Blockchain Papers

Kalikinkar Mandal, Guang Gong

No abstract is available for this record.

Jiamin Cui, Kai Hu, Meiqin Wang, Puwen Wei

No abstract is available for this record.

Guanxiong Ha, Chunfu Jia, Xiaowei Ge, Jiawei Yuan · 6 authors

No abstract is available for this record.

Xiao Yang, Mengling Liu, Man Ho Au, Xiapu Luo · 5 authors

Verifiably encrypted signature (VES) allows a signer to encrypt a signature under the public key of a trusted third party (aka adjudicator) in a verifiable manner. Recently, Yanget al.proposed a practical verifiably encrypted signature scheme for ECDSA and initiated the study of escrow protocol for Bitcoin via VES. This paper generalizes and improves the VES scheme of Yanget al., such that it covers a family of signatures with similar structures, including ECDSA, Schnorr and their variants. Our construction is very efficient: comparing with Yanget al.’s construction, the size of the resulting VES (for ECDSA) is reduced by more than 25 times. The only caveat is that the adjudicator is required to store a look-up table of size around 270MB. Our scheme naturally gives rise to escrow protocols for mainstream cryptocurrencies that employ ECDSA-like signatures to authorise transaction, including Bitcoin, Ethereum, Cardano, Chainlink, etc.

Kristian Gjøsteen, Thomas Haines, Johannes Müller, Peter B. Rønne · 5 authors

No abstract is available for this record.

Giuseppe Persiano, Duong Hieu Phan, Moti Yung

No abstract is available for this record.

Léo Robert, Daiki Miyahara, Pascal Lafourcade, Takaaki Mizuki

No abstract is available for this record.

Handong Zhang, Puwen Wei, Haiyang Xue, Yi Deng · 7 authors

No abstract is available for this record.

Elvira Albert, Marta Bellés-Muñoz, Miguel Isabel, Clara Rodríguez-Núñez · 5 authors

Abstract The most widely used Zero-Knowledge (ZK) protocols require provers to prove they know a solution to a computational problem expressed as a Rank-1 Constraint System (R1CS). An R1CS is essentially a system of non-linear arithmetic constraints over a set of signals, whose security level depends on its non-linear part only, as the linear (additive) constraints can be easily solved by an attacker. Distilling the essential constraints from an R1CS by removing the part that does not contribute to its security is important, not only to reduce costs (time and space) of producing the ZK proofs, but also to reveal to cryptographic programmers the real hardness of their proofs. In this paper, we formulate the problem of distilling constraints from an R1CS as the (hard) problem of simplifying constraints in the realm of non-linearity. To the best of our knowledge, it is the first time that constraint-based techniques developed in the context of formal methods are applied to the challenging problem of analysing and optimizing ZK protocols.

Christian Badertscher, Peter Gaži, Iñigo Querejeta-Azurmendi, Alexander Russell

No abstract is available for this record.

Jonathan Bootle, Alessandro Chiesa, Siqi Liu

No abstract is available for this record.

Xavier Arnal, Abraham Cano, Tamara Finogina, Javier Herranz

No abstract is available for this record.

Tiancheng Xie, Yupeng Zhang, Dawn Song

No abstract is available for this record.

Suthee Ruangwises, Toshiya Itoh

Makaro is a logic puzzle with an objective to fill numbers into a rectangular grid to satisfy certain conditions. In 2018, Bultel et al. developed a physical zero-knowledge proof (ZKP) protocol for Makaro using a deck of cards, which allows a prover to physically convince a verifier that he/she knows a solution of the puzzle without revealing it. However, their protocol requires several identical copies of some cards, making it impractical as a deck of playing cards found in everyday life typically consists of all different cards. In this paper, we propose a new ZKP protocol for Makaro that can be implemented using a standard deck (a deck consisting of all different cards). Our protocol also uses asymptotically less cards than the protocol of Bultel et al. Most importantly, we develop a general method to encode a number with a sequence of all different cards. This allows us to securely compute several numerical functions using a standard deck, such as verifying that two given numbers are different and verifying that a number is the largest one among the given numbers.

Lu Lin, Baocheng Wang

More and more countries are exploring smart city related smart facilities to benefit the society. Remote access and control of IOT smart devices is convenient, but there are also some risks. Smart devices may be attacked by criminals who will do serious harm to the production environment. It is particularly important to design a safe and efficient secure communication scheme. Most existing solutions to this problem are usually based on single server architecture, which has some problems in security and efficiency. Aiming at the problem that authentication and key agreement in smart water conservancy are vulnerable to SPOF and DDOS attacks, this paper proposes an authentication key agreement technology based on blockchain. In key agreement, the identity of smart devices can not be tampered with, which can effectively resist man in the middle attack. In the process of protocol execution, the nodes of smart devices are light nodes. The process of key agreement is carried out in the smart contract, which reduces the computational complexity and improves the operation efficiency. This paper also analyzes the security of the scheme.

Nguyen Thoi Minh Quan

What is the funniest number in cryptography (Episode 2)? 0 [1]. The reason is that $\forall x, x \cdot 0 = 0$, i.e., the equation is satisfied no matter what $x$ is. We'll use zero to attack zero-knowledge proof (ZKP). In particular, we'll discuss a critical issue in a cutting-edge ZKP PLONK [2] C++ implementation which allows an attacker to create a forged proof that all verifiers will accept. We'll show how theory guides the attack's direction. In practice, the attack works like a charm and we'll show how the attack falls through a chain of perfectly aligned software cracks. In the same codebase, there is an independent critical ECDSA bug where (r, s) = (0, 0) is a valid signature for arbitrary keys and messages, but we won't discuss it further because it's a known ECDSA attack vector in the Google Wycheproof cryptanalysis project [3] that I worked on a few years ago. All bugs have been responsibly disclosed through the vendor's bug bounty program with total reward $\sim \$15,000$ (thank you).

Rashmi Agrawal, Ji Yang, Haris Javaid

As enterprises embrace blockchain technology, many real-world applications have been developed and deployed using permissioned blockchain platforms (access to network is controlled and given to only nodes with known identities). Such blockchain platforms heavily depend on cryptography to provide a layer of trust within the network, thus verification of cryptographic signatures often becomes the bottleneck. The Elliptic Curve Digital Signature Algorithm (ECDSA) is the most commonly used cryptographic scheme in permissioned blockchains. In this paper, we propose an efficient implementation of ECDSA signature verification on an FPGA, in order to improve the performance of permissioned blockchains that aim to use FPGA-based hardware accelerators. We propose several optimizations for modular arithmetic (e.g., custom multipliers and fast modular reduction) and point arithmetic (e.g., reduced number of point double and addition operations, and optimal width NAF representation). Based on these optimized modular and point arithmetic modules, we propose an ECDSA verification engine that can be used by any application for fast verification of ECDSA signatures. We further optimize our ECDSA verification engine for Hyperledger Fabric (one of the most widely used permissioned blockchain platforms) by moving carefully selected operations to a precomputation block, thus simplifying the critical path of ECDSA signature verification. From our implementation on Xilinx Alveo U250 accelerator board with target frequency of 250MHz, our ECDSA verification engine can perform a single verification in $760μs$ resulting in a throughput of 1,315 verifications per second, which is ~2.5x faster than state-of-the-art FPGA-based implementations. Our Hyperledger Fabric-specific ECDSA engine can perform a single verification in $368μs$ with a throughput of 2,717 verifications per second.

Marta Bellés-Muñoz, Barry Whitehat, Jordi Baylina, Vanesa Daza · 5 authors

Circuit-based zero-knowledge proofs have arose as a solution to the implementation of privacy in blockchain applications, and to current scalability problems that blockchains suffer from. The most efficient circuit-based zero-knowledge proofs use a pairing-friendly elliptic curve to generate and validate proofs. In particular, the circuits are built connecting wires that carry elements from a large prime field, whose order is determined by the number of elements of the pairing-friendly elliptic curve. In this context, it is important to generate an inner curve using this field, because it allows to create circuits that can verify public-key cryptography primitives, such as digital signatures and encryption schemes. To this purpose, in this article, we present a deterministic algorithm for generating twisted Edwards elliptic curves defined over a given prime field. We also provide an algorithm for checking the resilience of this type of curve against most common security attacks. Additionally, we use our algorithms to generate Baby Jubjub, a curve that can be used to implement elliptic-curve cryptography in circuits that can be validated in the Ethereum blockchain.

José Bacelar Almeida, Manuel Barbosa, Manuel L. Correia, Karim Eldefrawy · 7 authors

MPC-in-the-Head (MitH) is a general framework that enables constructing efficient zero-knowledge (ZK) protocols for NP relations from secure multiparty computation (MPC) protocols. In this paper we present the first machine-checked implementations of MitH.

Gholamreza Ramezan, Amr Abdelnasser, Bingyang Liu, Weiyu Jiang · 5 authors

5G has Introduced the primary and secondary authentication procedures to authenticate the user equipment requesting access to mobile network operators (MNOs) and service providers (SPs) data networks, respectively. However, the possibility of running distributed denial of service (DDoS) attacks on the MNO 5G core network (CN) and the SPs data networks still remains. In this paper, we introduce a zero- knowledge proof (ZKP) authentication algorithm called Partial- ID ZKP that authenticates users without revealing their service credentials. We show that Partial-ID ZKP has completeness and soundness properties. Based on Partial-ID ZKP, we then propose an extensible authentication protocol called EAP-ZKP that can be used in primary and secondary authentications to mitigate DDoS attacks at the CN edge. Finally, as a proof of concept, we implement EAP-ZKP in the 5G authentication procedure. Using the 5G simulators free5GC and gnbsim, we show that EAP-ZKP significantly reduces the authentication time for fake authentication attempts during DDoS attacks. Results also demonstrate that EAP-ZKP is able to recognize DDoS attack authentication attempts in about 10 msec. Interestingly, for the legitimate authentication attempts, the average authentication time slightly increases from 3.05 sec in current 5G authentication protocols to 3.06 sec in EAP-ZKP. This indicates that EAP-ZKP is promising for Beyond 5G.

Jakob Jakob Povšič, Andrej Brodnik

Zero-Knowledge proofs (ZKPs) enable proving of mathematical statements, revealing nothing but their validity. We design an authentication sys-tem with a ZKP as a password verification mech-anism within the Extensible Authentication Pro-tocol (EAP) framework. Designing a secure pass-word authentication system requires us to adopt security practices for protecting ourselves against the vulnerabilities of passwords. Integrating said practices is not trivial because of the tight cou-pling with the password verification method.

Jie Zhang, Futai Zhang

In the new paradigm of blockchain-powered intelligent edge, the key agreement is a significant problem that has not been extensively studied so far. Existing key agreement protocols in the traditional public-key setting are usually too complicated and heavy for edge and end devices. Besides, most protocols in use do not have effective measures to resist side-channel attacks, which are increasingly threatening cloud servers, edge devices, and end devices. Identity (ID)-based protocols can be conveniently implemented in the blockchain-powered intelligent edge. Several leakage-resilient ID-based protocols, which can resist side-channel attacks, have been proposed. However, they all involve time-consuming pairing computations. Besides, none of them address side-channel attacks to the key generation center (KGC). This article designs and realizes two novel ID-based key agreement protocols for the blockchain-powered intelligent edge, including an extended Canetti-Krawczyk (eCK) secure ID-based authenticated key agreement (AKA) protocol and a continuous after-the-fact leakage-resilient eCK (CAFL-eCK) secure ID-based AKA protocol. Both protocols do not involve any heavy pairing computation. Besides, the second one can resist side-channel attacks to the KGC and the communicating parties. A hybrid implementation of the two protocols can achieve high efficiency and strong security at the same time in blockchain-powered intelligent edge environments. This is demonstrated via a use case of a blockchain-powered smart home.

Dimitris Mouris, Charles Gouert, Nektarios Georgios Tsoutsos

The rapid growth of the globalized integrated circuit (IC) supply chain has drawn the attention of numerous malicious actors that try to exploit it for profit. One of the most prominent targets of such parties is the third-party intellectual property (3PIP) vendors and their circuit designs. With the increasing number of transactions between vendors and system integrators, the threat of IP reuse and piracy has become a significant consideration for the IC industry. What is more, the correctness of 3PIP designs should be verified before integration, imposing another challenge for 3PIP vendors since they have to prove the functionality of their designs to system integrators while protecting the privacy of the circuit implementations. To eliminate this deadlock, we utilize the cryptographic technique of “zero-knowledge proofs” to enable 3PIP vendors to convince system integrators about various functional properties of a circuit (e.g., area, power, and frequency) without disclosing its netlist (i.e., in zero-knowledge). Our approach comprises a circuit compiler that transforms arbitrary netlists into a zero knowledge-friendly format and a library of modules that provide cryptographic guarantees for various properties of the netlist while hiding the actual gates. We evaluate our method using combinational and sequential circuits from the ISCAS and ITC benchmark suites.

Shaofen Xie, Wang Yao, Faguo Wu, Zhiming Zheng

Lattice-based non-interactive zero-knowledge proof has been widely used in one-way communication and can be effectively applied to resist quantum attacks. However, lattice-based non-interactive zero-knowledge proof schemes have long faced and paid more attention to some efficiency issues, such as proof size and verification time. In this paper, we propose the non-interactive zero-knowledge proof schemes from RLWE-based key exchange by making use of the Hash function and public-key encryption. We then show how to apply the proposed schemes to achieve the fixed proof size and rapid public verification. Compared with previous approaches, our schemes can realize better effectiveness in proof size and verification time. In addition, the proposed schemes are secure from completeness, soundness, and zero-knowledge.