Blockchain Papers

Masayuki Abe, Charanjit S. Jutla, Miyako Ohkubo, Jiaxin Pan · 6 authors

No abstract is available for this record.

Daniel Kales, Sebastian Ramacher, Christian Rechberger, Roman Walch · 5 authors

Post-quantum cryptography has received increased attention in recent years, in particular, due to the standardization effort by NIST. One of the second-round candidates in the NIST post-quantum standardization project is Picnic, a post-quantum secure signature scheme based on efficient zero-knowledge proofs of knowledge. In this work, we present the first FPGA implementation of Picnic. We show how to efficiently calculate LowMC, the block cipher used as a one-way function in Picnic, in hardware despite the large number of constants needed during computation. We then combine our LowMC implementation and efficient instantiations of Keccak to build the full Picnic algorithm. Additionally, we conform to recently proposed hardware interfaces for post-quantum schemes to enable easier comparisons with other designs. We provide evaluations of our Picnic implementation for both, the standalone design and a version wrapped with a PCIe interface, and compare them to the state-of-the-art software implementations of Picnic and similar hardware designs. Concretely, signing messages on our FPGA takes 0.25 ms for the L1 security level and 1.24 ms for the L5 security level, beating existing optimized software implementations by a factor of 4.

Rafaël del Pino, Vadim Lyubashevsky, Gregor Seiler

No abstract is available for this record.

Guilhem Castagnos, Dario Catalano, Fabien Laguillaumie, Federico Savasta · 5 authors

No abstract is available for this record.

Vincenzo Iovino, Ivan Visconti

The Fiat-Shamir (FS) transform is a well known and widely used technique to convert any constant-round public-coin honest-verifier zero-knowledge (HVZK) proof or argument system \(\mathsf {HVZK}=(\mathcal {P},\mathcal {V})\) in a non-interactive zero-knowledge (NIZK) argument system

Giulio Malavolta, Pedro Moreno-Sánchez, Clara Schneidewind, Aniket Kate · 5 authors

Tremendous growth in cryptocurrency usage is exposing the inherent scalability issues with permissionless blockchain technology. Payment-channel networks (PCNs) have emerged as the most widely deployed solution to mitigate the scalability issues, allowing the bulk of payments between two users to be carried out off-chain. Unfortunately, as reported in the literature and further demonstrated in this paper, current PCNs do not provide meaningful security and privacy guarantees

Dimaz Ankaa Wijaya, Joseph K. Liu, Ron Steinfeld, Dongxi Liu

Monero is one of the privacy-preserving cryptocurrencies employing CryptoNote protocol. The privacy features in Monero are provided by cryptographic techniques such as linkable ring signature and one-time public key. Recent studies show that the majority of Monero inputs are traceable prior to mandatory RingCT transaction. After the RingCT was implemented, the problems were mitigated. We propose a novel attack to reduce the anonymity of Monero transactions or even to fully deanonymise the inputs. The proposed protocol can be launched in RingCT protocol and enables multiple attackers to collaborate without trusting each other. The attack scheme can be planted in the existing Monero services without extra fees and without putting the users' money at risk.

Domhnall Carlin, Philip OrKane, Sakir Sezer, Jonah Burgess

With the rise in worth and popularity of cryptocurrencies, a new opportunity for criminal gain is being exploited and with little currently offered in the way of defence. The cost of mining (i.e., earning cryptocurrency through CPU-intensive calculations that underpin the blockchain technology) can be prohibitively expensive, with hardware costs and electrical overheads previously offering a loss compared to the cryptocurrency gained. Off-loading these costs along a distributed network of machines via malware offers an instantly profitable scenario, though standard Anti-virus (AV) products offer some defences against file-based threats. However, newer fileless malicious attacks, occurring through the browser on seemingly legitimate websites, can easily evade detection and surreptitiously engage the victim machine in computationally-expensive cryptomining (cryptojacking). With no current academic literature on the dynamic opcode analysis of cryptomining, to the best of our knowledge, we present the first such experimental study. Indeed, this is the first such work presenting opcode analysis on non-executable files. Our results show that browser-based cryptomining within our dataset can be detected by dynamic opcode analysis, with accuracies of up to 100%. Further to this, our model can distinguish between cryptomining sites, weaponized benign sites, de-weaponized cryptomining sites and real world benign sites. As it is process-based, our technique offers an opportunity to rapidly detect, prevent and mitigate such attacks, a novel contribution which should encourage further future work.

Albert Guan, Wen-Guey Tzeng

No abstract is available for this record.

Michiel Van Beirendonck, Louis-Charles Trudeau, Pascal Giard, Alexios Balatsoukas‐Stimming

Lyra2REv2 is a hashing algorithm that consists of a chain of individual hashing algorithms and it is used as a proof-of-work function in several cryptocurrencies that aim to be ASIC-resistant. The most crucial hashing algorithm in the Lyra2REv2 chain is a specific instance of the general Lyra2 algorithm. In this work we present the first FPGA implementation of the aforementioned instance of Lyra2 and we explain how several properties of the algorithm can be exploited in order to optimize the design.

Michiel Van Beirendonck, Pascal Giard, Alexios Balatsoukas‐Stimming

No abstract is available for this record.

Mohammad Ahmad, Abdullah Al-Saleh, Fahad A. Al Masoud

Cryptocurrency subject attracted so many people for the last eight years around the globe. Satoshi’s Nakamoto’s, the founder of the bitcoin cryptocurrency behind this revolutionary change in digital money market. Bitcoin cryptocurrency uses “Power of Work” or simply PoW system as its mining algorithm. But in January of 2016, Ethereum cryptocurrency has launched which adopted a new system called “Power of Stake” or simply PoS that is used in Ethereum as its mining algorithm. This paper explores and compares PoW and PoS systems that is used widely today in cryptocurrencies digital money, concluding the pros and cons for each system with enabling to decide which one is more suitable and stable in digital money market.

А.А. Онацкий, Oksana Zharovа

Proposed cryptographic protocol with zero-knowledge proof on elliptic curves using one-way hash function, allowing to establish the truth of allegation and does not convey any additional information about the approval. Cryptographic protocols based on zero-knowledge proof allow identification, key exchange and other cryptographic operations to be performed without leakage of sensitive information during the information exchange. The implementation of the cryptographic protocol of the zero-knowledge proof on the basis of the mathematical apparatus of elliptic curves allows to significantly reduce the size of the protocol parameters and increase the cryptographic stability (computational complexity of the hacking problem). The security of cryptosystems on elliptic curves is based on the difficulty of solving the elliptic curve discrete logarithm problem. The completeness and correctness of the protocol is determined in the work, an example of calculation is given, the cryptographic protocol is modeled on the High-Level Protocol Specification Language, the model validation and verification of the protocol are performed. Software verification of the cryptographic protocol was performed using the software modules On the Fly Model Checker and Constraint Logic based Attack Searcher. To validation the cryptographic protocol for resistance to intruder attacks was used the Security Protocol Animator package for Automated Validation of Internet Security Protocols and Applications. The security of the proposed cryptographic protocol is based on the difficulty of solving the elliptic curve discrete logarithm problem and the cryptographic stability of the hash function. To implement the cryptographic protocol, you can use the recommended elliptical curves according to DSTU 4145-2000 and the hash function GOST 34.311-95.

Edgar González Fernández, Guillermo Morales-Luna, Feliú Sagols Troncoso

Zero-Knowledge Proofs ZKP provide a reliable option to verify that a claim is true without giving detailed information other than the answer. A classical example is provided by the ZKP based in the Graph Isomorphism problem (GI), where a prover must convince the verifier that he knows an isomorphism between two isomorphic graphs without publishing the bijection. We design a novel ZKP exploiting the NP-hard problem of finding the algebraic ideal of a multivariate polynomial set, and consequently resistant to quantum computer attacks. Since this polynomial set is obtained considering instances of GI, we guarantee that the protocol is at least as secure as the GI based protocol.

Norsefire, ToCsIcK

This paper introduces the underlying mechanics and interface for PhoeniχCoin (PHX), an Ethereum ERC223-compliant cryptocurrency. The supply of PHX tokens is tied directly to the Ethereum balance of the smart contract underpinning the ‘EthPhoenix’ decentralised application, and mined using a novel, generalisable technique we refer to as proof-of-volatility.

Jia Liu, Tibor Jager, Saqib A. Kakvi, Bogdan Warinschi

Time-lock encryption is a method to encrypt a message such that it can only be decrypted after a certain deadline has passed. We propose a novel time-lock encryption scheme, whose main advantage over prior constructions is that even receivers with relatively weak computational resources should immediately be able to decrypt after the deadline, without any interaction with the sender, other receivers, or a trusted third party. We build our time-lock encryption on top of the new concept of computational reference clocks and an extractable witness encryption scheme. We explain how to construct a computational reference clock based on Bitcoin. We show how to achieve constant level of multilinearity for witness encryption by using SNARKs. We propose a new construction of a witness encryption scheme which is of independent interest: our scheme, based on Subset-Sum , achieves extractable security without relying on obfuscation. The scheme employs multilinear maps of arbitrary order and is independent of the implementations of multilinear maps.

David Derler, Daniel Slamanig

No abstract is available for this record.

Songjie Wei, Shuai Li, Peilong Liu, Meilin Liu

LEO constellation has received intensive research attention in the field of satellite communication. The existing centralized authentication protocols traditionally used for MEO/GEO satellite networks cannot accommodate LEO satellites with frequent user connection switching. This paper proposes a fast and efficient access verification protocol named BAVP by combining identity-based encryption and blockchain technology. Two different key management schemes with IBE and blockchain, respectively, are investigated, which further enhance the authentication reliability and efficiency in LEO constellation. Experiments on OPNET simulation platform evaluate and demonstrate the effectiveness, reliability, and fast-switching efficiency of the proposed protocol. For LEO networks, BAVP surpasses the well-known existing solutions with significant advantages in both performance and scalability which are supported by theoretical analysis and simulation results.

Dakshita Khurana

The notion of simulation is central to cryptography: often, to demonstrate that an adversary did not recover any information about private inputs of other participants, we exhibit the existence of a simulator that generates the adversary's view without access to inputs of honest participants. The primary method used to build simulators is rewinding, where a simulator resets the adversary to a previous point in the protocol and tries to complete the protocol tree multiple times until it achieves a favorable outcome.First introduced in the context of zero-knowledge proof systems and secure computation, today the rewinding technique is synonymous with protocol security and polynomial simulation. Prior to this work, all known rewinding techniques in the plain model required multiple rounds of back-and-forth interaction between participants.In this thesis, we demonstrate the first rewinding techniques that require only a single message from each participant. Using these techniques, we overcome several barriers from literature to construct for the first time, based on standard sub-exponential cryptographic assumptions, the following core protocols, and several subsequent applications:- Two message commitments satisfying non-malleability (with respect to commitment).- Two-message delayed-input weak zero-knowledge arguments for NP. These imply arguments for NP satisfying witness hiding and strong witness indistinguishability.

Jan Hajný, Petr Dzurenda, Lukáš Malina

Card‐based physical access control systems are used by most people on a daily basis, for example, at work, in public transportation, or at hotels. Yet these systems have often very poor cryptographic protection. User identifiers and keys can be easily eavesdropped on and counterfeited. The privacy‐preserving features are almost missing in these systems. To improve this state, we propose a novel cryptographic scheme based on efficient zero‐knowledge proofs and Boneh‐Boyen signatures. The proposed scheme is provably secure and provides the full set of privacy‐enhancing features, that is, the anonymity, untraceability, and unlinkability of users. Furthermore, our scheme supports distributed multidevice authentication with multiple RFID (Radio‐Frequency IDentification) user devices. This feature is particularly important in applications for controlling access to dangerous sites where the presence of protective equipment is checked during each access control session. Besides the full cryptographic specification, we also show the results of our implementation on devices commonly used in access control applications, particularly the smart cards and embedded verification terminals. By avoiding costly operations on user devices, such as bilinear pairings, we were able to achieve times comparable to existing systems (around 500 ms), while providing significantly higher security, privacy protection, and features for RFID multidevice authentication.

Rafail Ostrovsky, Giuseppe Persiano, Daniele Venturi, Ivan Visconti

No abstract is available for this record.

Jonathan Katz, Vladimir Kolesnikov, Xiao Wang

Recent work, including ZKBoo, ZKB++, and Ligero, has developed efficient non-interactive zero-knowledge proofs of knowledge (NIZKPoKs) for Boolean circuits based on symmetric-key primitives alone, using the "MPC-in-the-head" paradigm of Ishai et al. We show how to instantiate this paradigm with MPC protocols in the preprocessing model; once optimized, this results in an NIZKPoK with shorter proofs (and comparable computation) as in prior work for circuits containing roughly 300--100,000 AND~gates. In contrast to prior work, our NIZKPoK also supports witness-independent preprocessing, which allows the prover to shift most of its work to an offline phase before the witness is known. We use our NIZKPoK to construct a signature scheme based only on symmetric-key primitives (and hence with "post-quantum" security). The resulting scheme has shorter signatures than the scheme built using ZKB++ (and comparable signing/verification time), and is even competitive with hash-based signature schemes. To further highlight the flexibility and power of our NIZKPoK, we also use it to build efficient ring and group signatures based on symmetric-key primitives alone. To our knowledge, the resulting schemes are the most efficient constructions of these primitives that offer post-quantum security.

Tao Li, Donghwa Shin, Baolian Wang

Abstract We document numerous occurrences of pump-and-dump schemes (P&Ds) targeting cryptocurrencies, which tend to trigger short-term episodes that feature dramatic increases in prices, volume, and volatility, followed by quick reversals. The evidence we document, including price run-ups before P&Ds start, suggests wealth transfers from outsiders to insiders. Our findings based on wallet-level data are consistent with the reasoning that gambling preferences, overconfidence, and naïve reinforcement learning help explain P&D participation. Finally, exploiting two natural experiments in which exchanges altered P&D policies, we find evidence consistent with the idea that P&Ds contribute to reduced cryptocurrency liquidity and lower prices.

Huige Li, Fangguo Zhang, Jiejie He, Haibo Tian

At present, the cloud storage used in searchable symmetric encryption schemes (SSE) is provided in a private way, which cannot be seen as a true cloud. Moreover, the cloud server is thought to be credible, because it always returns the search result to the user, even they are not correct. In order to really resist this malicious adversary and accelerate the usage of the data, it is necessary to store the data on a public chain, which can be seen as a decentralized system. As the increasing amount of the data, the search problem becomes more and more intractable, because there does not exist any effective solution at present. In this paper, we begin by pointing out the importance of storing the data in a public chain. We then innovatively construct a model of SSE using blockchain(SSE-using-BC) and give its security definition to ensure the privacy of the data and improve the search efficiency. According to the size of data, we consider two different cases and propose two corresponding schemes. Lastly, the security and performance analyses show that our scheme is feasible and secure.