Blockchain Papers

Usman W. Chohan

No abstract is available for this record.

Felix Truger

Ordinos is a novel verifiable tally-hiding e-voting system. At its heart, a homomorphic encryption scheme and secure multi-party computation (MPC) are used to tally votes and securely determine the voting result, without necessarily revealing the full tally (e.g., the number of votes per candidate)The proof of concept implementation of Ordinos is based on a threshold variant of the Paillier encryption scheme and two MPC protocols for the comparison of encrypted numbers (greater-than and equality). Due to the threshold construction, the decryption key is shared among a set of trustees. The MPC protocols for comparison require precomputed encrypted randomness of certain shape. Formerly, a trusted party was employed to generate the key shares and randomness and distribute them to the trustees. In this thesis, the trusted party was replaced by MPC protocols that allow to generate the key shares and randomness among the trustees. The protocols provide security against malicious parties in the honest-majority setting. The key generation follows a proposal by Nishide and Sakurai (2010) that is based on verifiable secret sharings and zero-knowledge proofs for committed values. We introduce a few adaptations to reduce its runtime using mostly standard techniques. The generation of randomness is based on the Paillier encryption scheme as an arithmetic black box and standard zero-knowledge proofs for Paillier encrypted values. The protocols were implemented and their performance was evaluated in a local network. Most notablythe implemented key generation protocol for threshold Paillier showed an expected average runtime around 95 minutes for generating 2048-bit keys among 3 trustees with a threshold of 2. Since existing implementations provide security only in the semi-honest setting, this is the first time that an approach with security against malicious parties was implemented and evaluated. Overall, the distributed generation of both key shares and randomness takes considerably more time compared to the use of a trusted party, but avoids security risks and trust problems that occur with trusted parties.

Zihan Yang, Bo Qin, Qianhong Wu, Wenchang Shi · 5 authors

No abstract is available for this record.

Philipp Jakubeit, A Dercksen, Peter Andreas

No abstract is available for this record.

Jonathan Bootle, Anja Lehmann, Vadim Lyubashevsky, Gregor Seiler

No abstract is available for this record.

Peter Fenteany, Benjamin Fuller

No abstract is available for this record.

Віктор Петрович Бойко, Віктор Бойко

Стаття присвячена дослідженню передумов появи децентралізованих
\nплатіжних систем. Історичні події та наукові досягнення було поділено на періоди за
\nтехнологічними прийомами шифрування, що застосовувались в різні часи. Перший
\nперіод (приблизно з 3-го тисячоліття до нашої ери) — це період моноалфавітних
\nшифрів, основний принцип яких полягав у заміні алфавіту вихідного тексту іншим
\nалфавітом через заміну букв іншими буквами або символами. Другий період (приблизно з ІХ століття нашої ери) пов’язаний з появою різних варіантів поліалфавітних
\nшифрів. Третій період (перша половина XX століття) характеризується впровадженням електромеханічних пристроїв. При цьому тривало використання поліалфавітних шифрів. Наступним є період переходу до математичної криптографії (з
\nсередини 1970-х до кінця 1990-х років XX століття) завдяки поширенню способу
\nкриптографії з відкритим ключем.
\nУ статті досліджено історію руху Шифропанків та ідеологію, яка була проголошена у
\nманіфестах Тімоті Мея та Еріка Хьюза. У цих маніфестах визнається, що приватність — це сила вибіркового розкриття особистості світу і діяльність руху Цифропанків спрямована на побудову анонімних систем для захисту конфіденційності, анонімних систем пересилання пошти, цифрових підписів і електронних грошей.
\nТакож проаналізовано роботу сучасних децентралізованих платіжних систем і визначено, що системи на основі алгоритму Proof-of-work засновані на обчислювальній потужності обладнання. Більшість нових блокчейн проектів йдуть дешевшим
\nшляхом і використовують алгоритм Proof-of-stake. Функціональні криптоактиви — це
\nлише операційне середовище, що дозволяє передачу певної вартості між користувачами без будь-яких посередників та без необхідності довіряти один одному або
\nнадавати персональні дані. Гібридні (змішані) криптоактиви — це змішані концепції,
\nякі можуть мати або гібридну систему консенсусу в мережі, або можуть поєднувати
\nдва чи навіть кілька функціональних криптоактива. А от цифрова валюта центральних банків поки що не має практичної реалізації, але її запровадження активно просувається.
\nThe article is devoted to the research of prerequisites for the emergence of
\ndecentralized payment systems. Historical events and scientific developments have been divided into periods by technological encryption techniques used at different times. The
\nfirst period (from about the 3rd millennium BC) is the period of mono-alphabetic ciphers,
\nthe basic principle of which is to replace the alphabet of the original text with another
\nalphabet by replacing letters with other letters or symbols. The second period
\n(approximately from the 9th century AD) is associated with the emergence of different
\nvariants of polyalphabetic ciphers. The third period (the first half of the XX century.) is
\ncharacterized by the introduction of electromechanical devices. At the same time, the use
\nof poly-alphabetic ciphers continued. The next is the period of transition to mathematical
\ncryptography (from the mid-1970s to the end of the 1990s) due to the spread of open-key
\ncryptography.
\nThis article has analyzed the history of the Cypherpunk’s movement and ideology, which
\nwas proclaimed by Timothy May and Eric Hughes. In their manifestos acknowledge that
\nprivacy is the power to selectively reveal oneself to the world and the activities of the
\nCypherpunk’s movement are aimed at building anonymous privacy protection systems,
\nanonymous mail forwarding systems, digital signatures and electronic money.
\nAlso has been analyzed the modern decentralized payment systems and it is determined
\nthat the systems on the Proof-of-work algorithm are based on the computing power of the
\nequipment. Most new blockchain projects go the cheaper way and use the Proof-of-stake
\nalgorithm. Functional crypto-assets are just an operating environment that allows the
\ntransfer of value between users without any intermediaries and without the need to trust
\none another or provide personal information. Hybrid (mixed) crypto-assets are mixed
\nconcepts and can either have a hybrid network consensus system or can combine two or
\neven several functional crypto-assets. Currently the digital currency of the central banks
\nhas not been practically implemented, but its introduction is actively advancing.

Juan Zhao, Tianrui Zong, Yong Xiang, Longxiang Gao · 5 authors

No abstract is available for this record.

Alexandre Augusto Giron, Jean Everson Martina, Ricardo Felipe Custódio

No abstract is available for this record.

Léo Robert, Daiki Miyahara, Pascal Lafourcade, Takaaki Mizuki

International audience

Alexandr Kuznetsov, Kyryl Shekhanin, Andrii Kolhatin, Diana Kovalchuk · 6 authors

The main cryptographic primitives in blockchain networks are hashing functions that are designed to form short and unpredictable digests for the message entered. In blockchain networks, hashing is used to build linked block lists, which provide safe and secure storage of important information in a distributed repository. The peculiarity of the hash search problem in blockchain networks allows applying the maximum parallelization of calculations, what good are multithreaded graphics processors (GPUs). In this paper, we explore the performance of GOST 34.311, STRIBOG, KECCAK, SHA2, RIPEMD160, Blake2b, and Whirlpool cryptographic hashing algorithms. HashCat software and various GPUs were used for comparative analysis of efficiency. GPUs were used: Geforce 740M 2GB; Geforce GTX1050ti 4GB; Rx580 Aorus 4GB; Rx580 Sapphire Pulse 8GB; Sapphire Vega 56 8GB.

MOSES DOGONYARO NOEL, Onomza Victor Waziri, Shafi’i Muhammad Abdulhamid, Adebayo Joseph Ojeniyi

Modern computing devices use classical algorithms such as Rivest Shamir Adleman (RSA) and Elliptic Curve Digital Signature Algorithm (ECDSA) for their security. The securities of these algorithms relied on the problem and difficulty of integer factorization and also calculating the Discrete Logarithm Problems. With the introduction of quantum computers, recent research is focusing on developing alternative algorithms which are supposed to withstand attacks from quantum computers. One of such alternatives is the Hash-based Digital Signature Schemes. Chosen hash-based signature schemes over classical algorithms is because their security is on the hash function used and that they are metaheuristic in nature. This research work presents basic analysis and the background understanding of Stateful Hash-based Signature Schemes, particularly the Lamport One-Time Signature Scheme, Winternitz One-Time Signature Scheme, and the Merkle Signature Scheme. The three schemes selected are stateful, hence has common features and are few-time hash-based signature schemes. The selected Stateful Hash-based Digital Signature Schemes were analyzed based on their respective key generation, signature generation, signature verification, and their security levels. Practical working examples were given for better understanding. With the analyses, Merkle Signature Scheme proves to be the best candidate to be used in the Bitcoin Proof of Work protocol because of its security and its advantage of signing many messages.

Hossein Rezaeighaleh, Cliff C. Zou

Bitcoin and other cryptocurrencies have become popular and motivate more hackers to steal digital funds. Users protect their private keys using crypto wallets to keep their funds safe from hackers. While the most secure option is hardware wallet, it suffers from lack of a secure and convenient backup and recovery process. Almost all existing wallets use mnemonics to back up the private keys, and a user must write down these words on a piece of paper. This approach is not only inconvenient but also problematic since the paper could be lost or stolen, resulting in a hacker recovering the keys. In this paper, we propose a new digital scheme to securely back up a hardware wallet relying on the side-channel human visual verification enabled by display screen on a hardware wallet. Using this method, we transfer the root of private keys from one hardware wallet to another wallet securely even via an untrusted terminal, such as a smartphone. At the end of this process, the user has two hardware wallets with the same private keys while she may use one of them as the main wallet and another one as a backup wallet.

Kancharla Abhilash, Nohpill Park

This paper proposes an analytical approach how to design and realize a crypto computing (Ethereum blockchain-based) under stringent real-time requirement. In order to evaluate the efficacy of the approach, a new analytical metric is defined and developed to estimate the dependability, referred to as the block-dependability. The proposed block-dependability precisely models the probability for the pending transactions to be posted within the current, in other words, within the target block delay, namely, within the deadline required if their expected execution times are within the temporal range of the deadline. Various methods how to prioritize and select transactions in the pending transaction pool in order to facilitate those transactions to be executed within their deadline requirements, such as the normal, random, sorted, and stratified, are proposed and simulated. A set of performance variables, or parameters, such as the number of pending transactions in the pool, the average speed of the transactions, gas fees, deadlines as well as the number of miners, are identified and taken into the block-dependability in order to reveal the influence of each variable on the block-dependability, versus each of those proposed prioritization and selection methods. Extensive parametric simulations are conducted and results are observed and discussed in the cases of the random transaction selection method and the sorted.

Srinjoy Mahato, Tanmoy Khatua, Ankan Das, Tathagata Roy Chowdhury

No abstract is available for this record.

Daiki Miyahara, Tatsuya Sasaki, Takaaki Mizuki, Hideaki Sone

Kakuro is a popular logic puzzle, in which a player fills in all empty squares with digits from 1 to 9 so that the sum of digits in each (horizontal or vertical) line is equal to a given number, called a clue, and digits in each line are all different. In 2016, Bultel, Dreier, Dumas, and Lafourcade proposed a physical zero-knowledge proof protocol for Kakuro using a deck of cards; their proposed protocol enables a prover to convince a verifier that the prover knows the solution of a Kakuro puzzle without revealing any information about the solution. One possible drawback of their protocol would be that the protocol is not perfectly extractable, implying that a prover who does not know the solution can convince a verifier with a small probability; therefore, one has to repeat the protocol to make such an error become negligible. In this paper, to overcome this, we design zero-knowledge proof protocols for Kakuro having perfect extractability property. Our improvement relies on the ideas behind the copy protocols in the field of card-based cryptography. By executing our protocols with a real deck of physical playing cards, humans can practically perform an efficient zero-knowledge proof of knowledge for Kakuro.

Stefan Kölbl, Elmar Tischhauser, Patrick Derbez, Andrey Bogdanov

No abstract is available for this record.

Narasimham Challa

In the digital world, the crypto currency has to do with the use of tokens based on the distributed ledger technology in a secure manner. Crypto currency can be a resource on a block chain network or can be seen as a tool to perform the transactions ensuring the privacy and security. Data may be available in temporal or text format. This paper describes about the distributed architecture for secure and attack-resilient bit coin-based crypto currency transactions for classified temporal and text data. The temporal data may be voice, sound or graphical information basing on the time series. If the data available is temporal this work describes about how it can be classified into a processed form. In this context, this paper describes the process of converting temporal data into text data. Further, the paper describes about the process of ensuring the security. This paper describes about the methodologies of cryptography-based hashing, attack-resilient nonce generation and verifiable encryption techniques for the construction of resilient transactions against stealthy data-integrity attack.

Sarala Ghimire, Jae Young Choi, Bumshik Lee

A video record plays a crucial role in providing evidence for crime scenes or road accidents. However, the main problem with the video record is that it is often vulnerable to various video tampering attacks. Although visual evidence is required to conduct an integrity verification before investigations, it is still difficult for human vision to detect a forgery. In this paper, we propose a novel video integrity verification method (IVM) that takes advantage of a blockchain framework. The proposed method employs an effective blockchain model in centralized video data, by combining a hash-based message authentication code and elliptic curve cryptography to verify the integrity of a video. In our method, video content with a predetermined size (segments) is key-hashed in a real-time manner and stored in a chronologically chained fashion, thus establishing an irrefutable database. The verification process applies the same procedure to the video segment and generates a hash value that can be compared with the hash in the blockchain. The proposed IVM is implemented on a PC environment, as well as on an accident data recorder-embedded system for verification. The experimental results show that the proposed method has better detection capabilities and robustness toward various kinds of tampering, such as copy–move, insert, and delete, as compared to other state-of-the-art methods. An analysis based on execution time along with an increase in the number of blocks within the blockchain shows a minimal overhead in the proposed method.

Lucas Bouvarel, Rafael Páez

In this paper we give an overview of the Blockchain. We explain quickly how it works thanks to the hash function and the distributed architecture. Then come the descriptions of the two most famous consensus algorithms: Proof of Work and Proof of Stake. We also present some security issues for each algorithm. This paper contains a little explanation of others consensus algorithms that are inspired of these two. Finally, a new consensus algorithm for private Blockchain is presented.

Jean-François Têtu, Louis-Charles Trudeau, Michiel Van Beirendonck, Alexios Balatsoukas‐Stimming · 5 authors

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. The most crucial and exotic hashing algorithm in the Lyra2REv2 chain is a specific instance of the general Lyra2 algorithm. This work presents the first hardware implementation of the specific instance of Lyra2 that is used in Lyra2REv2. Several properties of the aforementioned algorithm are exploited in order to optimize the design. In addition, an FPGA-based hardware implementation of a standalone miner for Lyra2REv2 on a Xilinx Multi-Processor System on Chip is presented. The proposed Lyra2REv2 miner is shown to be significantly more energy efficient than both a GPU and a commercially available FPGA-based miner. Finally, we also explain how the simplified Lyra2 and Lyra2REv2 architectures can be modified with minimal effort to also support the recent Lyra2REv3 chained hashing algorithm.

Omar A. Dawood, Othman I. Hammadi, Falath M. Mohammed

This paper proposes a new symmetric secret-key cipher for construction of block cipher model. This new approach is considered as a smart step that can be applied to the long process research of modern designing methods used in developing earlier symmetric algorithms. The present cipher can encrypt block lengths of 128-bit by employing Substitution-Permutation Network (SPN) structure. The present cipher uses three options of strong ciphering-key along with variable lengths of 192-bit for 12 rounds, 128-bit for 10 rounds and long ciphering key of 256-bit for 14 rounds similar to standard ciphers. The proposed algorithm has been designed to trust applications that are based on Bitcoin and crypto-currencies. The current algorithm intended to encrypt addresses of Bitcoin wallet that work quite similar to the e-mail address. The bitcoin wallet includes sensitive information like private secret keys and derived password that are highly confidential. The Advance Encryption Standard (AES) is employed to encrypt most of the bitcoin wallet database. The proposed cipher can act as a good substitute for the standard cipher that allows trusting the Bitcoin wallet database with high security and with a much more complex scheme. The key goal of the submitted algorithm is to build a new enhanced modern cipher with a secure and efficient applicable algorithm that can be used for crypto currencies applications employing a wide trail design strategy.

K. N. Pankov

Currently, blockchain data storage systems are considered promising for storing important information, including personal data. However, the requirements of modern legislation in various countries pose challenges to such systems, including the need to delete data at the request of users, which contradicts the very concept of the blockchain. One way to solve this problem is to use encryption. The paper presents the most powerful asymptotic estimates of the cardinality of sets of correlation-immune and (n,m,k)-resilient Boolean mappings that are used in the construction of stream encryption systems. Also, a recurrence relation is proved, allowing to calculate the number of (n,m,k)-resilient mappings for small values n, m and k.

Geogen George, Suresh Sankaranarayanan

Cryptography is the art of converting readable data into indecipherable format using keys and vice versa. Strength of the algorithm is mainly measured by the complexity and CPU cycles required for cryptanalysis in the algorithm. But in an energy constrained environment like IoT, CPU intense complex algorithms will degrade the efficiency. Light-weight or cut down versions of symmetric and asymmetric cryptographies are found best suited for constrained environments. So accordingly, we in this paper have surveyed a lot of Hardware and software based Light-weight cryptographic algorithms in a quest to find the best suited cryptographic algorithm for signing and hashing blockchain in a constrained environment.