Symbolic execution is a popular analysis technique used for finding bugs in Ethereum smart contracts. However, symbolic execution is computationally expensive. Furthermore, during the development of smart contracts, analysis is started from scratch for each new version of the software, recomputing many redundant results. Many approaches exist for the optimisation of symbolic execution, one of which is the use of symbolic summaries. In this thesis, we design a technique which efficiently permits the re-use of symbolic summaries between analyses, allowing for incremental symbolic execution for smart contracts. In particular, the technique aims to permit the re-use of summaries for code with syntactic changes.
First, we analyse the changes which occur in smart contracts for the design and evaluation of the summary checking approach. We formulate a set of three algorithms that use program normalisation and dataflow analysis to deal with the identified change types. We evaluate the performance of our summary checking approach through three benchmarks, focussing on particular change types, real-world scenarios, and compiler introduced changes.
The results show that this technique can be applied effectively in real-world scenarios, allowing for the re-use of, on average, 81\% of symbolic summaries. Furthermore, the methods are particularly effective for program changes resulting from changes in the compiler, reaching a summary re-use rate of 98\%. Finally, in our experiments, summary validation requires an order of magnitude less time than the re-generation of the summaries which remain valid between program versions.
In conclusion, the proposed normalisation based summary checking approach is an effective method for incremental symbolic execution by allowing the re-use of symbolic summaries.
Since the birth of Blockchain technology in 2008, it has been widely implemented in areas of finance, most notably as a cryptocurrency which now has real-world monetary value. The rise of blockchain can be attributed to its unique characteristics: being trust-less, immutable and decentralized. There are companies who adopt private blockchains in general. However, with the emergence of special products such as Infrastructure as a Service that ease blockchain implementation issues, the public blockchains are steadily garnering interests not just from companies but from aspiring blockchain developers as well. \nThis project will develop a mobile application using Ethereum, an open-source and public blockchain platform that enables developers to create decentralized applications with it along with Android Studio to create the application for mobile usage. Then, security testing is performed on the application. Using the observations from the tests, we will be able to identify threats that the blockchain environment can and cannot prevent.
The world experienced unprecedented growth in international trade in the past few decades. In this resulting environment of global competition, several new companies have spawned and are spawning. Sellers are often under immense pressure by the market players to accept open-account trade terms, shipping goods before receiving payment, leaving them exposed to increased risk. This creates working capital challenges for firms, especially small and medium enterprises. To mitigate this supply chain risk, several supplier-led and buyer-led supply chain finance solutions are facilitated by banks and financial technology companies. However, because of the new Basel III regulation framework for banks and several other Supply Chain Finance (SCF) adoption barriers, like fraudulent activities, many firms are unable to reap SCF’s full benefits. This study explains various SCF instruments, the key drivers in their growth and their adoption barriers. This study then focuses on the novel blockchain technology and smart contracts by delving deep into their history, components, limitations, risks and use cases. Using the knowledge gathered in the process, a proof-of-concept blockchain and smart contract is developed using the Ethereum platform, which can facilitate normal business, purchase order finance, reverse factoring and reverse securitization. To test the smart contract, four use cases for each SCF instrument mentioned are demonstrated. A JavaScript-based unit test is done to test the smart contract’s correct deployment and onboarding of actors along with their business and financing interactions – access controls to business documents, reverting malicious transactions and correct fund transfer. As a result of various assumptions taken in the development process, the smart contract works only as a basic proof-of-concept and lacks robustness on the ground of scalability and security. As a result, a future model is laid out which will use various software and hardware oracles for autonomous operations while using a complex system of a storage contract, a permanent contract which stores all the data, and logic contract, upgradable contract which can be changed any number of times, with a proxy contract making delegated “function” calls to logic contract to reduce the gas usage due to external function calls.
The field of post-quantum cryptography studies cryptographic systems that are secure against an adversary in possession of a quantum computer. In 2017, the National Institute of Standards and Technology (NIST) initiated a process to standardize quantum-resistant public-key cryptographic algorithms (NIST PQC Project). In this thesis we analyze the performance and security of the Bit-Flipping Key Encapsulation Mechanism (BIKE) -- one of the candidates in the NIST PQC project which advanced to the second round of the standardization process. BIKE is a code-based cryptographic system featuring three different variants of the protocol. In the first round of the NIST PQC project BIKE offered security only against chosen-plaintext attacks (CPA). In the second round, BIKE introduced three new variants that are claimed to be secure also against chosen-ciphertext attacks (CCA). Firstly, we build a secure implementation of the CCA protocol and show that its performance characteristics are only negligibly worse than the CPA variant. In the key decapsulation phase of the protocol BIKE uses a decoding algorithm which fails with some probability, called the Decoding Failure Rate (DFR). We analyze the DFR of two decoders used in BIKE, Back-Flip and Black-Gray, and propose a new decoder, called Black-Gray-Flip, that achieves the same DFR as the two previously used decoders while being almost twice as fast. Finally, we propose an algorithm for inversion of binary polynomials in a polynomial ring used in BIKE-2, the second variant of BIKE. Our implementation of the inversion significantly outperforms previously used algorithms. With this and the fact that the bandwidth requirement for BIKE-2 is the smallest among the three variants, BIKE-2 is positioned as the preferable variant of BIKE. The second part of this thesis studies the Legendre pseudorandom function (PRF) which is proposed to be used in the context of blockchains. We present a new algorithm for cryptanalysis of the Legendre PRF. The complexity of our algorithm is lower than the previous best known algorithm. Moreover, we show the results of breaking three Legendre PRF challenges posed by the Ethereum foundation. The most difficult challenge that we solved set the new record which is not broken so far.
Blockchain technology makes use of a centralized, peer-to-peer (P2P) network of databases, also called nodes, to validate and record digital transactions between individual users located anywhere across the globe. These transactions often take place through the exchange of cryptocurrencies such as bitcoins, Ethereum, and Ripple, etc. The security and transparency that is inherently present in digital transactions place blockchain technology in high demand across various industrial applications. Each node updates its database in real-time as and when transactions occur. The transaction gets authorized only when a majority of the nodes in the network validate the transaction. Once the verification is complete, a block, consisting of hash and keys, is generated for each new transaction and is linked to previous transactions in every database. Every node updates its database with the new block. A hacker would have to break down every node in the system to commit fraud. Blockchain could play a major role in maintaining the cyber security of digital transactions in the future.
Central bank digital currencies have been on the rise for the past few years, especially after the emergence of cryptocurrencies like Bitcoin, Ethereum, Ripple and others. Leading central banks like the People's Bank of China and Riksbanken (Swedish Central Bank), and some of the other central banks around the world have been looking to develop and test central bank digital currencies around the world. Nonetheless, the main question that we need to answer is if the cryptocurrencies or central bank digital currencies (CDBC) will become the main form of money in the future or will these currencies harmoniously co-exist within the economy paradigm? This paper applies monetary and political economy concepts to discuss how a potential central bank digital currency can be developed and how it would compete with cryptocurrencies. In conclusion, however, the introduction of a central bank digital currency will reduce the monetary policies issues rather than create new issues and this paper will explain how this can be achieved.
Київський національний економічний університет імені Вадима Гетьмана, Михайло ОРЄХОВ, Т.В. Орєхова, Донецький національний університет імені Василя Стуса
The paper analyzes the role of digital currencies in the global financial system, the peculiarities of their use. The paper pays attention to the characteristics of the historical preconditions for the emergence of electronic payments and, as a consequence, digital currencies. The paper analyzes the features of the emergence and functioning of major global cryptocurrencies - Bitcoin, Ripple and Ethereum. The advantages of cryptocurrencies, the authors of the study include unlimited opportunities for transactions, no borders, transaction speed. Among the disadvantages of cryptocurrencies is the lack of a proper level of knowledge, which leads to the spread of fraud. The paper presents the volume and share of bitcoin trade in different markets during the period from January 2013 to January 2018. The results of the study allow us to conclude that the modern cryptocurrency market, despite the fact that the evolution of electronic money is in its infancy, and cash is still the most important form of payment for retail transactions, is highly competitive and fragmented.
Jan 1, 2020·Proceedings of the ... Annual Hawaii International Conference on System Sciences/Proceedings of the Annual Hawaii International Conference on System Sciences
Daniel Miehle, Andreas Pfurtscheller, Bernd Bruegge
Current Vehicle-to-Vehicle solutions cannot ensure the authenticity of safety-critical vehicle and traffic data. Moreover, they do not allow malicious vehicles to be detected and eliminated. However, this is becoming mandatory, as more and more vehicles are on the road and communicating with each other. We propose a system called Starling, which focuses on trusted coordinated obstacle mapping using blockchain technology and a distributed database. Starling enables vehicles to share detected obstacles with other vehicles in a secure and verifiable manner, thus improving road safety. It ensures that data was not manipulated, changed, or deleted and is based on an open protocol so that vehicles can exchange data regardless of their manufacturer. In a case study, we demonstrate how a consensus is reached among vehicles and conduct a comprehensive evaluation of the Starling system using Ethereum and the InterPlanetary File System.
The use of digital documents is exploding around the world due to the improvement of productivity and the convenience of access and backup of data.Usually, digital documents are managed by a document management system (DMS) which provides access control of the documents with access permission (e.g., password or account).However, when a user who has permission for the documents can directly access the digital document, it can occur a serious security problem.For example, when a malicious attacker gets access permission of a digital document, the document is able to be leaked.In addition, when a user who has authority behaves maliciously for his own benefit, the digital document can be easily falsified by the user.To handle these issues, we propose a new digital document management system for the security of digital documents which distributes the access permissions of the digital document.The proposed system encrypts a digital document with a key and stores the encrypted document into Interplanetary File System(IPFS).In addition, to distribute access permission of the digital document, it manages the key via Shamir's secret sharing scheme and blockchain.We implement our proposed system using Golang on Linux and evaluate the system on local IPFS and Ethereum testnet.The experimental results show that the proposed system provides high security of the digital document with minor performance overhead compared with the existing system.
In recent years, cryptocurrencies implemented on top of Blockchains became very popular, with Bitcoin as the most prominent example. However, novel Blockchain-based platforms such as Ethereum also support distributed applications beyond cryptocurrencies through so-called smart contracts. Technically, smart contracts are programs, whose code and execution state is stored in the Blockchain, inherently featuring the ability to transfer (electronic) money during their execution. In this Bachelor thesis, we investigate how smart contracts can be used to implement a distributed crowdsensing application for tracking mobile objects by a crowd of privately owned mobile devices. Such a system could be used, for instance, to nd lost or stolen objects, such as keys, vehicles (cars, bicycles, . . . ), or pets tagged with short-range radio transmitters implemented using readily available Bluetooth or RFID technology. These objects can then be detected by smartphones of private users in the vicinity of the object, effectively implementing a huge sensor network covering many parts of the world without any upfront investments by a central entity. Although highly attractive, implementing a crowdsensing application on top of a Blockchain platform such as Ethereum comes with several challenges. First of all, users need incentives to participate in searching for mobile objects. A natural incentive is a monetary reward that participants automatically receive through the smart contract when reporting sightings (timestamped positions) of wanted objects. However, this directly brings up the problem of malicious participants (attackers) who try to get the reward without actually executing the work of searching for the object by simply reporting fake positions. Therefore, one major goal of this Bachelor thesis is to counter such attacks by proposing effective counter-measures, and implementing and evaluating them for the Ethereum platform. In detail, we propose a basic reputation-based approach for detecting fake positions which judges each sighting made by a mobile devices according to the reputation of that device, implemented by a smart contract. Furthermore, advanced attacks are identified compromising the basic reputation-based approach and effective counter-measures to these advanced attacks are proposed. Identified advanced attacks include reputation farming, where the attacker tries to aggregate reputation first before launching the attack, and the so-called copycat attack, where the attacker simply copies already submitted valid sightings form honest participants, making his fake positions indistinguishable from valid positions. Our evaluations analyses the monetary cost of executing smart contracts with and without our security mechanisms. The results show that the overhead included by our reputation-based approach is at maximum 45% of the cost of a smart contract without implemented security mechanisms.
Blockchain is considered an emerging technology, having aroused the interest of researchers \nand industries on the world stage. After the success of this technology in the financial market \nwith virtual currencies (such as Bitcoin and Litecoin), blockchain starts to be used by different \ndomains, such as government and education, as it provides a reliable, scalable and immutable \ndistributed environment for the realization and storage of transactions on a network. Smart \ncontracts are one of the features of the Ethereum blockchain, which has the ability to run a \nprogramming model for applications distributed in untrusted environments. These contracts \nreside on the blockchain and enable process automation in several stages. Smart contracts have \nbecome one of the most sought-after technologies due to the high customization they add to \ntransactions, allowing to seek blockchain-based solutions to problems in industry and academia. \nHigher education is a system with several challenges that can be solved with the adoption of \nthis technology. Protecting data transactions involving student degrees is one of the challenges \nconsidered by educational institutions. Thus, this work presents an architecture proposal based \non blockchain technology to store and consult data from diplomas issued by higher education \ninstitutions. Through this architecture, a new approach for the validation of diploma data with \nthis emerging technology was evaluated. As a proof of concept, a prototype of the environment \nwas implemented using smart contracts based on the Ethereum platform. After implementation, \nan evaluation was carried out with specialists in the management of diplomas and an analysis \nof the performance of the transactions carried out in the prototype was carried out. In view of \nthe results obtained, the proposal proved to be adequate to the process of storing and consulting \ndiploma data.
PurposeThis study presents research on the awareness and aspirations of millennials towards different investment asset classes with a special focus on cryptocurrencies. Cryptocurrencies are technology dependent digital money systems which have created a buzz in the financial markets in a very short period of time. Digital currencies like Bitcoin, Ethereum, Ripple, Bitcoin Cash, etc., are considered as a new investment asset category that seems to be associated with high risk and return. There are a number of advantages and disadvantages associated with them, but countries, like Japan and the US, have accepted them for some types of transaction, however, India, one of the five largest emerging economies of 2018, has still not accepted them. In spite of government and regulatory inertia towards cryptocurrencies, we have found that awareness and aspiration to invest in this category among millennials is increasing. The objective of this paper is to understand the investment attitudes of millennial investors towards the desire to invest in cryptocurrencies given the disposition of this generation towards the digital world and technologies.Study designThis study is conducted in Mumbai to assess the interest levels in this category especially among the millennial generation. This is a primary research study and data has been collected via face-to-face interviews, and a structured questionnaire, with suitable open-ended questions, involving 100 millennial retail investors in Mumbai, and a random sampling method. The participants were aware of the risk level of the selected financial products. Descriptive statistics and advance analysis techniques, such as correlation, factor and multiple regression analysis, were used as tools to describe relationships in the investment category, to decipher the pattern of the decision-making process among millennials with respect to investment in different categories of financial products.FindingsThe underlying motivation for any financial investment is growth and appreciation of value at an expected rate of return. It is this motivation that needs to be managed by any financial planner, and this is the foundational finding of our research with respect to cryptocurrencies. This study provides information to regulators, recommending adoption of cryptocurrencies within a regulated structure in India.LimitationsThis study has been conducted in Mumbai only.ImplicationsThe fundamental objective of any investment is a positive return and that positive return has to be well managed by governments, regulators and financial marketers.ContributionThis study presents new evidence given the changes that have occurred recently in the financial markets and also highlights the variables that could be determining factors of risk appetite/tolerance for millennial retail investors. It clearly highlights that financial literacy and maturity of millennial investors will drive interest levels in a particular asset class. Prior knowledge about the level of diffusion and adoption of cryptocurrencies as a new asset among Indian millennials will help in creating a relevant policy framework. This will also help in creating a society-safety network among rising digital communities. This is a potentially transparent technological solution that can facilitate many financial solutions such as investments, remittances, and innovative ways to build financial inclusion in society.
The purpose of this thesis is to study the predictability of cryptocurrency returns by investor attention, the interconnections of the cryptocurrency market, and what causes attention to cryptocurrencies. This is done by examining Bitcoin, Ethereum and Ripple which are the three biggest cryptocurrencies by market capitalization in January 2020. The dataset is constructed from weekly returns, weekly changes in investor attention measured by Google trend data and weekly changes in average weekly trading volume between years 2016 and 2019. The empirical analysis is conducted by performing OLS regressions, vector autoregressions and Granger causality tests. Additional robust tests are conducted by dividing the sample in pre-bubble and post-bubble samples adding all of the investor attention proxies to individual Cryptocurrency regressions. The results suggest that the market phase for a cryptocurrency affects the predictability of returns as the statistically significant positive relationship between investor attention disappears in the post-bubble sample for Bitcoin and Ethereum but endures for Ripple in both samples. This provides more evidence for the earlier findings that cryptocurrencies become more efficient as the market matures. The interconnections of the cryptocurrency market are shown to exist as the returns of Bitcoin drive investor attention to Ripple which is shown to be a significant predictor for all of the three cryptocurrencies in the whole sample. The spillover effect is shown to take time confirming earlier findings and unfolding the herding effect via investor attention in cryptocurrencies. Additionally, investor attention is shown to be caused by earlier returns for the cryptocurrency as well as the returns of Bitcoin. These results explain the interconnections of cryptocurrencies, the changing market dynamics in the cryptocurrency market, and the predictability of cryptocurrency returns by investor attention.
Afees A. Salisu, Ahamuefula E. Ogbonna, Tirimisiyu F. Oloko
This study examines the effect of a pandemic-induced uncertainty on cryptocurrencies (specifically, Bitcoin, Ethereum and Ripple). It employs a predictive model by Westerlund and Narayan (2012, 2015) to examine the predictability of a pandemic-induced uncertainty as a predictor, as well as the forecast performance of our predictive model for cryptocurrency returns. We examine the role of asymmetry in uncertainty and the sensitivity of our results to alternative measures of uncertainty due to pandemics, using the recently developed Global Fear Index (GFI) by Salisu and Akanni (2020). Our results indicate that cryptocurrencies could act as hedge against uncertainty due to pandemics, albeit with reduced hedging effectiveness in the COVID-19 period. Accounting for asymmetry is found to improve the predictability and forecast performance of the model, which indicates that failure to account for asymmetry in modeling the effect of a pandemic-induced uncertainty on cryptocurrency may lead to incorrect conclusion. The results seem to be sensitive to the choice of measure of pandemic-induced uncertainty.
Mohamed Inthias Ali S, Jashwanth, N. Diwakar, A. V. Lalitha
BLOCKCHAIN BASED PROPERTY REGISTRATION USING CONCEPT OF SMART CONTRACT is a “simple Dapp based on the ethereum blockchain. It can replace the current approach. Here the land owner(Buyer) registers the land details along with the land value by providing digitalised documents. Only a registrar or government authority who is uncharged as the admin can do the registration process. Lands coming under a area (eg., a village) can register to the system only through the admin(registrar) assigned to that area. The smart contract has been created in a way that the owner has to transfer his full asset(data or documents) to the buyer and no partial transaction of the asset is allowed. Even though the registration process requires a government authority, the entire process is transparent and the transaction happens between the the two clients without any intermediaries