Consensus: Proof of Work, Proof of Stake and Structural Alternatives

NIcola Dimitri

in Enabling the Internet of Value, (Tasca P.-Vadgama N. eds) forthcoming Springer Verlag, (2021)

Abstract

URL:

Further information:

Monetary Dynamics with “Proof of Stake”

Nicolas Dimitri

Frontiers in Blockchain doi: 10.3389/fbloc.2021.443966 (2021)

Abstract

In recent years blockchain consensus mechanisms based on Proof of Stake gained increasing attention as an alternative to Proof of Work, which requires high energy consumption. In its original version Proof of Stake hinges on the idea that, for a user, the likelihood to confirm the next block is positively related to the amount of currency units held in the wallet, and possibly also on the time length which the money has been unspent for. In a simple framework with risk neutral users we provide some early insights on the monetary equilibrium of Proof of Stake based platforms. In particular, we find that the aggregate demand and supply of currency may not coincide, which implies that users could hold suboptimal quantities of the currency. Furthermore, we also discuss how symmetric stationary states of the system could be implausible. As a consequence, a long run uniform distribution of money would seem unlikely unless appropriate measures are introduced.

Transaction Fees, Block Size Limit and Auctions in Bitcoin

Nicola Dimitri

Ledger, 4, 68-81, (2019)

Abstract

Confirmation of Bitcoin transactions is executed in blocks, which are then stored in the Blockchain. As compared to the number of transactions in the mempool, the set of transactions which are verified but not yet confirmed, available space for inclusion in a block is typically limited. For this reason, successful miners can only process a subset of such transactions, and users compete with each other to enter the next block by offering confirmation fees. Assuming that successful miners pursue revenue maximization, they will include in the block those mempool transactions that maximize earnings from related fees. In the paper we model transaction fees as a Nash Equilibrium outcome of an auction game with complete information. In the game the successful miner acts as an auctioneer selling block space, and users bid for shares of such space to confirm their transactions. Moreover, based on expected fees we also discuss what the optimal, revenue maximizing, block size limit should be for the successful miner. Consistently with the intuition, the optimal block size limit resolves the trade-off between including additional transactions (which possibly lower the unit fees collected) and keeping the block capacity limited (with, however, higher unit fees).

The Blockchain Technology; Some Theory and Applications

Nicola Dimitri

Maastricht School of Management Working Paper, 2017/3 (2017)

Abstract

In the paper we analyse the current EU public procurement legislation on innovative solutions from an economic perspective. In particular, for contracting authorities interested in procuring products which are not yet in the market we identify two main options, based on whether or not they decide to unbundle the procurement of R&D services from that of the final product. Taking the point of view of both the competing firms and the contracting authorities we discuss economic advatanges and limitations of the two options. We specifically focus on the R&D stage arguing that to develop an innovative solution selected firms may compete, but also collaborate.

Bitcoin Mining as a Contest

Nicola Dimitri

Ledger, 2, 31-37 (2017)

Abstract

This paper presents a simple game theoretic framework, assuming complete
information, to model Bitcoin mining activity. It does so by formalizing the activity as an
all-pay contest: a competition where participants contend with each other to win a prize by
investing in computational power, and victory is probabilistic. With at least two active
miners, the unique pure strategy Nash equilibrium of the game suggests the following
interesting insights on the motivation for being a miner: while the optimal amount of
energy consumption depends also on the reward for solving the puzzle, as long as the
reward is positive the decision to be an active miner depends only on the mining costs.
Moreover, the intrinsic structure of the mining activity seems to prevent the formation of a
monopoly, because in an equilibrium with two miners, both of them will have positive
expected profits for any level of the opponent’s costs. A monopoly could only form if the
rate of return on investment were higher outside bitcoin.

Efficiency and Equilibrium in the EMAIL Game; The General Case

Nicola Dimitri

Theoretical Computer Science, 314, 335-349, (2003).

Abstract

In the Email Game (Amer. Econom. Rev. 79 (1989) 385) noisy information channels may prevent risky-efficient coordination, even when the game is almost common knowledge. In this paper, we show that this is the case whenever message failure probabilities are not sufficiently different. Quite intuitively, the extent of the difference is governed by the game payoffs, and in particular by the mixed Nash Equilibrium strategy of one of the two games to be played. This is because, conditionally to having observed one’s type, a player’s beliefs on the opponent’s choices are governed by the reliability of communication channels.

Correlated Communication

Dimitri- Basili-Gilboa eds

Cognitive Processes and Economic Behavior

Abstract

By using an iterative notion of common knowledge, Rubinstein drew attention to the (possibly puzzling) fact that ‘almost common knowledge’ of a relevant game might not be enough for the efficient, but risky, joint course of actions to be played as a Nash Equilibrium (NE) of the game. Monderer-Samet (1989) argued in support of an alternative notion of approximate common knowledge, viewed as common p-beliefs, when p is sufficiently close to one. With this alternative idea they were able to prove a general result in which the above mentioned action profile could be played, with sufficiently high probability, when players are ‘approximately’ best repliers.

Coordination in an Email Game without “Almost Common Knowledge”

Nicola Dimitri

Journal of Logic, Language, and InformationVol. 12, No. 1 (2003), pp. 1-11 (11 pages)

Abstract

The paper presents a variation of the EMAIL Game, originally proposed by Rubinstein (American Economic Review, 1989), in which coordination of the more rewarding-risky joint course of actions is shown to obtain, even when the relevant game is, at most, “mutual knowledge.” In the example proposed, a mediator is introduced in such a way that two individuals are symmetrically informed, rather than asymmetrically as in Rubinstein, about the game chosen by nature. As long as the message failure probability is sufficiently low, with the upper bound being a function of the game payoffs, conditional beliefs in the opponent’s actions can allow players to choose a more rewarding-risky action. The result suggests that, for efficient coordination to obtain, the length of interactive knowledge on the game, possibly up to “almost common knowledge,” does not seem to be a major conceptual issue and that emphasis should be focused instead on the communication protocol and an appropriate relationship between the reliability of communication channels and the payoffs at stake.

URL:

https://www.jstor.org/stable/40180293

Further information:

NFTs and Copyright: Challenges and Opportunities

Pınar Çağlayan Aksoy & Zehra Özkan Üner

2021, awaiting publication.

Abstract

URL:

Further information:

The Formation and Validity of Smart Contracts

Pınar Çağlayan Aksoy

January, 2021, Istanbul. (Book: in Turkish)  

Abstract

URL:

Further information:

AI as Agents: Agency Law, Artificial Intelligence and Private Law: Global Perspectives

Pınar Çağlayan Aksoy

2021 (ed. Larry DiMatteo, Cristina Poncibo, Pietro Sirena, Michel Cannarsa), Cambridge University Press, awaiting publication.

Abstract

URL:

Further information:

The evolving liaisons between the transaction networks of Bitcoin and its price dynamics

Bovet A., Campajola C., Mottes F., Restocchi V., Vallarano N., Squartini T., Tessone C.J.

working paper (2019)

Abstract

Cryptocurrencies are distributed systems that allow exchanges of native tokens among participants, or the exchange of such tokens for fiat currencies in markets external to these public ledgers. The availability of their complete historical bookkeeping opens up the possibility of understanding the relationship between aggregated users’ behaviour and the cryptocurrency pricing in exchange markets. This paper analyses the properties of the transaction network of Bitcoin. We consider four different representations of it, over a period of nine years since the Bitcoin creation and involving 16 million users and 283 million transactions. By analysing these networks, we show the existence of causal relationships between Bitcoin price movements and changes of its transaction network topology. Our results reveal the interplay between structural quantities, indicative of the collective behaviour of Bitcoin users, and price movements, showing that, during price drops, the system is characterised by a larger heterogeneity of nodes activity.

URL:

arXiv

Further information:

Unveiling the relation between herding and liquidity with trader lead-lag networks

Campajola C., Lillo F., Tantari D

Quantitative Finance, 2020

Abstract

We propose a method to infer lead-lag networks of traders from the observation of their trade record as well as to reconstruct their state of supply and demand when they do not trade. The method relies on the Kinetic Ising model to describe how information propagates among traders, assigning a positive or negative ‘opinion’ to all agents about whether the traded asset price will go up or down. This opinion is reflected by their trading behavior, but whenever the trader is not active in a given time window, a missing value will arise. Using a recently developed inference algorithm, we are able to reconstruct a lead-lag network and to estimate the unobserved opinions, giving a clearer picture about the state of supply and demand in the market at all times. We apply our method to a dataset of clients of a major dealer in the Foreign Exchange market at the 5 minute time scale. We identify leading players in the market and define a herding measure based on the observed and inferred opinions. We show the causal link between herding and liquidity in the inter-dealer market used by dealers to rebalance their inventories.

URL:

Taylor & Francis Online

Further information:

Modelling time-varying interactions in complex systems: the Score Driven Kinetic Ising Model

Campajola C., Di Gangi D., Lillo F., Tantari D

working paper (2020)

Abstract

We introduce a generalization of the Kinetic Ising Model using the score-driven approach, which allows the efficient estimation and filtering of time-varying parameters from time series data. We show that this approach allows to overcome systematic errors in the parameter estimation, and is useful to study complex systems of interacting variables where the strength of the interactions is not constant in time: in particular we propose to quantify the amount of noise in the data and the reliability of forecasts, as well as to discriminate between periods of higher or lower endogeneity in the observed dynamics, namely when interactions are more or less relevant in determining the realization of the observations. We apply our methodology to three different financial settings to showcase some realistic applications, focusing on forecasting high-frequency volatility of stocks, measuring its endogenous component during extreme events in the market, and analysing the strategic behaviour of traders around news releases. We find interesting results on financial systems and, given
the widespread use of Ising models in multiple fields, we believe our approach can be efficiently adapted to a variety of settings, ranging from neuroscience to social sciences and machine learning

URL:

arXiv

Further information:

Blockchain for business: redefining trust

Zavolokina, L., Naef, A.

Smart Insights. Ergon Informatik AG

Abstract

Blockchain has been around for a long time but, as the hype dies down, this security-based technology continues to challenge the business status quo across many organisations and industries, with Gartner predicting full scalability by 2023. So, what does it look like behind the scenes of the technology everyone is talking about?

URL:

Ergon

Further information:

Leitfaden Blockchain in der kantonalen Verwaltung Zürich

Zavolokina, M., Spychiger, F. & Schwabe G.

Kanton Zürich, Staatskanzlei, Digitale Verwaltung und E-Government

Abstract

Die Blockchain-Technologie ist ein aktuelles Thema für die digitale Transformation, da sie das
Potenzial bietet, geschäftsübergreifende Prozesse zu optimieren, Transparenz in Geschäftsabläufen zu erhöhen und eine Vertrauensbasis zwischen den involvierten Parteien zu schaffen. Damit kann die Blockchain-Technologie für verschiedene Branchen und Märkte Mehrwerte generieren. Neben erfolgreichen Anwendungen in Branchen wie Fintech und Vermögensverwaltung steigt
die Relevanz der Blockchain-Technologie in der öffentlichen Verwaltung für Identitäts- und Aktenmanagement, Registereinträge, Vertragsmanagement, Abstimmungen, Zahlungsvorgänge, Unterschriften und weitere Anwendungen.

URL:

Kanton Zürich

Further information:

Designing for Trust in a Blockchain Platform

Zavolokina, L., Zani, N., & Schwabe, G.

IEEE Transactions on Engineering Management (IEEE TEM) Journal

Abstract

Trust is a crucial component for successful transactions regardless of whether they are executed in physical or virtual spaces. Blockchain technology is often discussed in the context of trust and referred to as a trust-free, trustless, or trustworthy technology. However, the question of how the trustworthiness of blockchain platforms should be demonstrated and proven to end users still remains open. While there may be some genuine trust in the blockchain technology itself, on an application level trust in an IT artifact needs to be established. In this article, we examine how trust-supporting design elements may be implemented to foster an end user’s trust in a blockchain platform. We follow the design science paradigm and suggest a practically useful set of design elements that can help designers of blockchain platforms to build more trustworthy systems.

URL:

Zora

Further information:

Potential and Limits of Blockchain Technology for Networked Businesses

Bons., R. W. H., Versendaal, J., Zavolokina, L., & Shi, L

Electronic Markets Journal

Abstract

Blockchains might facilitate and contribute to other disruptive innovations, such as the sharing economy, the circular economy as well as smart grids that help businesses and private households to become independent in their energy provisioning. The challenge for scientists now is to distinguish between the hype and the core value of this phenomenon, to reason about and to reflect on the business potential, including the potential to disrupt trusted business models, but also to address some of the deeper technical foundations such as scalability, accountability, and security. This is the time for re- search to explore descriptive, explanatory and design research questions on Blockchain technology.

URL:

Springer

Further information:

How Can We Reduce Information Asymmetries and Enhance Trust in ‘The Market for Lemons’?

Zavolokina, L., Schlegel, M., & Schwabe, G.

Information Systems and e-Business Management Journal (ISeBM)

Abstract

The used car market is characterized by information asymmetries and mistrust. Blockchain technology promises to resolve these problems using a system which stores data over the life cycle of a vehicle. However, while blockchain technology is strong in preserving the stored information, sense-making of this information is still essential to bring value to end consumers of the system. In this paper, we take an exploratory approach and create a prototype, which is then evaluated in realistic car sale conversations between buyers and sellers. We demonstrate and discuss how the interplay of different design elements of an application, built on top of a blockchain-based platform, helps to reduce information asymmetries and enhance trust. Our findings suggest that though providing more information about a used product (a car) leads to fewer information asymmetries in general, a reputation mechanism and data analysis are both beneficial in improving the situation further. As for trust, such a system enhances trust between buyers and sellers and, in general, makes the overall purchase process more trustworthy. However, to achieve these positive effects, the quality of the stored information should be guaranteed and properly communicated to the end-user.

URL:

ResearchGate

Further information:

Value Creation From a Decentralized Car Ledger

Bauer, I., Zavolokina, L., & Schwabe, G.

Frontiers in Blockchain

Abstract

Blockchain technology is expected to create a variety of new opportunities for businesses. Yet, little is known about how the technology actually enables to create value and how companies will be able to exploit true business value. However, without a clear understanding of the value creation potential from the technology, and corresponding adaption of business practices, the realization of value is doomed to failure. Hence, we contribute to this gap by exploring and explicating the specificities of value creation from blockchain in the ecosystem of a car. In the course of an exploratory case study analysis, over a time period of 2 years, we conducted three iterations of interviews and workshops with industry and blockchain experts from five diverse stakeholder groups. In brief, we provide early evidence that (1) blockchain enables value creation through: Distributed Product Innovation, Shared Operational Efficiency, and Controlled Customer Intimacy. Furthermore, we discuss our learnings for businesses in other domains aiming to leverage value from blockchain technology. We do so, by deriving guidelines for each blockchain value discipline. Furthermore, we give recommendations on how blockchain projects in ecosystems should approach multiple blockchain value potentials.

URL:

Frontiers

Further information:

Management, Governance and Value Creation in a Blockchain Consortium

Zavolokina, L., Ziolkowski, R., Bauer, I., & Schwabe, G.

MIS Quarterly Executive (MISQE) Journal

Abstract

In recent years, an increasing number of blockchain consortia have emerged. However, little is known about how these consortia are developed and what tensions emerge in such collaborations. We describe the evolution of the cardossier blockchain consortium in Switzerland, which is building a system for managing car data and seeking to improve collaboration between players in the car-related ecosystem. From our involvement with the cardossier project, we have gained insights that will be valuable for enterprises considering whether to join a blockchain consortium.

URL:

Zora

Further information:

Is there a market for trusted car data?

Ingrid BauerLiudmila Zavolokina & Gerhard Schwabe 

Electronic Markets volume 30, pages211–225(2020)

Abstract

The used-car trade is characterized by information asymmetries between buyers and sellers leading to uncertainty and distrust, thus causing market inefficiencies. Prior research has shown that blockchain offers a solution: a transparent, trustworthy and verified car history that addresses these issues in the market for ‘lemons’. Yet, whether or not there really is a market for trusted car data remains an open question. In particular, it is unclear if trusted car data increases transparency in the market for lemons and how market participants value increased transparency. Hence, through a market game with 50 participants, we explored the effects of trusted car data on the sales price of the cars, and the relative revenue of buyers and sellers. Additionally, we conducted interviews with the participants to elicit the perceived customer value. The results show that blockchain enables an increase in transparency and creates value for both buyers and sellers.

URL:

Springer

Further information:

Why Should I Trust a Blockchain Platform? Designing for Trust in the Digital Car Dossier

Liudmila Zavolokina, Noah Zani and Gerhard Schwabe

International Conference on Design Science Research in Information Systems and Technology

Abstract

Trust is a crucial component for successful transactions regardless of whether they are executed in physical or virtual spaces. Blockchain technology is often discussed in the context of trust and referred to as a trust-free, trustless, or trustworthy technology. However, the question of how the trustworthiness of blockchain platforms should be demonstrated and proven to end users still remains open. While there may be some genuine trust in the blockchain technology itself, on an application level trust in an IT artifact needs to be established. In this study, we examine how trust-supporting design elements may be implemented to foster an end user’s trust in a blockchain platform. We follow the design science paradigm and suggest a practically useful set of design elements that can help designers of blockchain platforms to build more trustworthy systems.

URL:

Springer

Further information:

Dealers of Peaches and Lemons: How Can Used Car Dealers Use Trusted Car Data to Create Value?

Baumann, J., Zavolokina, L., & Schwabe, G.

Proceedings of the 54th Hawaii International Conference on System Sciences

Abstract

The used car market is full of mistrust and uncertainties. Providing a vehicle history with trusted car data increases market transparency but also threatens the market position of used car dealers. But does a vehicle history also provide opportunities for them? Based on expert interviews, we propose three design principles addressing current problems. The evaluation results of prototypes – which are based on these principles – indicate that they could improve the current market situation by easing data access, increasing the efficiency of sales related processes, and by expanding the competences of used car dealers. This paper is one of only few papers analyzing the current situation of used car dealers in the light of emerging new technologies. It indicates that used car dealers do not necessarily become disintermediated by the provision of trusted car data but rather have opportunities to reinvent themselves.

URL:

ScholarSpace

Further information:

Arbitrage on Markets for Cryptocurrencies

Crépellière, Tommy and Zeisberger, Stefan

Abstract

Recent literature has documented substantial arbitrage opportunities in markets for cryptocurrencies. Given these rather surprising findings, we re-examine the exchange rates of four cryptocurrencies on 21 exchanges with data from October 2018 to June 2019. Our results first provide evidence that price differences exist based on our created arbitrage indices, however, at only a fraction of values reported in previous literature. We then analyze the drivers of these price differences, identifying exchange-specific factors to have the most important role. Based on this, we test actual arbitrage strategies for specific cryptocurrency and fiat currency pairs, finding, in contrast to previous literature, that arbitrage opportunities hardly exist.

URL:

SSRN

Further information:

Improving Investment Decisions with Simulated Experience

Bradbury, Meike and Hens, Thorsten and Zeisberger, Stefan

Abstract

We apply a new and innovative approach to communicating risks associated with financial
products that should support investors in making better investment decisions. In our experiments,
participants are able to gain ”simulated experience” by random sampling of a previously described return
distribution. We find that simulated experience considerably improves participants’ understanding of the
underlying risk-return profile and prompts them to reconsider their investment decisions and to choose
riskier financial products without regretting their higher risk-taking behavior afterwards. This method
of experienced-based learning has high potential for being integrated into real-world applications and
services.

URL:

Zora

Further information:

Cryptographic Primitives in Blockchain Technology: A mathematical introduction

Andreas Bolfing

This book is based on a Master Thesis at the Applied Algebra Group at UZH and the foreword is written by Prof. Dr. Joachim Rosenthal.

Abstract

Many online applications, especially in the financial industries, are running on blockchain technologies in a decentralized manner, without the use of an authoritative entity or a trusted third party. Such systems are only secured by cryptographic protocols and a consensus mechanism. As blockchain-based solutions will continue to revolutionize online applications in a growing digital market in the future, one needs to identify the principal opportunities and potential risks. Hence, it is unavoidable to learn the mathematical and cryptographic procedures behind blockchain technology in order to understand how such systems work and where the weak points are. The book provides an introduction to the mathematical and cryptographic concepts behind blockchain technologies and shows how they are applied in blockchain-based systems. This includes an introduction to the general blockchain technology approaches that are used to build the so-called immutable ledgers, which are based on cryptographic signature schemes. As future quantum computers will break some of the current cryptographic primitive approaches, the book considers their security and presents the current research results that estimate the impact on blockchain-based systems if some of the cryptographic primitive break. Based on the example of Bitcoin, it shows that weak cryptographic primitives pose a possible danger for the ledger, which can be overcome through the use of the so-called post-quantum cryptographic approaches which are introduced as well.

URL:

Oxford University Press

Google Books

Further information:

Aktien als digitalisierte Werte

Hans Caspar von der Crone/Merens Derungs

SZW 2019, 481-497.

Abstract

Shares issued on a distributed ledger have already been designated as a future market standard. The potential of these dlt-shares is also acknowledged by the Swiss government, which has published a preliminary draft
on the adaptation of federal law to developments in distributed ledger technology earlier this year. This essay focuses on various mainly private law issues related to the issuance and transfer of such dlt-shares. In the first section we review whether current Swiss law is compatible with dlt-shares. In the second section we examine dlt-shares under the preliminary draft. The authors come to the conclusion that current Swiss law allows the issuance and transfer of dlt-shares. Contrary to other opinions, dlt-shares can be transferred by simple transfer of the respective token if a contract assignment agreement has been concluded («Vertragsübernahme»). The preliminary draft provides for the electronic registration of rights on dlt-based systems. As a new category of securities, these rights will also have securities functions. Positive aspects of the preliminary draft are the clear allocation of rights and responsibilities and the seamless integration of the new rights into the existing corporate and securities laws. However, technological restrictions will continue to play a role in the transfer of dlt-shares. In order to overcome these obstacles, a solution is proposed which links the distributed ledger to the system of intermediated securities.

Ethereum Gas Price Statistics

David Carl, Christian Ewerhart

University of Zurich, Department of Economics, Working Paper No. 373, 2020

Abstract

For users of the Ethereum network, the gas price is a crucial parameter that determines how swiftly the decentralized consensus protocol confirms a transaction. This paper studies the statistics of the Ethereum gas price. We start with some conceptual discussion of the gas price notion in view of the actual transaction-selection strategies used by Ethereum miners. Subsequently, we provide the descriptive statistics of what we call the threshold gas price. Finally, we identify and estimate a seasonal ARIMA (SARIMA) model for predicting the hourly median of the threshold gas price.

Finite blockchain games

Christian Ewerhart

Economics Letters 197 (2020)

Abstract

This paper studies the dynamic construction of a blockchain by competitive miners. In contrast to the literature, we assume a finite time horizon. Moreover, miners are rewarded for blocks that eventually become part of the longest chain. It is shown that popular mining strategies such as adherence to conservative mining or to the longest-chain rule constitute pure-strategy Nash equilibria. However, these equilibria are not subgame perfect.

Lightning Network: a second path towards centralisation of the Bitcoin economy

Jian-Hong Lin, Kevin Primicerio, Tiziano Squartini, Christian Decker, Claudio J.Tessone

arXiv:2002.02819

Abstract

The Bitcoin Lightning Network (BLN), a so-called “second layer” payment protocol, was launched in 2018 to scale up the number of transactions between Bitcoin owners. In this paper, we analyse the structure of the BLN over a period of 18 months, ranging from 14th January 2018 to 13th July 2019, at the end of which the network has reached 8.216 users, 122.517 active channels and 2.732,5 transacted bitcoins. Here, we consider three representations of the BLN: the daily snapshot one, the weekly snapshot one and the daily-block snapshot one. By studying the topological properties of the binary and weighted versions of the three representations above, we find that the total volume of transacted bitcoins approximately grows as the square of the network size; however, despite the huge activity characterising the BLN, the bitcoins distribution is very unequal: the average Gini coefficient of the node strengths is approximately 0.88 causing 10% (50%) the of the nodes to hold the 80% (99%) of the bitcoins at stake in the BLN (on average, across the entire period). Like for other economic systems, we hypothesise that local properties of nodes, like the degree, ultimately determine part of its characteristics. Therefore, we have tested the goodness of the Undirected Binary Configuration Model (UBCM) in reproducing the structural features of the BLN: the UBCM recovers the disassortative and the hierarchical character of the BLN but underestimates the centrality of nodes; this suggests that the BLN is becoming an increasingly centralised network, more and more compatible with a core-periphery structure. Further inspection of the resilience of the BLN shows that removing hubs leads to the collapse of the network into many components, an evidence suggesting that this network may be a target for the so-called split attacks.

Bitcoin Transaction Networks: an overview of recent results

Nicolò Vallarano, Claudio Tessone, Tiziano Squartini

arXiv:2005.00114

Abstract

Cryptocurrencies are distributed systems that allow exchanges of native (and non-) tokens among participants. The complete historical bookkeeping and its wide availability opens up an unprecedented possibility, i.e., that of understanding the evolution of their network structure while gaining useful insight on the relationships between user behaviour and cryptocurrency pricing in exchange markets. In this contribution we review some of the most recent results concerning the structural properties of Bitcoin Transaction Networks, a generic name referring to a set of different constructs: the Bitcoin Address Network, the Bitcoin User Network and the Bitcoin Lightning Network. A common picture that emerges out of analysing them all is that of a system growing over time, which becomes increasingly sparse, and whose structural organization at the mesoscopic level is characterised by the presence of a statistically-significant core-periphery structure. Such a peculiar topology is matched by a highly unequal distribution of bitcoins, a result suggesting that Bitcoin is becoming an increasingly centralised system at different levels.

Mining blocks in a row: A statistical study of fairness in Bitcoin mining

Sheng-Nan Li, Zhao Yang, Claudio J. Tessone

2nd IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2020), Toronto, Canada, May 2020

Abstract

The Bitcoin system keeps its ledger consistent in a blockchain by solving cryptographic problems, in a method called “Proof-of-Work”. The conventional wisdom asserts that the mining protocol is incentive-compatible. However, Eyal and Sirer in 2014 have discovered a mining attack strategy called selfish mining (SM), in which a miner (or a mining pool) publishes the blocks it mines selectively instead of immediately. SM strategy would have the impact of wasting resources of honest miners. Scholars proposed various extensions of the SM strategy and approaches to defense the SM attack. Whether selfish mining occurs in practice or not, has been subject of extensive debate. For the first time, in this paper we propose a method to identify selfish miners by detecting anomalies in the properties of consecutive blocks’ statistics. Furthermore, we extend our method to detect the mining cartels, in which miners secretly get together and share timely information. Our results provide evidence that these strategic behaviors take place in practice

URL:

Further information:

SC-FLARE: Cooperative DDoS Signaling based on Smart Contracts

Bruno Rodrigues, Spasen Trendafilov, Eder John Scheid, Burkhard Stiller

2nd IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2020), Toronto, Canada, May 2020, pp 1–3

Abstract

Distributed Denial-of-Service (DDoS) attacks remains as one of the major causes of concerns for service providers around the world. This paper introduces SC-FLARE, a Smart Contract (SC) based cooperative signaling protocol built on top of a Ethereum Proof-of-Authority Blockchain (BC) for the sharing of attack information, the exchange of incentives, and the tracking of reputation in a fully distributed and automated fashion. By making use of BC and SC, SC-FLARE provide the required collaborative platform without the burden to maintain, design, and develop special registries and gossip protocols for a cooperative defense.

A Controlled Natural Language to Support Intent-based Blockchain Selection

Eder John Scheid, Patrick Widmer, Bruno Rodrigues, Muriel Franco, Burkhard Stiller

2nd IEEE International Conference on Blockchain and Cryptocurrency (ICBC 2020), Toronto, Canada, May 2020, pp 1–9

Abstract

In the last years, cryptocurrencies have become increasingly popular along with their underlying distributed ledger technology, referred to as a Blockchain (BC). Nowadays, a wide variety of BC implementations are available. However, the selection of a suitable implementation for a particular application or use case is complex because it requires technical understanding of the underlying BC implementation aspects. Therefore, this paper proposes a Controlled Natural Language (CNL) to extends existing BC selection solutions to abstract underlying implementation details. The approach allows the specification abstract high-level policies, referred to as intents, in an English-based language. The approach is inspired by previous approaches from the network management field. Moreover, a state machine-based refinement technique is proposed to refine these intents into low-level BC selection policies. The results of the performance evaluation of the prototype implementation show that the refinement process presents a minimal overhead. In addition, the perceived intuitiveness of the CNL by users was assessed in a survey. The results of the survey suggest that technical and non-technical individuals benefit from an intentbased approach equally.

Standardization of Blockchain-based I2oT Systems in the I4 Era

Sina Rafati Niya, Eryk Schiller, Ile Cepilov, Burkhard Stiller

IEEE/IFIP Network Operations and Management Symposium (NOMS 2020), Budapest, Hungary. 2020, pp. 1-9

Abstract

In Industry 4.0 (I4), the Industrial Internet of Things(I2oT) data streams are prone to significant data manipulationrisks. The integration of Blockchains (BC) with I2oT may becomea solution preventing from this problem. This paper provides ablockchain agnostic Blockchain I2oT (BI2oT) architecture calledBIIT that allows developing a broad range of BC applicationsfully integrating Internet of Things (IoT). The mechanismsintroduced in BIIT aim at solutions that provide data reliability,limit the computational overhead, and enhance energy efficiency.BIIT is evaluated through real-world experimentation.

PleBeuS: a Policy-based Blockchain Selection Framework

Eder John Scheid, Daniel Lakic, Bruno Rodrigues, Burkhard Stiller

IEEE/IFIP Network Operations and Management Symposium (NOMS 2020), Budapest, Hungary. 2020, pp. 1-9

Abstract

Due to the growing interest in the blockchain (BC), several applications are being developed, taking advantage of the benefits that such technology promises to deliver, such as removal of Trust Third Parties (TTP) to verify transactions and data immutability. However, these applications require certain aspects, such as high transaction throughput or data privacy, that early BC implementations (e.g., Bitcoin) did not provide. Thus, a myriad of novel BC implementations was developed, which introduced the issue of choosing the right implementation for a specific use-case. This paper presents a framework, called PleBeuS, to address this selection issue by allowing users to specify policies that rule the automatic selection of the BC that data will be stored. The selection process relies on a cost-aware approach and considers both public and private implementations and their technical characteristics. Moreover, PleBeuS communicates with a BC-agnostic interoperability API to enforce transactions. The evaluation of the PleBeuS prototype showed that it is possible to automatically select a BC-based on user policies, considering cost thresholds and technical details (e.g., BC throughput, deployment), and reduce manual interaction.

Design and Implementation of Cast-as-Intended Verifiability for a Blockchain-Based Voting System

Christian Killer, Bruno Rodrigues, Raphael Matile, Eder John Scheid, Burkhard Stiller

Proceedings of the 35th Annual ACM Symposium on Applied Computing, 2020, pp. 286-293.

ABSTRACT

Digitization of electoral processes depends on confident systems that produce verifiable evidence. The design and implementation of voting systems has been widely studied in prior research, bringing together expertise in many fields. Switzerland is organized in a federal, decentralized structure of independent governmental entities. Thus, its decentralized structure is a real-world example for implementing an electronic voting system, where trust is distributed among multiple authorities.
This work outlines the design and implementation of a blockchain-based electronic voting system providing cast-as-intended verifiability. The generation of non-interactive zero-knowledge proofs of knowledge enables every voter to verify the encrypted vote, while maintaining the secrecy of the ballot. The Public Bulletin Board (PBB) is a crucial component of every electronic voting system, serving as a publicly verifiable log of communication and ballots – here a blockchain is used as the PBB. Also, the required cryptographic operations are in linear relation to the number of voters, making the outlined system fit for large-scale elections.

Toward scalable blockchains with transaction aggregation

Sina Rafati Niya, Fabio Maddaloni, Thomas Bocek, Burkhard Stiller

Proceedings of the 35th Annual ACM Symposium on Applied Computing, 2020, pp. 308-315.

Abstract

Blockchains (BCs) are back-linked chain of records termed as blocks. To establish decentralized trusted systems, BCs employ consensus mechanisms. During the past ten years, there have been various proposals of BC design and implementations. However, most of the developed sate of the art BCs suffer from scalability issues. In order to enhance the scalability of the BCs, this paper proposes a transaction aggregation mechanism on a Proof-of-Stake (PoS)-based BC. Having developed the transaction aggregation and double linked blocks, efficient prevention and control of the BC’s size growth is observed in the evaluated scenarios.

Threat Management Dashboard for a Blockchain Collaborative Defense

Christian Killer, Bruno Rodrigues, Burkhard Stiller

2019 IEEE Globecom Workshops (GC Wkshps), Waikoloa, HI, USA, 2019, pp. 1-6

Abstract:

The increasing number of Distributed Denial-of-Service (DDoS) attacks leads to a growing research and development interest in DDoS defense systems. As a response to the increasingly distributed nature of DDoS attacks, many organizations have demonstrated willingness to exchange information concerning threats, incidents, and mitigation strategies. Blockchain is, in this regard, a viable threat sharing platform, where different organizations can interact in a verifiable manner. This paper tackles the security visualization and management issue in a blockchain-based collaborative defense platform, defining an interactive dashboard displaying on-going threat mitigation status and enabling security analysts to react on threats on an individual or group level. The dashboard was implemented and evaluated on real hardware emulating the exchange of threats between three isolated Autonomous Systems (AS).

Scalable Transport Mechanisms for Blockchain IoT Applications

Eryk Schiller, Sina Rafati Niya, Timo Surbeck, Burkhard Stiller

44th Conference on Local Computer Networks (LCN 2019), Osnabrück, Germany, October 2019, pp. 34–41

Abstract

This paper studies various methods that improve the performance of Blockchain systems integrated with the Internet of Things (BIoT) using the LoRaWAN access method. Duty Cycle Enforcement (DCE) and Listen Before Talk (LBT) mechanisms as the channel access methods, Automatic Repeat reQuest (ARQ) on the Transport Layer, and transaction aggregation on the Application Layer are evaluated. The main focus is put on the system performance studying the maximal number of transactions submitted, reliability of transport schemes, and the energy efficiency of the BIoT system. The combination of LBT-based MAC, the ARQ-enabled Transport Layer, and transaction aggregation at the Application Layer provides a good trade-off between submitted transaction count, packet loss, and energy efficiency. The proposed scheme complies to the data integrity demands of BIoT applications by specifying a reliable data transmission scheme from IoT devices to the BC.

TradeMap: A FINMA-compliant Anonymous Management of an End-2-end Trading Market Place

Sina Rafati Niya, Sebastian Allemann, Arik Gabay, Burkhard Stiller

15th International Conference on Network and Service Management (CNSM 2019), Halifax, Canada, October 2019, pp. 1–5

Abstract:

Data leaks and privacy scandals have been a growing concern of the last decade. While most traditional, i.e., centralized, online platforms require users to register with their personal data, they potentially expose the user’s identity and data to be used for unintended purposes. This work proposes TradeMap as an integrated architecture, designing and enabling an online end-to-end (e2e) trading market place, while supporting anonymous management features. TradeMap addresses the Swiss Financial Market Supervisory Authority (FINMA) regulations by designing a FINMA-complaint Know Your Customer (KYC) platform. Additionally, TradeMap is based on blockchains and employs Ethereum Smart Contracts (SC). Thus, trust and anonymity between the market place and the KYC system relies on zero knowledge proof-based SCs used for user identification processes. With this management approach proposed, the user authentication is only verified within the KYC platform, providing a legally valid and fully anonymous online trading platform.

BUNKER: a Blockchain-based trUsted VNF pacKagE Repository

Eder John Scheid, Manuel Keller, Muriel Franco, Burkhard Stiller

16th Conference on the Economics of Grids, Clouds, Systems, and Services (GECON 2019), Leeds, UK, September 2019, pp. 188-196

Abstract

Current projects applying blockchain technology to enhance the trust of NFV environments do not consider the VNF repository. However, the blockchain’s properties can enhance trust by allowing to verify a VNF package’s integrity without relying (a) on a Trusted Third Party (TTP) for remote attestation or (b) a secure database. This paper presents BUNKER, a Blockchain-based trUsted VNF packagE Repository, intended to be integrated with traditional database-based package verification environments, acting as a trusted repository containing VNF package information. Moreover, BUNKER allows users to acquire VNFs without the need of a TTP using an Ethereum Smart Contract (SC). The SC automatically transfers license fees to the vendor once a VNF is acquired, and sends the VNF package’s link to the buyer before verifying its integrity.

GENEVIZ: a Visual Tool for the Construction and Blockchain-based Validation of SFC Packages

Muriel Franco, Martin Bucher, Eder Scheid, Lisandro Granville, Burkhard Stiller

16th Conference on the Economics of Grids, Clouds, Systems, and Services (GECON 2019), Leeds, UK, September 2019, pp. 15–28

Abstract

Network Functions Virtualization (NFV) decouples the network package performed by network functions from dedicated hardware appliance by running Virtual Network Functions (VNF) on commercial off-the-shelf hardware. Network operators can create customized network services by chaining multiple VNFs, defining a so-called Service Function Chaining (SFC). Because NFV became technically mature recently, the building of such SFCs still needs in-depth knowledge about NFV technology and its descriptors. Furthermore, there is a lack of tools that help to simplify the creation of SFCs. This paper, introduces GENEVIZ, a tool that provides a user-friendly interface for the creation of new SFCs as well as for importing and adjusting acquired SFCs (e.g., from marketplaces of VNFs), in order to create new SFCs based on existing ones. Therefore, this work addresses as well data integrity and provides the functionality to store and validate SFCs through the use of blockchains. Three case studies are presented to provide evidence of the technical feasibility of the solution proposed.

Cooperative Signaling of DDoS Attacks in a Blockchain-based Network

Bruno Rodrigues, Burkhard Stiller

ACM SIGCOMM 2019 Conference Posters and Demos, Beijing, China, August 2019, pp. 39–41

ABSTRACT

Driven by the increasing number of stationary and portable devices, Distributed Denial-of-Service (DDoS) attacks pose a major threat to Internet availability. While advantages of cooperative defenses have been widely recognized over traditional on-premise defenses, there is not a widespread deployment of such cooperative defenses. This work demonstrates the Blockchain Signaling System (BloSS), a modular, network-agnostic and cooperative DDoS defense system consisting of independent instances working together to mitigate attacks targeted at any member of this alliance.

SATOS: Storage Agnostic Tokens over Opaque and Substructural Types

Markus Knecht, Burkhard Stiller

2019 Crypto Valley Conference on Blockchain Technology (CVCBT), Rotkreuz, Switzerland, 2019, pp. 12-20

Abstract:

Public blockchains in support of Smart Contracts (SC), like Ethereum enable everyone to represent scarce, valuable resources (like cryptocurrencies) as so-called tokens. Token issuing and management was the first blockchain use case. However, programming languages and runtime systems used in the current blockchains for their SCs lack a secure and straightforward way to implement and handle tokens. The unnecessary complexity in doing so can lead to erroneous implementation of tokens and applications built on top of these, including the loss or theft of tokens as it happened. The most known attack was “TheDAO” attack which led to the “loss” of tokens, valued at that time at approximately 60 M US Dollar. A better and secure token representation directly embedded into a SC runtime and SC programming language could prevent loss of tokens. Thus this paper presents an approach including parts of a programming language using it. The core of the model is to use opaque and substructural data types together with an onchain soundness checker to generically represent tokens securely as values similar to integers and booleans. Such opaque data types enforce that only a designated piece of code can create values of that type. The substructural data types allow arbitrary values to express scarcity by preventing the duplication and elimination of values. The on-chain soundness checker ensures that the deployed code does not violate guarantees given by the type system, which includes opaque and substructural data types.

Security Management and Visualization in a Blockchain-based Collaborative Defense

Christian Killer, Bruno Rodrigues, Burkhard Stiller

2019 IEEE International Conference on Blockchain and Cryptocurrency (ICBC), Seoul, Korea (South), 2019, pp. 108-111

Abstract:

A cooperative network defense is one approach to fend off large-scale Distributed Denial-of-Service (DDoS) attacks. In this regard, the Blockchain Signaling System (BloSS) is a multi-domain, blockchain-based, cooperative DDoS defense system, where each Autonomous System (AS) is taking part in the defense alliance. Each AS can exchange attack information about ongoing attacks via the Ethereum blockchain. However, the currently operational implementation of BloSS is not interactive or visualized, but the DDoS mitigation is automated. In realworld defense systems, a human cybersecurity analyst decides whether a DDoS threat should be mitigated or not. Thus, this work presents the design of a security management dashboard for BloSS, designed for interactive use by cyber security analysts.

A Blockchain-based Scientific Publishing Platform

Sina Rafati Niya, Lucas Pelloni, Severin Wullschleger, Andreas Schaufelbühl, Thomas Bocek, Burkhard Stiller, Lawrence Rajendran

2019 IEEE International Conference on Blockchain and Cryptocurrency (ICBC), Seoul, Korea (South), 2019, pp. 329-336

Abstract:

Out casting, sharing, and publishing the collected knowledge, experiences, and outputs of scientific works, regardless of being empirical or purely theoretical, has always been one of the key assets of human evolution. However, on one hand, re-usability of published work depends on accessibility, and, on the other hand, om the correctness of published work. Studies on the traditional scientific publishing platforms reveal many deficits with those systems, which had been addressed with the proposed blockchain-based solution called Eureka. Eureka enables high quality reviews of tthe published work, while incentivizing authors and reviewers to participate in this decentralized, open, and public scientific publishing platform.

A Platform-independent, Generic-purpose, and Blockchain-based Supply Chain Tracking

Sina Rafati Niya, Danijel Dordevic, Atif Ghulam Nabi, Tanbir Mann, Burkhard Stiller

2019 IEEE International Conference on Blockchain and Cryptocurrency (ICBC), Seoul, Korea (South), 2019, pp. 11-12

Abstract:

Supply Chain Tracking (SCT) is considered as a major challenge for stakeholders of heterogeneous production, processing, transporting, storing, and selling systems. Studies on solutions in SCT reveal that many centralized SCT applications lack a design, which can support or even enable main features of a reliable, transparent, and publicly accessible SCT system for end users. This work demonstrates the implementation of a SCT application which, employs SC on the Ethereum blockchain (BC). This Decentralized Application (Dapp) provides a hardware-and platform-independent approach that flexibly enables multiple object combinations and transformations to be tracked with a use case-agnostic design and utilization.

EUREKA – A Minimal Operational Prototype of a Blockchain-based Rating and Publishing System

Andreas Schaufelbühl, Sina Rafati Niya, Lucas Pelloni, Severin Wullschleger, Thomas Bocek, Burkhard Stiller, Lawrence Rajendran

2019 IEEE International Conference on Blockchain and Cryptocurrency (ICBC), Seoul, Korea (South), 2019, pp. 13-14

Abstract:

Today’s number of reputable academical publishers is dominated by few key players. This imbalance of supply and demand in publishing academic work makes the entire process inefficient. EUREKA is a blockchain-based scientific publishing platform, developed to address this imbalance. It offers the opportunity of a fair reward distribution for all contributors and immediate ownership rights to authors of an article. For the demonstration, the platform including the back-end and frontend integrated into the Ethereum blockchain is shown, and the interaction processes of users i.e., authors and reviewers are presented.

Adaptation of Proof-of-Stake-based Blockchains for IoT Data Streams

Sina Rafati Niya, Eryk Schiller, Ile Cepilov, Fabio Maddaloni, Timo Surbeck, Kürsat Aydinli, Thomas Bocek

2019 IEEE International Conference on Blockchain and Cryptocurrency (ICBC), Seoul, Korea (South), 2019, pp. 15-16

Abstract:

Proof-of-Work (PoW) in Blockchains (BC), which is a widely used consensus algorithm, suffers from high power consumption of miners and low transaction rates. This work demonstrates a Proof-of-Stake (PoS)-based BC called Bazo, which is specially designed and adapted for Internet of Things (IoT) data streams. Bazo displays enhanced performance in terms of energy consumption and transactions processing in comparison to PoW-based BC. To further improve performance of Bazo, sharding and transaction aggregation methods are employed. Moreover, IoT-BC adaptation helpers of a modular and layered architecture are provided to allow wireless devices to submit data into the BC. The designed architecture can support multiple hardware and software platforms as well as network technologies.

Cast-as-Intended Verifiability in Blockchain-based Electronic Voting

Raphael Matile, Bruno Rodrigues, Eder John Scheid, Burkhard Stiller

2019 IEEE International Conference on Blockchain and Cryptocurrency (ICBC), Seoul, Korea (South), 2019, pp. 24-28

Abstract:

Democracy in the digital age has attracted a lot of public attention in recent years. However, bringing the human right of secrecy in voting to electronic systems is difficult. Properties, such as the possibility of verifying universally that any vote counted was indeed carrying the decision made by a voter, are often conflicting and a trade-off must be found. This paper proposes a blockchain-based electronic voting system providing explicitly cast-as-intended verifiability. By using a non-interactive zero-knowledge proof of knowledge any voter can verify that his or her encrypted vote represents the decision voted for while maintaining at the same time the secrecy of the ballot. In addition, any required cryptographic material can be generated in linear time with respect to the number of voters, making the system suitable for large scale elections, thus scalable.

BRAIN: Blockchain-based Reverse Auction for Infrastructure Supply in Virtual Network Functions-as-a-Service

Muriel Franco, Eder Scheid, Lisandro Granville, Burkhard Stiller

2019 IFIP Networking Conference (IFIP Networking), Warsaw, Poland, 2019, pp. 1-9

Abstract:

Network Functions Virtualization (NFV) is transforming the way in which network operators acquire and manage network services. By using virtualization technologies to move packet processing from dedicated hardware to software, NFV has introduced a new market focused on the offer and distribution of Virtual Network Functions (VNF). Infrastructure Providers (InP) can benefit from an NFV market by providing their infrastructures to fulfill demands of end-users that, in turn, acquire VNFs-as-a-Service (VNFaaS). In this context, solutions that promote the competition between InPs can lead to lower prices, while increasing VNF performance to accommodate specific demands of end-users. In this paper, BRAIN, a blockchain-based reverse auction is presented to introduce an auditable solution in which InPs can compete to host VNFs taking into account the demands of each particular end-user. Such a solution helps reduce costs involved in VNF’s commercialization and also monetize NFV-enabled infrastructures. BRAIN is supported by a case study that provides evidence of the solution’s feasibility and effectiveness. A discussion regarding blockchain advantages and drawbacks in this use-case (e.g., additional costs and time) concludes this paper.

Enabling Dynamic SLA Compensation Using Blockchain-based Smart Contracts

Eder Scheid, Bruno Rodrigues, Lisandro Granville, Burkhard Stiller

2019 IFIP/IEEE Symposium on Integrated Network and Service Management (IM), Arlington, VA, USA, 2019, pp. 53-61.

Abstract:

Service Level Agreements (SLA) are documents that specify what Service Providers (SP) are delivering to customers. They contain information about the service, such as target performance level or monthly availability, and penalties for the violations of the SLA. The information about the penalties is essential because if the SP does not deliver what is defined, the customer must be compensated accordingly. However, the current compensation process is cumbersome and complex because of the amount of involved manual effort. To address this issue, it is proposed in this paper an approach based on blockchain and Smart Contracts (SC) to automate the compensation process while enabling dynamic payments during the SLA lifetime. The proposed approach was evaluated in an use case that simulates the management of a Quality of Service SLA between an SP and a customer. Based on the performed evaluation, parts of the SLA management process were successfully automated using a decentralized solution, and the payment of the compensation occurred without the intervention of a third party.

Toward a Policy-based Blockchain Agnostic Framework

Eder Scheid, Bruno Rodrigues, Burkhard Stiller

2019 IFIP/IEEE Symposium on Integrated Network and Service Management (IM), Arlington, VA, USA, 2019, pp. 609-613.

Abstract:

Blockchain technology is developing at a rapid pace. For consumers that are only interested in simplifying processes and reducing costs by using a blockchain solution a new problem has occurred. It is not only necessary to select the appropriate solution, but also to configure and operate considering blockchain interoperability with different chains. For the industry, there is a need for solutions based on open standards. This paper proposes a Policy-based Blockchain Agnostic Framework that not only connects different blockchains but also facilitates their configuration and operation. Moreover, a case study is presented considering the cold-chain supply-chain, where each actor defines its policies based on blockchain requirements.

A Reputation and Reward Scheme for a Cooperative Network Defense

Andreas Gruhler, Bruno Rodrigues, Burkhard Stiller

2019 IFIP/IEEE Symposium on Integrated Network and Service Management (IM), Arlington, VA, USA, 2019, pp. 71-79.

Abstract

Distributed Denial-of-Service (DDoS) attacks rise in frequency, diversity, and intensity. Often, centralized defense approaches lack hard- and software capabilities. A cooperative, multi-domain DDoS mitigation system provides defense services on top of an existing, distributed infrastructure. However, participants in these systems lack incentives for cooperation and reputation. Thus, reward systems can fill this gap by providing necessary incentives for cooperation among service providers and consumers. This paper presents the design, implementation, and evaluation of a reputation scheme for the Blockchain Signaling System (BloSS). A smart contract-enabled process automates reputation management to diminish malicious behavior by incentive design. Among other metrics, Beta reputation provides intelligence to identify and reward honest participants.

Evaluating a Blockchain-based Cooperative Defense

Bruno Rodrigues; Lukas Eisenring ; Eder Scheid ; Thomas Bocek ; Burkhard Stiller

2019 IFIP/IEEE Symposium on Integrated Network and Service Management (IM), Arlington, VA, USA, 2019, pp. 533-538.

Abstract

The volume of traffic generated by modern Distributed Denial-of-Service (DDoS) attacks suggests that centralized defenses are not the most effective approach to counter these attacks. An alternative to reduce the burden of detection and mitigation is to combine centralized defense systems, creating a global and cooperative protection system. However, existing approaches suffer from the complexity of deployment and operation across different systems. Blockchains appear in this scenario as an alternative to simplify the exchange of information in a cooperative defense. This work evaluates in both local and global experimentations the performance of the blockchain system proposed in concerning the latency to perform the signaling of blacklisted addresses.

A Taxonomy of Blockchain Technologies: Principles of Identification and Classification

Paolo Tasca, Claudio J. Tessone

Ledger, 4 (2019)

Abstract

A comparative study across the most widely known blockchain technologies is conducted with a bottom-up approach. Blockchains are disentangled into building blocks. Each building block is then hierarchically classified in main and subcomponents. Then, alternative layouts for the subcomponents are identified and compared between them. Finally, a taxonomy tree summarises the study and provides a navigation tool across different blockchain architectural configurations.

Bifröst: a Modular Blockchain Interoperability API

Eder John Scheid, Timo Hegnauer, Bruno Rodrigues, Burkhard Stiller

2019 IEEE 44th Conference on Local Computer Networks (LCN), Osnabrueck, Germany, 2019, pp. 332-339

Abstract:

The blockchain (BC) world is rapidly becoming a universe of several ledgers designed for a specific purpose, holding data previously stored (i.e., siloed) in centralized databases. The use of different BCs for the same purpose could hamper the frictionless exchange of data or value. On one hand, it is natural that there are competing implementations exploring the benefits of BC. On the other hand, the problem of siloed data re-emerges, with respect to isolated chains. In this regard, BC interoperability is necessary to connect different BCs, exchanging information and assets. Moreover, to foster BC employment, developers must be able to interact with such different BCs without knowing the details of each implementation. This paper presents a novel solution, called Bifröst, to store and retrieve data on different BCs. Bifröst employs a notary scheme, which allows for connectivity to different BCs. The presented prototype is highly modular and currently implements seven adapters to popular BC implementations, including Bitcoin, Ethereum, and Stellar. The developed prototype was evaluated concerning performance, security, and data size to verify the feasibility of such an implementation and assess design decisions taken during its development.

The Bitcoin game: Ethno-resonance as method

Donncha Kavanagh, Gianluca Miscione, PJ Ennis

Organization 26.4 (2019): 517-536

Abstract

The global financial crisis and the contemporaneous emergence of the digital currency Bitcoin invite us to think about money and how it often functions almost imperceptibly in society. In this article, we show that Bitcoin is a ‘new object of concern’ that also compels us to reimagine ethnography in a digital age. We present a method, which we term ethno-resonance, that is both a reaction to the conditions presented by the Bitcoin phenomenon and a way of maintaining critical distance from its cyberlibertarian politics. We explicate six aspects of the method, framed around answers to what, why, how, who, when and where questions. Applied to cryptocurrencies, the method leads us to depict Bitcoin as a game, and we analyse the game’s dynamics through mapping the interplay between four foundational myths that animate, complicate and sustain the game. More broadly, this contributes to our understanding of the nature of money and alternative currencies.

Examining Gentle Rivalry: Decision-Making in Blockchain Systems

Rafael Ziolkowski, Geetha Parangi, Gianluca Miscione and Gerhard Schwabe

52nd Hawaii International Conference on System Sciences (HICSS 2019), Maui, Hawaii, 8-13 January 2019.

Abstract

The blockchain comes with the promise of being a disruptive technology with the potential for novel ways of interaction in a wide range of applications. Although scholarly interest in the technology is growing, a broad analysis of blockchain applications from a governance perspective lacks to date. This research pays special attention to the governance of blockchain systems and illustrates core governance decisions on 15 blockchain systems from four application domains. Based on academic literature, semi-structured interviews with representatives from those companies, and content analysis of grey literature, different blockchain governance decisions have been derived and their enactment described. The identification of them enriches the scarce body of knowledge on blockchain systems with a better understanding of how key governance decisions are enacted in practice.

Exploring Blockchain Value Creation: The Case of the Car Ecosystem

Ingrid Bauer, Liudmila Zavolokina, Fabian Leisibach and Gerhard Schwabe

52nd Hawaii International Conference on System Sciences (HICSS 2019), Maui, Hawaii, 8-12 January 2019.

Abstract

Blockchain is expected to create a variety of new opportunities for businesses. Yet, little is known about how companies can exploit business value from the technology. However, without a clear understanding of how, and corresponding adaption of business practices, the realization of value is doomed to failure. Hence, we contribute to this gap by analyzing and explicating the specificities of value creation from blockchain in the ecosystem of a car. In the course of an exploratory case analysis we conducted interviews and workshops with industry and blockchain experts from five diverse stakeholder groups. In brief, we provide early evidence that (1) blockchain enables value creation through: Distributed Product Innovation, Controlled Customer Intimacy and Shared Operational Efficiency. Further, (2) we derive guidelines and discuss learnings for other businesses aiming to leverage value from blockchain technology.

Buyers of lemons: addressing buyers’ needs in the market for lemons with blockchain technology

Liudmila Zavolokina, Gianluca Miscione and Gerhard Schwabe

52nd Hawaii International Conference on System Sciences (HICSS 2019), Maui, Hawaii, 8-12 January 2019.

Abstract

The automotive market is in the top three markets with the least trust from consumers. In particular, in the second-hand car market, consumers suffer from such problems as the car being in worse condition than initially indicated, accident damage that is not disclosed, fraud, etc. Akerlof, described the market for used cars as an example of the problem of information asymmetries and resulting quality uncertainty. In order to cope with quality uncertainties, used car buyers actively engage themselves in information seeking. Blockchain technology promises to automatize the tracking of cars through their lifecycles and provide reliable information at any point in time it is needed. In our study, we investigate the problems car buyers face during information seeking and propose requirements for the design of a blockchain-based system to address these.

To Token or not to Token: Tools for Understanding Blockchain Tokens

Luis Oliveira, Liudmila Zavolokina, Ingrid Bauer and Gerhard Schwabe

International Conference of Information Systems (ICIS 2018), San Francisco, USA, 12-16 December 2018.

Abstract

The growing usage of tokens in real-world blockchain projects – mostly visible in ICOs – has unveiled the need to understand what blockchain tokens in fact represent and how they relate to their underlying business model. Previous research has contributed to this gap but often lacks a comprehensive understanding of tokens and their design as well as of the growing and rapidly-changing complexity in token landscape. This has crucial implications for assessing tokens’ value and utility. Applying a structured, scientific approach towards blockchain tokens, we provide a comprehensive token classification and a decision-aid on token design. This is based on a literature review and an empirical study to cover this research gap. Our work offers a novel contribution in an emerging field within the Blockchain research domain and proposes structured analytical tools which can be used by both practitioners and researchers.

Incentivizing Data Quality in Blockchains for Inter-Organizational Networks – Learning from the Digital Car Dossier

Liudmila Zavolokina, Florian Spychiger, Claudio J. Tessone and Gerhard Schwabe

International Conference of Information Systems (ICIS 2018), San Francisco, USA, 12-16 December 2018.

Abstract

Recent research reports the need for consistent incentives in blockchain-based systems. In this study, we investigate how incentives for a blockchain-based inter-organizational network should be designed to ensure a high quality of data, exchanged and stored within the network. For this, we use two complementary methodological approaches: an Action Design Research approach in combination with agent-based modelling, and demonstrate, through the example of a real-world blockchain project, how such an incentive system may be modelled. The proposed incentive system features a rating mechanism influenced by measures of data correction. We evaluate the incentive system in a simulation to show how effective the system is in terms of sustaining a high quality of data. Thus, the paper contributes to our understanding of incentives in inter- organizational settings and, more broadly, to our understanding of incentive mechanisms in blockchain economy.

Consensus through Blockchains: Exploring Governance across interorganizational Settings

Rafael Ziolkowski, Gianluca Miscione and Gerhard Schwabe

International Conference of Information Systems (ICIS 2018), San Francisco, USA, 12-16 December 2018.

Abstract

The blockchain technology challenges the view on established modes of governance by offering distributed authentication without the need for a central authority, which is well-exemplified by Bitcoin. While the governance of and through Bitcoin is well- accentuated in research, we spotlight impacts on governance which blockchain-based systems bring to inter-organizational settings as well as their purpose. To build our arguments, we explore those impacts on two contrasting cases from the domains of automotive and public administration and relate them to cryptocurrencies. Relying on interviews with experts from said organizations utilizing blockchain technology, and a content analysis of related grey literature, we discuss established forms of governance as well as platforms and infrastructures against the impacts which blockchain-based systems cause. After referring those to the concepts of markets, hierarchies, networks, and tribes, we critically reflect on their purpose by utilizing the notions of infrastructures and platforms, and conclude blockchain-based systems to possibly alter the way established modes of governance are enacted.

Network-based indicators of Bitcoin bubbles

Alexandre Bovet, Carlo Campajola, Jorge F. Lazo, Francesco Mottes, Iacopo Pozzana, Valerio Restocchi, Pietro Saggese, Nicoló Vallarano, Tiziano Squartini, Claudio J. Tessone

arXiv:1805.04460

Abstract

The functioning of the cryptocurrency Bitcoin relies on the open availability of the entire history of its transactions. This makes it a particularly interesting socio-economic system to analyse from the point of view of network science. Here we analyse the evolution of the network of Bitcoin transactions between users. We achieve this by using the complete transaction history from December 5th 2011 to December 23rd 2013. This period includes three bubbles experienced by the Bitcoin price. In particular, we focus on the global and local structural properties of the user network and their variation in relation to the different period of price surge and decline. By analysing the temporal variation of the heterogeneity of the connectivity patterns we gain insights on the different mechanisms that take place during bubbles, and find that hubs (i.e., the most connected nodes) had a fundamental role in triggering the burst of the second bubble. Finally, we examine the local topological structures of interactions between users, we discover that the relative frequency of triadic interactions experiences a strong change before, during and after a bubble, and suggest that the importance of the hubs grows during the bubble. These results provide further evidence that the behaviour of the hubs during bubbles significantly increases the systemic risk of the Bitcoin network, and discuss the implications on public policy interventions.

Tribal Governance: The Business of Blockchain Authentication

Gianluca Miscione, Rafael Ziolkowski, Liudmila Zavolokina, Gerhard Schwabe

Hawaii International Conference on System Sciences (HICSS), 2018

Abstract

The blockchain technology offers a novel mode of distributed authentication, which does not depend on a central authority. We consider this novelty against established governance modes. We illustrate our argument by paying special attention to blockchain-based authentication functions in the empirical domain of land registries across the world. Based on interviews with representatives from organizations deploying blockchain, and content analysis of related grey literature, we discuss established governance ideal types against what the rivalry that cryptocurrencies and blockchains bring to digital settings. After referring to market, hierarchy, network, and bazaar, we conclude outlining the prospects of a different, blockchain-related governance mode called ‘tribal’ that better captures the ‘togetherness’ which rivalry originates.

Blockchain Technologies from the Consumers’ Perspective: What Is There and Why Should Who Care?

Manuel Schlegel, Liudmila Zavolokina and Gerhard Schwabe

51st Hawaii International Conference on System Sciences (HICSS 2018), Hawaii, 4-6 January 2018.

Abstract

The blockchain, the ledger that underlies the famous cryptocurrency Bitcoin, has huge implications for many industries. There have been various papers dedicated to research how blockchain technology will transform businesses and industries. However, current research lacks an overview of what the blockchain implies for the biggest stakeholder of these businesses and industries: consumers. This paper aims to provide an overview of how the blockchain affects consumers. We conduct a systematic literature review and enrich it with interview-based knowledge from blockchain experts to show how blockchain technology changes business sectors, name affected consumers in these sectors, derive implications for these consumers and list existing as well as currently emerging blockchain-based products and services. Finally, we warn of the technical, institutional and human challenges and manifold pitfalls blockchain technology must overcome to gain widespread adaptation among consumers.

The digital traces of bubbles: feedback cycles between socio-economic signals in the Bitcoin economy

David Garcia, Claudio J. Tessone, Pavlin Mavrodiev and Nicolas Perony

Journal of the Royal Society: Interface, pp. 20140623, vol. 11 (2014) 

Abstract

What is the role of social interactions in the creation of price bubbles? Answering this question requires obtaining collective behavioural traces generated by the activity of a large number of actors. Digital currencies offer a unique possibility to measure socio-economic signals from such digital traces. Here, we focus on Bitcoin, the most popular cryptocurrency. Bitcoin has experienced periods of rapid increase in exchange rates (price) followed by sharp decline; we hypothesize that these fluctuations are largely driven by the interplay between different social phenomena. We thus quantify four socio-economic signals about Bitcoin from large datasets: price on online exchanges, volume of word-of-mouth communication in online social media, volume of information search and user base growth. By using vector autoregression, we identify two positive feedback loops that lead to price bubbles in the absence of exogenous stimuli: one driven by word of mouth, and the other by new Bitcoin adopters. We also observe that spikes in information search, presumably linked to external events, precede drastic price declines. Understanding the interplay between the socio-economic signals we measured can lead to applications beyond cryptocurrencies to other phenomena that leave digital footprints, such as online social network usage.