October 2020 list
If you feel a paper should belong to another category, or that we missed a relevant paper just let us know. Participation is most welcome!
Categories:
- Attacks and defenses
- Blockchain-general
- Blockchain-noncrypto uses
- Financial
- Internet of Things (IoT)
- Proof of Work (PoW) alternatives
- Smart contracts
Attacks and defenses
Concentrated Stopping Set Design for Coded Merkle Tree: Improving Security Against Data Availability Attacks in Blockchain Systems
Authors: Debarnab Mitra, Lev Tauz, Lara Dolecek
Abstract: In certain blockchain systems, light nodes are clients that download only a small portion of the block. Light nodes are vulnerable to data availability (DA) attacks where a malicious node hides an invalid portion of the block from the light nodes. Recently, a technique based on erasure codes called Coded Merkle Tree (CMT) was proposed by Yu et al. that enables light nodes to detect a DA attack with high probability. The CMT is constructed using LDPC codes for fast decoding but can fail to detect a DA attack if a malicious node hides a small stopping set of the code. To combat this, Yu et al. used well-studied techniques to design random LDPC codes with high minimum stopping set size. Although effective, these codes are not necessarily optimal for this application. In this paper, we demonstrate a more specialized LDPC code design to improve the security against DA attacks. We achieve this goal by providing a deterministic LDPC code construction that focuses on concentrating stopping sets to a small group of variable nodes rather than only eliminating stopping sets. We design these codes by modifying the Progressive Edge Growth algorithm into a technique called the entropy-constrained PEG (EC-PEG) algorithm. This new method demonstrates a higher probability of detecting DA attacks and allows for good codes at short lengths.
Blockchain-general
Improving Bitcoin Transaction Propagation by Leveraging Unreachable Nodes
Authors: Federico Franzoni, Vanesa Daza
Abstract: The Bitcoin P2P network is at the core of all communications between clients. The reachable part of this network has been explored and analyzed by numerous studies. Unreachable nodes, however, are, in most part, overlooked. Nonetheless, they are a relevant part of the network and play an essential role in the propagation of messages. In this paper, we focus on transaction propagation and show that increasing the participation of unreachable nodes can potentially improve the robustness and efficiency of the network. In order to do that, we propose a few changes to the network protocol. Additionally, we design a novel transaction propagation protocol that explicitly involves unreachable nodes to provide better protection against deanonymization attacks. Our solutions are simple to implement and can effectively bring immediate benefits to the Bitcoin network.
How to Not Get Caught When You Launder Money on Blockchain?
Authors: G. Cuneyt Akcora, Sudhanva Purusotham, R. Yulia Gel, Mitchell Krawiec-Thayer, Murat Kantarcioglu
Abstract: The number of blockchain users has tremendously grown in recent years. As an unintended consequence, e-crime transactions on blockchains has been on the rise. Consequently, public blockchains have become a hotbed of research for developing AI tools to detect and trace users and transactions that are related to e-crime. We argue that following a few select strategies can make money laundering on blockchain virtually undetectable with most of the existing tools and algorithms. As a result, the effective combating of e-crime activities involving cryptocurrencies requires the development of novel analytic methodology in AI.
Blockchain-enabled Identity Verification for Safe Ridesharing Leveraging Zero-Knowledge Proof
Authors: Wanxin Li, Collin Meese, Hao Guo, Mark Nejad
Abstract: The on-demand mobility market, including ridesharing, is becoming increasingly important with e-hailing fares growing at a rate of approximately 130% per annum since 2013. By increasing utilization of existing vehicles and empty seats, ridesharing can provide many benefits including reduced traffic congestion and environmental impact from vehicle usage and production. However, the safety of riders and drivers has become of paramount concern and a method for privacy-preserving identity verification between untrusted parties is essential for protecting users. To this end, we propose a novel privacy-preserving identity verification system, extending zero-knowledge proof (ZKP) and blockchain for use in ridesharing applications. We design a permissioned blockchain network to perform the ZKP verification of a driver’s identity, which also acts as an immutable ledger to store ride logs and ZKP records. For the ZKP module, we design a protocol to facilitate user verification without requiring the exchange of any private information. We prototype the proposed system on the Hyperledger Fabric platform, with the Hyperledger Ursa cryptography library, and conduct extensive experimentation. To measure the prototype’s performance, we utilize the Hyperledger Caliper benchmark tool to perform extensive analysis and the results show that our system is suitable for use in real-world ridesharing applications.
Transaction Characteristics of Bitcoin
Authors: G. Befekadu Gebraselase, E. Bjarne Helvik, Yuming Jiang
Abstract: Blockchain has been considered as an important technique to enable secure management of virtual network functions and network slices. To understand such capabilities of a blockchain, e.g. transaction confirmation time, demands a thorough study on the transaction characteristics of the blockchain. This paper presents a comprehensive study on the transaction characteristics of Bitcoin — the first blockchain application, focusing on the underlying fundamental processes. A set of results and findings are obtained, which provide new insight into understanding the transaction and traffic characteristics of Bitcoin. As a highlight, the validity of several hypotheses/assumptions used in the literature is examined with measurement for the first time.
Flexible, Decentralized Access Control for Smart Buildings with Smart Contracts
Authors: Leepakshi Bindra, Kalvin Eng, Omid Ardakanian, Eleni Stroulia
Abstract: Large commercial buildings are complex cyber-physical systems containing expensive and critical equipment that ensure the safety and comfort of their numerous occupants. Yet occupant and visitor access to spaces and equipment within these buildings are still managed through unsystematic, inefficient, and human-intensive processes. As a standard practice, long-term building occupants are given access privileges to rooms and equipment based on their organizational roles, while visitors have to be escorted by their hosts. This approach is conservative and inflexible. In this paper, we describe a methodology that can flexibly and securely manage building access privileges for long-term occupants and short-term visitors alike, taking into account the risk associated with accessing each space within the building. Our methodology relies on blockchain smart contracts to describe, grant, audit, and revoke fine-grained permissions for building occupants and visitors, in a decentralized fashion. The smart contracts are specified through a process that leverages the information compiled from Brick and BOT models of the building. We illustrate the proposed method through a typical application scenario in the context of a real office building and argue that it can greatly reduce the administration overhead, while, at the same time, providing fine-grained, auditable access control.
Multi-factor authentication for users of non-internet based applications of blockchain-based platforms
Authors: Andrew Kinai, Fred Otieno, Nelson Bore, Komminist Weldemariam
Abstract: Attacks targeting several millions of non-internet based application users are on the rise. These applications such as SMS and USSD typically do not benefit from existing multi-factor authentication methods due to the nature of their interaction interfaces and mode of operations. To address this problem, we propose an approach that augments blockchain with multi-factor authentication based on evidence from blockchain transactions combined with risk analysis. A profile of how a user performs transactions is built overtime and is used to analyse the risk level of each new transaction. If a transaction is flagged as high risk, we generate n-factor layers of authentication using past endorsed blockchain transactions. A demonstration of how we used the proposed approach to authenticate critical financial transactions in a blockchain-based asset financing platform is also discussed.
Garou: An Efficient and Secure Off-Blockchain Multi-Party Payment Hub
Authors: Yongjie Ye, Weigang Wu
Abstract: To mitigate the scalability problem of decentralized cryptocurrencies such as Bitcoin and Ethereum, the payment channel, which allows two parties to perform secure coin transfers without involving the blockchain, has been proposed. The payment channel increases the transaction throughput of two parties to a level that is only limited by their network bandwidth. Recent proposals focus on extending the two-party payment channel to the N-party payment hub. Unfortunately, none of them can achieve efficiency, flexibility in the absence of a trusted third-party. In this paper, we propose Garou, a secure N-party payment hub that allows multiple parties to perform secure off-chain coin transfers. Except in the case of disputes, participants within the payment hub can make concurrent and direct coin transfers with each other without the involvement of the blockchain or any third-party intermediaries. This allows Garou to achieve both high-performance and flexibility. Garou also guarantees that an honest party always maintains its balance security against strong adversarial capabilities. To demonstrate the feasibility of the Garou protocol, we develop a proof of concept prototype for the Ethereum network. Our evaluation results show that the maximum transaction throughput of Garou is 20 times higher than that of state-of-art payment hubs.
PQ-Fabric: A Permissioned Blockchain Secure from Both Classical and Quantum Attacks
Authors: Bhargav Das, Amelia Holcomb, Michele Mosca, F. C. C. Geovandro Pereira
Abstract: Hyperledger Fabric is a prominent and flexible proposal for a permissioned distributed ledger platform. It supports modular consensus protocols, which allows for selecting distinct trust models and performance/throughput trade-offs. On the other hand, access control and identity management intrinsically relies on credentials issued by a Certificate Authority of a Membership Service Provider (MSP). The default MSP implementation, instantiated by the means of the the Blockchain Cryptographic Service Provider interface (BCCSP), only handles standard classical PKI methods for authentication and digital signatures, accommodating basically RSA and ECDSA classical signatures. Also only one single signature scheme is assumed to be employed at a given MSP instantiation. This makes the credential-related functions highly attached to single classical standard primitives. Unfortunately, it is well known that RSA and ECDSA are vulnerable to quantum attacks and an ongoing post-quantum standardization process run by NIST aims to identify quantum-safe drop-in replacements for such cryptographic primitives in a few years. In this paper, we propose a redesign of the credential-management procedures and related specifications in order to incorporate hybrid digital signatures (i.e., protection against both classical and quantum attacks using two signature schemes) that include the quantum-safe signatures from the upcoming NIST standards. We also validate our proposal by providing an implementation of Fabric along with the Open Quantum Safe library. Our implementation employs the crypto-agility concept,which allows for plugging in different algorithms in the MSP Credentials and performing comparative benchmarks with them. Moreover, our proposal is backwards compatible with the client implementations, and no SDK changes would be required for the client Node.JS code.
Game-theoric approach to decision-making problem for blockchain mining
Authors: Kosuke Toda, Naomi Kuze, Toshimitsu Ushio
Abstract: It is an important decision-making problem for a miner in blockchain networks if he/she does the mining so that he/she earns a reward by creating a new block earlier than the other miners. We formulate the decision-making problem as a non-cooperative game because the probability of creating blocks depends on not only his/her own computational resource but also other miners’ computational resources. By the theoretical and numerical analysis, we show a hysteresis phenomenon of Nash equilibria depending on the reward and a jump phenomenon of the decision of the miners by a slight change of the reward. We also show that the reward for which miners decide to quit mining becomes smaller as the number of miners increases.
Using Homomorphic hashes in coded blockchains
Authors: Doriane Perard, Xavier Goffin, Jérôme Lacan
Abstract: One of the scalability issues of blockchains is the increase of their sizes which can prevent users from storing them and thus from contributing to the decentralization effort. Recent works developed the concept of coded blockchains, which allow users to store only some coded fragments of the blockchains. However, this solution is not protected against malicious nodes that can propagate erroneous coded fragments. We propose in the paper to add homomorphic hashes to this system. This allows for instantaneous detection of erroneous fragments and thus avoids decoding with wrong data. We describe the integration of this mechanism in coded blockchains and we evaluate its complexity theoretically and by simulation.
Computationally sound Bitcoin tokens
Authors: Massimo Bartoletti, Stefano Lande, Roberto Zunino
Abstract: We propose a secure and efficient implementation of fungible tokens on Bitcoin. Our technique is based on a small extension of the Bitcoin script language, which allows the spending conditions in a transaction to depend on the neighbour transactions. We show that our implementation is computationally sound: that is, adversaries can make tokens diverge from their ideal functionality only with negligible probability.
Knowledge Discovery in Cryptocurrency Transactions: A Survey
Authors: Fan Xiao Liu, Xin-Jian Jiang, Si-Hao Liu, Kong Chi Tse
Abstract: Cryptocurrencies gain trust in users by publicly disclosing the full creation and transaction history. In return, the transaction history faithfully records the whole spectrum of cryptocurrency user behaviors. This article analyzes and summarizes the existing research on knowledge discovery in the cryptocurrency transactions using data mining techniques. Specifically, we classify the existing research into three aspects, i.e., transaction tracings and blockchain address linking, the analyses of collective user behaviors, and the study of individual user behaviors. For each aspect, we present the problems, summarize the methodologies, and discuss major findings in the literature. Furthermore, an enumeration of transaction data parsing and visualization tools and services is also provided. Finally, we outline several future directions in this research area, such as the current rapid development of Decentralized Finance (De-Fi) and digital fiat money.
Blockchain-noncrypto uses
Construction Payment Automation Using Blockchain-Enabled Smart Contracts and Reality Capture Technologies
Authors: Hesam Hamledari, Martin Fischer
Abstract: This paper presents a smart contract-based solution for autonomous administration of construction progress payments. It bridges the gap between payments (cash flow) and the progress assessments at job sites (product flow) enabled by reality capture technologies and building information modeling (BIM). The approach eliminates the reliance on the centralized and heavily intermediated mechanisms of existing payment applications. The construction progress is stored in a distributed manner using content addressable file sharing; it is broadcasted to a smart contract which automates the on-chain payment settlements and the transfer of lien rights. The method was successfully used for processing payments to 7 subcontractors in two commercial construction projects where progress monitoring was performed using a camera-equipped unmanned aerial vehicle (UAV) and an unmanned ground vehicle (UGV) equipped with a laser scanner. The results show promise for the method’s potential for increasing the frequency, granularity, and transparency of payments. The paper is concluded with a discussion of implications for project management, introducing a new model of project as a singleton state machine.
GFL: A Decentralized Federated Learning Framework Based On Blockchain
Authors: Yifan Hu, Wei Xia, Jun Xiao, Chao Wu
Abstract: With the increasing importance of data privacy protection, federated learning is becoming more widely used, and there are more frameworks for federated learning. However, the centralization of federated learning has always restricted the development of federated learning and the federated learning framework. Although there are some decentralized federated learning algorithms, these algorithms have some shortcomings and there is no framework that can quickly use these algorithms. In this paper,we proposed and implemented a blockchain-based decentralized federated learning framework called GFL \cite{GFL} and integrated two new blockchain-based decentralized federated learning mechanisms to try to try to make the decentralized federated learning algorithm better landed.
BBB-Voting: 1-out-of-k Blockchain-Based Boardroom Voting
Authors: Sarad Venugopalan, Ivan Homoliak, Zengpeng Li, Pawel Szalachowski
Abstract: Voting is a means to agree on a collective decision based on available choices (e.g., candidates), where participants (voters) agree to abide by their outcome. To improve trust in voting, decentralized solutions based on a blockchain can be employed. A blockchain ensures that all entities in the voting system have the same view of the actions made by others due to the immutable log. Existing blockchain-based boardroom voting implementation called Open Voting Network (OVN) supports only two candidates. We present a blockchain-based approach for decentralized 1-out-of-k voting and provide a cost-optimized implementation using Ethereum. We resolve the problem of stalling participants by a fault recovery protocol. Finally, we compare our implementation with OVN and show that our work decreases the costs for voters by 13.5% in terms of gas consumption.
BlockFLA: Accountable Federated Learning via Hybrid Blockchain Architecture
Authors: Bimal Harsh Desai, Safa Mustafa Ozdayi, Murat Kantarcioglu
Abstract: Federated Learning (FL) is a distributed, and decentralized machine learning protocol. By executing FL, a set of agents can jointly train a model without sharing their datasets with each other, or a third-party. This makes FL particularly suitable for settings where data privacy is desired. At the same time, concealing training data gives attackers an opportunity to inject backdoors into the trained model. It has been shown that an attacker can inject backdoors to the trained model during FL, and then can leverage the backdoor to make the model misclassify later. Several works tried to alleviate this threat by designing robust aggregation functions. However, given more sophisticated attacks are developed over time, which by-pass the existing defenses, we approach this problem from a complementary angle in this work. Particularly, we aim to discourage backdoor attacks by detecting, and punishing the attackers, possibly after the end of training phase. To this end, we develop a hybrid blockchain-based FL framework that uses smart contracts to automatically detect, and punish the attackers via monetary penalties. Our framework is general in the sense that, any aggregation function, and any attacker detection algorithm can be plugged into it. We conduct experiments to demonstrate that our framework preserves the communication-efficient nature of FL, and provide empirical results to illustrate that it can successfully penalize attackers by leveraging our novel attacker detection algorithm.
Securing Manufacturing Using Blockchain
Authors: Zahra Jadidi, Ali Dorri, Raja Jurdak, Colin Fidge
Abstract: Due to the rise of Industrial Control Systems (ICSs) cyber-attacks in the recent decade, various security frameworks have been designed for anomaly detection. While advanced ICS attacks use sequential phases to launch their final attacks, existing anomaly detection methods can only monitor a single source of data. Therefore, analysis of multiple security data can provide comprehensive and system-wide anomaly detection in industrial networks. In this paper, we propose an anomaly detection framework for ICSs that consists of two stages: i) blockchain-based log management where the logs of ICS devices are collected in a secure and distributed manner, and ii) multi-source anomaly detection where the blockchain logs are analysed using multi-source deep learning which in turn provides a system wide anomaly detection method. We validated our framework using two ICS datasets: a factory automation dataset and a Secure Water Treatment (SWAT) dataset. These datasets contain physical and network level normal and abnormal traffic. The performance of our new framework is compared with single-source machine learning methods. The precision of our framework is 95% which is comparable with single-source anomaly detectors.
A Secure and Efficient Approach for Issuing KYC Token As COVID-19 Health Certificate Based on Stellar Blockchain Network
Authors: Kiarash Shamsi, Esmaielzadeh Koosha Khorasani, Javad Mohammad Shayegan
Abstract: Today’s world is struggling with the COVID-19 pandemic, as one of the greatest challenges of the 21st century. During the lockdown caused by this disease, many financial losses have been inflicted on people and all industries. One of the fastest ways to save these industries from the COVID-19 is to provide a reliable solution for people’s health assessment. In this article, blockchain technology is used to propose a model which provides and validates the health certificates for people who travel or present in society. For this purpose, we take advantage of blockchain features in protecting people’s privacy. Since a variety of antibody and human health proving tests against the virus are developing, this study tries simultaneously to design an integrated and secure system to meet the authenticity and accuracy of different people’s health certificates for the companies requiring these certifications. In this system, on the one hand, there are qualified laboratories that are responsible for performing standard testing and also providing results to the system controller. Finally, people are considered as the end-user of the system. To provide test information for the entities, the mechanism of KYC tokens will be used based on the Stellar private blockchain network. In this mechanism, the user will buy a certain amount of KYC tokens from the system controller. These tokens are charged in the user’s wallet, and the user can send these tokens from his wallet to any destination company, to exchange the encrypted health certificate information. Finally, considering the appropriate platform provided by blockchain technology and the requirement of a reliable and accurate solution for issuing health certificates during the Covid-19 pandemic or any other disease, this article offers a solution to meet the requirements.
DCDChain: A Credible Architecture of Digital Copyright Detection Based on Blockchain
Authors: Zhili Chen, Yuting Wang, Tianjiao Ni, Hong Zhong
Abstract: Copyright detection is an effective method to prevent piracy. However, untrustworthy detection parties may lead to falsified detection results. Due to its credibility and tamper resistance, blockchain has been applied to copyright protection. Previous works mainly utilized blockchain for reliable copyright information storage or copyrighted digital media trading. As far as we know, the problem of credible copyright detection has not been addressed. In this paper, we propose a credible copyright detection architecture based on the blockchain, called DCDChain. In this architecture, the detection agency first detects copyrights off the chain, then uploads the detection records to the blockchain. Since data on the blockchain are publicly accessible, media providers can verify the correctness of the copyright detection, and appeal to a smart contract if there is any dissent. The smart contract then arbitrates the disputes by verifying the correctness of detection on the chain. The detect-verify-and-arbitrate mechanism guarantees the credibility of copyright detection. Privacy and security analysis and experimental simulations show that the digital copyright detection architecture is reliable, secure and efficient.
Financial
Multiscale characteristics of the emerging global cryptocurrency market
Authors: Marcin Wątorek, Stanisław Drożdż, Jarosław Kwapień, Ludovico Minati, Paweł Oświęcimka, Marek Stanuszek
Abstract: The review introduces the history of cryptocurrencies, offering a description of the blockchain technology behind them. Differences between cryptocurrencies and the exchanges on which they are traded have been shown. The central part surveys the analysis of cryptocurrency price changes on various platforms. The statistical properties of the fluctuations in the cryptocurrency market have been compared to the traditional markets. With the help of the latest statistical physics methods the non-linear correlations and multiscale characteristics of the cryptocurrency market are analyzed. In the last part the co-evolution of the correlation structure among the 100 cryptocurrencies having the largest capitalization is retraced. The detailed topology of cryptocurrency network on the Binance platform from bitcoin perspective is also considered. Finally, an interesting observation on the Covid-19 pandemic impact on the cryptocurrency market is presented and discussed: recently we have witnessed a “phase transition” of the cryptocurrencies from being a hedge opportunity for the investors fleeing the traditional markets to become a part of the global market that is substantially coupled to the traditional financial instruments like the currencies, stocks, and commodities. The main contribution is an extensive demonstration that structural self-organization in the cryptocurrency markets has caused the same to attain complexity characteristics that are nearly indistinguishable from the Forex market at the level of individual time-series. However, the cross-correlations between the exchange rates on cryptocurrency platforms differ from it. The cryptocurrency market is less synchronized and the information flows more slowly, which results in more frequent arbitrage opportunities. The methodology used in the review allows the latter to be detected, and lead-lag relationships to be discovered.
Bitcoin Trading is Irrational! An Analysis of the Disposition Effect in Bitcoin
Authors: E. Jürgen Schatzmann, Bernhard Haslhofer
Abstract: Investors tend to sell their winning investments and hold onto their losers. This phenomenon, known as the \emph{disposition effect} in the field of behavioural finance, is well-known and its prevalence has been shown in a number of existing markets. But what about new atypical markets like cryptocurrencies? Do investors act as irrationally as in traditional markets? One might suspect this and hypothesise that cryptocurrency sells occur more frequently in positive market conditions and less frequently in negative market conditions. However, there is still no empirical evidence to support this. In this paper, we expand on existing research and empirically investigate the prevalence of the disposition effect in Bitcoin by testing this hypothesis. Our results show that investors are indeed subject to the disposition effect, tending to sell their winning positions too soon and holding on to their losing position for too long. This effect is very prominently evident from the boom and bust year 2017 onwards, confirmed via most of the applied technical indicators. In this study, we show that Bitcoin traders act just as irrationally as traders in other, more established markets.
Cryptocurrency portfolio optimization with multivariate normal tempered stable processes and Foster-Hart risk
Authors: Tetsuo Kurosaki, Shin Young Kim
Abstract: We study portfolio optimization of four major cryptocurrencies. Our time series model is a generalized autoregressive conditional heteroscedasticity (GARCH) model with multivariate normal tempered stable (MNTS) distributed residuals used to capture the non-Gaussian cryptocurrency return dynamics. Based on the time series model, we optimize the portfolio in terms of Foster-Hart risk. Those sophisticated techniques are not yet documented in the context of cryptocurrency. Statistical tests suggest that the MNTS distributed GARCH model fits better with cryptocurrency returns than the competing GARCH-type models. We find that Foster-Hart optimization yields a more profitable portfolio with better risk-return balance than the prevailing approach.
A Horserace of Volatility Models for Cryptocurrency: Evidence from Bitcoin Spot and Option Markets
Authors: Yeguang Chi, Wenyan Hao
Abstract: We test various volatility models using the Bitcoin spot price series. Our models include HIST, EMA ARCH, GARCH, and EGARCH, models. Both of our in-sample-fit and out-of-sample-forecast results suggest that GARCH and EGARCH models perform much better than other models. Moreover, the EGARCH model’s asymmetric term is positive and insignificant, which suggests that Bitcoin prices lack the asymmetric volatility response to past returns. Finally, we formulate an option trading strategy by exploiting the volatility spread between the GARCH volatility forecast and the option’s implied volatility. We show that a simple volatility-spread trading strategy with delta-hedging can yield robust profits.
Internet of Things (IoT)
Towards Decentralized IoT Updates Delivery Leveraging Blockchain and Zero-Knowledge Proofs
Authors: Edoardo Puggioni, Arash Shaghaghi, Robin Doss, S. Salil Kanhere
Abstract: We propose CrowdPatching, a blockchain-based decentralized protocol, allowing Internet of Things (IoT) manufacturers to delegate the delivery of software updates to self-interested distributors in exchange for cryptocurrency. Manufacturers announce updates by deploying a smart contract (SC), which in turn will issue cryptocurrency payments to any distributor who provides an unforgeable proof-of-delivery. The latter is provided by IoT devices authorizing the SC to issue payment to a distributor when the required conditions are met. These conditions include the requirement for a distributor to generate a zero-knowledge proof, generated with a novel proving system called zk-SNARKs. Compared with related work, CrowdPatching protocol offers three main advantages. First, the number of distributors can scale indefinitely by enabling the addition of new distributors at any time after the initial distribution by manufacturers (i.e., redistribution among the distributor network). The latter is not possible in existing protocols and is not account for. Secondly, we leverage the recent common integration of gateway or Hub in IoT deployments in our protocol to make CrowdPatching feasible even for the more constraint IoT devices. Thirdly, the trustworthiness of distributors is considered in our protocol, rewarding the honest distributors’ engagements. We provide both informal and formal security analysis of CrowdPatching using Tamarin Prover.
Trustworthy Digital Twins in the Industrial Internet of Things with Blockchain
Authors: Sabah Suhail, Rasheed Hussain, Raja Jurdak, Seon Choong Hong
Abstract: Industrial processes rely on sensory data for critical decision-making processes. Extracting actionable insights from the collected data calls for an infrastructure that can ensure the trustworthiness of data. To this end, we envision a blockchain-based framework for the Industrial Internet of Things (IIoT) to address the issues of data management and security. Once the data collected from trustworthy sources are recorded in the blockchain, product lifecycle events can be fed into data-driven systems for process monitoring, diagnostics, and optimized control. In this regard, we leverage Digital Twins (DTs) that can draw intelligent conclusions from data by identifying the faults and recommending precautionary measures ahead of critical events. Furthermore, we discuss the integration of DTs and blockchain to target key challenges of disparate data repositories, untrustworthy data dissemination, and fault diagnosis. Finally, we identify outstanding challenges faced by the IIoT and future research directions while leveraging blockchain and DTs.
Proof of Work (PoW) alternatives
PoSAT: Proof-of-Work Availability andUnpredictability, without the Work
Authors: Soubhik Deb, Sreeram Kannan, David Tse
Abstract: An important feature of Proof-of-Work (PoW) blockchains is full dynamic availability, allowing miners to go online and offline while requiring only 50% of the online miners to be honest. Existing Proof-of-stake (PoS), Proof-of-Space and related protocols are able to achieve this property only partially, either putting the additional assumption that adversary nodes to be online from the beginning and no new adversary nodes come online afterwards, or use additional trust assumptions for newly joining nodes.We propose a new PoS protocol PoSAT which can provably achieve dynamic availability fully without any additional assumptions. The protocol is based on the longest chain and uses a Verifiable Delay Function for the block proposal lottery to provide an arrow of time. The security analysis of the protocol draws on the recently proposed technique of Nakamoto blocks as well as the theory of branching random walks. An additional feature of PoSAT is the complete unpredictability of who will get to propose a block next, even by the winner itself. This unpredictability is at the same level of PoW protocols, and is stronger than that of existing PoS protocols using Verifiable Random Functions.
Multi-Shard Private Transactions for Permissioned Blockchains
Authors: Elli Androulaki, Angelo Caro De, Kaoutar Elkhiyaoui, Christian Gorenflo, Alessandro Sorniotti, Marko Vukolic
Abstract: Traditionally, blockchain systems involve sharing transaction information across all blockchain network participants. Clearly, this introduces barriers to the adoption of the technology by the enterprise world, where preserving the privacy of the business data is a necessity. Previous efforts to bring privacy and blockchains together either still leak partial information, are restricted in their functionality or use costly mechanisms like zk-SNARKs. In this paper, we propose the Multi-Shard Private Transaction (MSPT) protocol, a novel privacy-preserving protocol for permissioned blockchains, which relies only on simple cryptographic primitives and targeted dissemination of information to achieve atomicity and high performances.
Smart contracts
Towards Cross-Blockchain Smart Contracts
Authors: Markus Nissl, Emanuel Sallinger, Stefan Schulte, Michael Borkowski
Abstract: In recent years, manifold blockchain protocols have been proposed by researchers and industrial companies alike. This has led to a very heterogeneous blockchain landscape. Accordingly, it would be desirable if blockchains could interact with each other. However, current blockchain technologies offer only limited support for interoperability, thus preventing tokens or smart contracts from leaving the scope of a particular blockchain. As a first step towards a solution for cross-chain smart contract interactions, we introduce a framework which allows to invoke a smart contract from another blockchain. We offer support for continuing a smart contract after receiving a result from a different blockchain, and for calling smart contracts recursively across blockchains. We provide a reference implementation for Ethereum-based blockchains using Solidity and evaluate the performance regarding time and cost overheads.
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