Bitcoin Transaction Malleability and MtGox

In Bitcoin, transaction malleability describes the fact that the signatures that prove the ownership of bitcoins being transferred in a transaction do not provide any integrity guarantee for the signatures themselves. This allows an attacker to mount a malleability attack in which it intercepts, modifies, and rebroadcasts a transaction, causing the transaction issuer to believe that the original transaction was not confirmed. In February 2014 MtGox, once the largest Bitcoin exchange, closed and filed for bankruptcy claiming that attackers used malleability attacks to drain its accounts. In this work we use traces of the Bitcoin network for over a year preceding the filing to show that, while the problem is real, there was no widespread use of malleability attacks before the closure of MtGox

Blockchain: A Graph Primer

Bitcoin and its underlying technology Blockchain have become popular in recent years. Designed to facilitate a secure distributed platform without central authorities, Blockchain is heralded as a paradigm that will be as powerful as Big Data, Cloud Computing and Machine learning. Blockchain incorporates novel ideas from various fields such as public key encryption and distributed systems. As such, a reader often comes across resources that explain the Blockchain technology from a certain perspective only, leaving the reader with more questions than before. We will offer a holistic view on Blockchain. Starting with a brief history, we will give the building blocks of Blockchain, and explain their interactions. As graph mining has become a major part its analysis, we will elaborate on graph theoretical aspects of the Blockchain technology. We also devote a section to the future of Blockchain and explain how extensions like Smart Contracts and De-centralized Autonomous Organizations will function. Without assuming any reader expertise, our aim is to provide a concise but complete description of the Blockchain technology.Comment: 16 pages, 8 figure

Security Threats Classification in Blockchains

Blockchain, the foundation of Bitcoin, has become one of the most popular technologies to create and manage digital transactions recently. It serves as an immutable ledger which allows transactions take place in a decentralized manner. This expeditiously evolving technology has the potential to lead to a shift in thinking about digital transactions in multiple sectors including, Internet of Things, healthcare, energy, supply chain, manufacturing, cybersecurity and principally financial services. However, this emerging technology is still in its infancy. Despite the huge opportunities blockchain offers, it suffers from challenges and limitation such as scalability, security, and privacy, compliance, and governance issues that have not yet been thoroughly explored and addressed. Although there are some studies on the security and privacy issues of the blockchain, they lack a systematic examination of the security of blockchain systems. This research conducted a systematic survey of the security threats to the blockchain systems and reviewed the existing vulnerabilities in the Blockchain. These vulnerabilities lead to the execution of the various security threats to the normal functionality of the Blockchain platforms. Moreover, the study provides a case-study for each attack by examining the popular blockchain systems and also reviews possible countermeasures which could be used in the development of various blockchain systems. Furthermore, this study developed taxonomies that classified the security threats and attacks based on the blockchain abstract layers, blockchain primary processes and primary business users. This would assist the developers and businesses to be attentive to the existing threats in different areas of the blockchain-based platforms and plan accordingly to mitigate risk. Finally, summarized the critical open challenges, and suggest future research directions

A cybersecurity control framework for blockchain ecosystems

This paper proposes a cybersecurity control framework for blockchain ecosystems, drawing from risks identified in the practitioner and academic literature. The framework identifies thirteen risks for blockchain implementations, ten common to other information systems and three risks specific to blockchains: centralization of computing power, transaction malleability, and flawed or malicious smart contracts. It also proposes controls to mitigate the risks identified; some were identified in the literature and some are new. Controls that apply to all types of information systems are adapted to the different components of the blockchain ecosystem

CRYPTOCURRENCY: A MINE OF CONTROVERSIES

Cryptocurrency is attracting the attention of many disciplines. Based on a systematic literature review, thestate of art of academic research on cryptocurrency was investigated, demonstrating its complexity andthe lack of consensus about several issues, as its definition, its operation without a financial institution,the impacts on economy and its future developments. Considering these issues, Actor-Network Theorywas selected as a theory that can provide methods, such as controversy mapping, to understand thiscomplex subject. The article analyzes this scenario, presenting a set of research topics that can beconsidered to study controversies related to cryptocurrency.Cryptocurrency is attracting the attention of many disciplines. Based on a systematic literature review, thestate of art of academic research on cryptocurrency was investigated, demonstrating its complexity andthe lack of consensus about several issues, as its definition, its operation without a financial institution,the impacts on economy and its future developments. Considering these issues, Actor-Network Theorywas selected as a theory that can provide methods, such as controversy mapping, to understand thiscomplex subject. The article analyzes this scenario, presenting a set of research topics that can beconsidered to study controversies related to cryptocurrency

Impact of Blockchain on Financial Technology Innovation in the Banking, Financial Services and Insurance (BFSI) Sector

This research paper aims to highlight the progression of the technological advancements emerging in the BFSI sector across the globe, evaluate them, and find the merits and shortcomings in this sector using literature review assisted by the prior knowledge from the renowned works published in reputed journals. The information was obtained from secondary sources, thereby helping us draw a picture of the existing state of technology in the BFSI sector and its future potential/applicability within the field. We have used advanced search criteria of two levels to comprehensively cover the existing research papers on the topic for evaluation. With the rising need for digital change, banks look up to speed up the existing plans to arrange authoritative changes driven by the new initiatives. Artificial intelligence companies in the upcoming years will thrive. Banks will make all the efforts to utilize their advances to lessen the cost, mechanize all ordinary procedures, and separate administration levels through personal information which was not accessible before

Blockchain Technology and Trust Relationships in Trade Finance

Blockchain technology has been advocated as a possible solution to enduring trust issues among trading partners in trade finance. We conducted in-depth interviews with industry experts to examine how blockchain technology influences the trust relationships among trading partners. Our results show that the technology enhances trust relationships by (1) improving the security of transactions and data exchanges, (2) facilitating the expression of benevolence, (3) enhancing the efficiency and the quality of communication, and (4) increasing the predictability of trading partners. The paper concludes with implications for both research and practice

Anonymous, Attribute Based, Decentralized, Secure, and Fair e-Donation

E-cash and cryptocurrency schemes have been a focus of applied cryptography for a long time. However, we acknowledge the continuing need for a cryptographic protocol that provides global scale, decentralized, secure, and fair delivery of donations. Such a protocol would replace central trusted entities (e.g., charity organizations) and guarantee the privacy of the involved parties (i.e., donors and recipients of the donations). In this work, we target this online donation problem and propose a practical solution for it. First, we propose a novel decentralized e-donation framework, along with its operational components and security definitions. Our framework relies on a public ledger that can be realized via a distributed blockchain. Second, we instantiate our e-donation framework with a practical scheme employing privacy-preserving cryptocurrencies and attribute-based signatures. Third, we provide implementation results showing that our operations have feasible computation and communication costs. Finally, we prove the security of our e-donation scheme via formal reductions to the security of the underlying primitives

Blockchain na evropské úrovni

Blockchain na evropské úrovni Abstrakt Cílem této diplomové práce je poskytnout základní přehled technologie blockchain, jejích vlastností a potenciálního využití, včetně přehledu evropských předpisů, které se této technologie mohou za určitých podmínek dotýkát. V první kapitole diplomová práce poskytuje právní rámec primárního práva EU, který zakládá nebo může založit pravomoc EU zabývat se technologií blockchain, v závislosti na její právní kvalifikaci (zejména v souvislosti s vnitřním trhem - zejména volný pohyb služeb či kapitálu). V druhé a třetí kapitole je uveden základní popis funkcionalit blockchainu a kryptoměn a souvisejících služeb. Detailní popis je poskytnut v přílohách I-IV této diplomové práce. Zároveň je posouzen právní status a regulace kryptoměn, které tvoří základ technologií založených na blockchainu, a to jak na evropské úrovni, tak na úrovni členských států a dalších světových jurisdikcí. Součástí posouzení je i nedávný rozsudek SDEU Hedqvist, dle kterého se na dvousměrné směnárenské služby (nákup kryptoměn za fiat měny a naopak) uplatní výjimka z povinnosti odvést DPH v souladu s VAT směrnicí. Vzhledem k odůvodnění SDEU i generálního advokáta může tento rozsudek v budoucnu významně ovlivnit vývoj interpretace právního statusu kryptoměn a blockchainu obecně. Kromě kryptoměn je rovněž...Blockchain at the European Level Abstract The objective of this master thesis is to provide a basic overview of the blockchain technology, its features and its potential utilization, including an overview of European legal regulations that might be applicable to the technology, under certain conditions. In the first chapter, the master's thesis sets forth the legal framework of the EU primary law that establishes or can establish the EU's competence to act in the matters of blockchain technology, depending on its legal qualification (especially in the context of the internal market - namely the free movement of services and capital). The second and third chapters provide essential description of features of blockchain and cryptocurrency and related services. A more detailed description is provided in Annexes I-IV of this thesis. Further, the legal status and applicable regulation of cryptocurrencies are assessed at the European and national levels and in terms of other global jurisdictions. The assessment also includes the recent CJEU's judgment in the case Hedqvist, according to which bidirectional exchange services (purchase of cryptocurrency for fiat currency and vice versa) are to be exempted from VAT obligation under the VAT directive. In line with the CJEU's reasoning and the Advocate General's...Katedra evropského právaDepartment of European LawFaculty of LawPrávnická fakult