Aug 1, 2018·2018 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/ 12th IEEE International Conference On Big Data Science And Engineering (TrustCom/BigDataSE)
In this paper, we focus on the efficiency improvement of the content distribution network while endow this framework with controllability, where CHs(Content Helpers) have restricted distribution scope and thus the economic benefits of CP(Content Provider) are protected. We propose a novel controllable content distribution framework by using the blockchain technology as well as the iterative self organizing data analysis techniques algorithm (ISODATA), which is an improved k-means clustering method. To implement an incentive and consensus mechanism utilizing proof-of-stake, we employ smart contract to enforce content distribution in an autonomous way. We conduct some experiments to verify the validity and feasibility of the proposed framework. The experimental results demonstrated show that our framework has the advantages of high efficiency, low latency, and good scalability.
Bitcoin is a decentralized crypto-currency, which is based on the peer-to-peer network, and was introduced by Satoshi Nakamoto in 2008. Bitcoin transactions are written by using a scripting language. The hash value of a transaction’s script is used to identify the transaction over the network. In February 2014, a Bitcoin exchange company, Mt. Gox, claimed that they had lost hundreds of millions US dollars worth of Bitcoins in an attack known as transaction malleability. Although known about since 2011, this was the first known attack that resulted in a company loosing multi-millions of US dollars in Bitcoins. Our reason for writing this paper is to understand Bitcoin transaction malleability and to propose an efficient solution. Our solution is a softfork (i.e., it can be gradually implemented). Towards the end of the paper we present a detailed analysis of our scheme with respect to various transaction malleability-based attack scenarios to show that our simple solution can prevent future incidents involving transaction malleability from occurring. We compare our scheme with existing approaches and present an analysis regarding the computational cost and storage requirements of our proposed solution, which shows the feasibility of our proposed scheme.
Sujaya Maiyya, Victor Zakhary, Divyakant Agrawal, Amr El Abbadi
Bitcoin is a successful and interesting example of a global scale peer-to-peer cryptocurrency that integrates many techniques and protocols from cryptography, distributed systems, and databases. The main underlying data structure is blockchain, a scalable fully replicated structure that is shared among all participants and guarantees a consistent view of all user transactions by all participants in the cryptocurrency system. In this tutorial, we discuss the basic protocols used in blockchain, and elaborate on its main advantages and limitations. To overcome these limitations, we provide the necessary distributed systems background in managing large scale fully replicated ledgers, using Byzantine Agreement protocols to solve the consensus problem. Finally, we expound on some of the most recent proposals to design scalable and efficient blockchains. The focus of the tutorial is on the distributed systems and database technical aspects of the recent innovations in blockchains.
Aug 1, 2018·2018 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications/ 12th IEEE International Conference On Big Data Science And Engineering (TrustCom/BigDataSE)
Saqib Ali, Guojun Wang, Bebo White, Roger Leslie Cottrell
The blockchain is an innovative technology which opened doors to new applications for solving numerous problems in distributed environments. In this work, we design a blockchain-based data storage and access framework for PingER (worldwide end-to-end Internet performance measurement project) to remove its total dependence on a centralized repository. We use the permissioned blockchain and Distributed Hash Tables (DHT) for this purpose. In the proposed framework, metadata of the files are stored on the blockchain whereas the actual files are stored off-chain through DHT at multiple locations using a peer-to-peer network of PingER Monitoring Agents. This will provide decentralized storage, distributed processing, and efficient lookup capabilities to the PingER framework.
Francesco Bortolussi, Zeger Hoogeboom, Frank W. Takes
Cryptocurrencies such as Bitcoin and Ethereum have recently gained a lot of popularity, not only as a digital form of currency but also as an investment vehicle. Online marketplaces and exchanges allow users across the world to convert between dozens of different cryptocurrencies and regular currencies such as euros or dollars. Due to the novelty of this concept, the volatility of these markets and the differences in maturity and usage of particular marketplaces, currency pairs may appear at multiple marketplaces but at different trading prices. This paper proposes a novel algorithmic approach to take advantage of these mispricings and capitalize upon the pricing differences that exist between exchanges and currency pairs. To do so, we model each combination of a currency and a market as one node in a graph. A directed link between two nodes indicates that a conversion between these two currency/market pairs is possible. The weight of the link relates to the exchange rate of executing this particular currency exchange. To leverage the mispricings, we seek for cycles in the graph such that upon multiplying the weights of the links in the cycle, a value greater than 1 is found and thus a profit can be made. Our goal is to do this efficiently, without exhaustively enumerating all possible cycles in the graph. Therefore, we convert our data and address the problem in terms of finding minimum weight triangles in graphs with integer weights, for which efficient algorithms can be utilized. We experiment with parameter settings (heuristics) related to the conversion of exchange rate data into integer weight values. We show that our approach improves upon a reasonable baseline algorithm in terms of computation time. Furthermore, using a real-world dataset, we demonstrate how the obtained minimal weight cycles indeed unveil a number of currency exchange cycles that result in a net profit.
Blockchain is an emerging technology that enables new forms of decentralized software architectures, where distributed components can reach agreements on shared system states without trusting a central integration point. Blockchain provides a shared infrastructure to execute programs, called smart contracts, and to store data. Since blockchain technologies are at an early stage, there is a lack of a systematic and holistic view on designing software systems that use blockchain. We view blockchain as part of a bigger system, which requires patterns for using blockchain in the design of their software architecture. In this paper, we collect a list of patterns for blockchain-based applications. The pattern collection is categorized into four types, including interaction with external world patterns, data management patterns, security patterns and contract structural patterns. Some patterns are designed considering the nature of blockchain and how it can be specifically introduced within real-world applications. Others are variants of existing design patterns applied in the context of blockchain-based applications and smart contracts.
Jul 1, 2018·2018 IEEE International Conference on Internet of Things (iThings) and IEEE Green Computing and Communications (GreenCom) and IEEE Cyber, Physical and Social Computing (CPSCom) and IEEE Smart Data (SmartData)
Blockchain-based systems such as cryptocurrencies are achieving widespread usage, with a market capitalization of $150B (USD)as of September 2017. However, the most prominent platforms that account for over 70% of this market - Bitcoin & Ethereum - are exhibiting increasingly lower levels of decentralization. This poses the problem of concentrating levers of consensus to a select group of agents in the system. At the same time, attempts at higher levels of decentralization poses the problem of limiting scalability of such systems. In this paper, using mechanism design we propose a way of designing payoffs in order to disincentivize certain exhibited behaviors and incentivize desired behaviors of miners in such systems. Our approach indicates potential for research in this area for solving the much larger problem of centralization in decentralized systems such as blockchain.
Jul 1, 2018·2018 IEEE International Conference on Internet of Things (iThings) and IEEE Green Computing and Communications (GreenCom) and IEEE Cyber, Physical and Social Computing (CPSCom) and IEEE Smart Data (SmartData)
Readers' capability to consider and assess sources is imperative. Digital preservation efforts, however, mostly neglected citation provenance, which is a necessity for transparent source verification. We therefore present Webchain, a new system enabling verifiable citations and references on the World Wide Web. Its architecture combines a distributed ledger with secure timestamping to ensure history of creation, ownership, and referential integrity of online resources. With Webchain, readers can independently detect content manipulation by verifying authenticity, integrity, and time consistency. At the same time, authors gain a proof of existence for referenced articles. Web-chain extends a well-known distributed timestamping scheme to handle an open and dynamic network topology by providing a solution for membership management. We examine the security of our approach, particularly regarding forging attacks. Our results show that we are able to render such attacks infeasible, even in the face of a powerful attacker.
Jul 1, 2018·2018 IEEE International Conference on Internet of Things (iThings) and IEEE Green Computing and Communications (GreenCom) and IEEE Cyber, Physical and Social Computing (CPSCom) and IEEE Smart Data (SmartData)
Giovanni Di Stasi, Stefano Avallone, Roberto Canonico, Giorgio Ventre
Bitcoin is a new digital currency created with the aim of being decentralized, peer-to-peer, censorship-resistant, borderless, scarce, fast and cheap to use. Since Bitcoin main way of operating is based on broadcast communications, e.g. all transactions of the currency reach all network peers, how to achieve scalability is one of the most important concerns for it to achieve wide usage. One of the proposals to improve its scalability takes the form of the Lightning Network (LN) which consists of an overlay network on top of the base Bitcoin layer. Such an overlay allows to perform a new kind of off-blockchain transactions, i.e. transactions not broadcast to the entire network, that, differently from previous off-blockchain solutions, do not require to put trust in any third entity. Important open problems of the LN are i) defining how payments should be routed and ii) establishing which fee policies intermediate nodes should apply for forwarding payments. The contributions of this work are twofold: we first propose a new, more general, way for nodes to apply fees for forwarding payments which allows to keep the network balanced and improve its performance in the long term. Secondly, we propose a new multipath routing payment scheme, based on the atomic multipath payment method, which is able to significantly reduce the fees paid by users, while being fast and also able to keep the network balanced.
Distributed Ledger Technologies have triggered business model innovation activities among firms. While the available design choices are limited by the unique properties of any protocol, management research so far has neglected the architectural differences between the dominant protocol types. In this study, I analyse the business model design elements of firms seeking to utilise the IOTA Tangle as their underlying DLT protocol for innovation. I identify two potential business model patterns the IOTA Tangle facilitates that is a by-demand logic and the monetisation of data stream. I further find that the IOTA protocol is integrated into open or closed platforms.
Although cryptocurrencies have witnessed explosive growth in the past year, they have also raised many concerns, among which a crucial one is the scalability issue of blockchain-based cryptocurrencies. Suffering from the large overhead of global consensus and security assurance, even leading cryptocurrencies can only handle up to tens of transactions per second, which largely limits their applications in real- world scenarios. Among many proposals to improve cryptocurrency scalability, one of the most promising and mature solutions is the payment channel network (PCN), which offers off-chain settlement of transactions with minimal involvement of expensive blockchain operations. In this paper, we investigate the problem of payment routing in PCN. We suggest crucial design goals in PCN routing, and propose a novel distributed dynamic routing mechanism called CoinExpress. Through extensive simulations, we have shown that our proposed mechanism is able to achieve outstanding payment acceptance ratio with low routing overhead.
Damiano Di Francesco Maesa, Matteo Franceschi, Barbara Guidi, Laura Ricci
Bitcoin has emerged as a disruptive technology able to revolutionize the way financial transactions are performed. The static analysis of the Bitcoin's blockchain conducted jointly with a real time analysis of the Bitcoin's Peer-to-Peer network can reveal interesting properties of the Bitcoin's ecosystem. In this paper we propose BitKer, a Bitcoin kernel client able to interact with the Peer-to-Peer network to retrieve information useful to support higher level analyses. BitKer offers an API to applications requiring an interaction with the underlying network, for instance to implement deanonymization strategies. In this work, we present a first set of experimental results obtained by three different logs, the last one of them obtained just after the August 2017 Bitcoin Cash hard fork. Results show that BitKer is effective in retrieving useful information and can be easily used as a basis for more complex analysis tools.
Mobile peer to peer (P2P) networks offer a huge potential for distributed mobile P2P crowd services (MPCS), which enable data and computational tasks to be offloaded and executed directly between mobile devices. Similar to centralised mobile crowd services, such as mobile crowdsensing, incentivisation mechanisms are core to encouraging mobile users to participate in MPCS systems. However, due to the impact of task execution failures and unreliable behaviours of mobile users (particularly task requesters), it is a daunting task to design and implement an incentivisation mechanism to cater for the needs of MPCS systems. In this paper, we propose a fault-tolerant incentivisation mechanism (FTIM) for MPCS systems. With conditional payment strategies, FTIM is proven to accommodate the requirements of two important application scenarios by achieving mechanism properties such as incentive compatibility, economic efficiency, individual rationality, and weak budget balance. Moreover, to tackle the practical challenges in implementing FTIM in the real world, we design a MPCSTo-ken smart contract to facilitate its service auction, task execution and payment settlement process. We implement the MPCSToken contract on Ethereum blockchain. Both real-world experiment and simulation results show that the system is cost effective for deployments and improves the overall mobile users' utility by exploring the opportunities offered by MPCS.
Jul 1, 2018·2018 IEEE International Conference on Internet of Things (iThings) and IEEE Green Computing and Communications (GreenCom) and IEEE Cyber, Physical and Social Computing (CPSCom) and IEEE Smart Data (SmartData)
Robert Norvill, Beltrán Borja Fiz Pontiveros, Radu State, Andréa Cullen
In this paper we propose a system that moves the bytecode of an Ethereum contract creation transaction off-chain. As blockchains are append-only we present a way to help reduce the chain size and growth for Ethereum. Contract creation transaction data is replaced with hashes which identify a file in InterPlanetary File System (IPFS). Doing so reduces the size of data stored in such transactions by 93.86% in our dataset. The proposed system retains the assurance provided by blockchain and reduces network traffic under certain conditions.
Jul 1, 2018·2018 IEEE International Conference on Internet of Things (iThings) and IEEE Green Computing and Communications (GreenCom) and IEEE Cyber, Physical and Social Computing (CPSCom) and IEEE Smart Data (SmartData)
Distributed Ledger Technology (DLT) allows multiple organizations to share transaction data while protecting data integrity without the need for a central authority. However, there is a strong need to protect the privacy of transactions from parties that are not stakeholders of each transaction. Since DLT is a technology for sharing replicas of the same ledger data across multiple parties, protecting confidentiality and data privacy is essentially difficult. In this paper, we first define the properties of integrity and privacy requirements and discuss the requirements in typical use cases. Finally, we review how the requirements are addressed in existing implementations.
Owing to Satoshi Nakamoto's brilliant idea, a P2P public ledger is shown to be implementable in anonymous network. Any Internet user can then join the anonymous network and contribute to the P2P public ledger by providing their computing power or proof-of-work. The proof-of-work is a clever implementation of one-CPU-one-vote by anonymous participants, and it protects the Bitcoin ledger from illegal modification. To compensate the nodes for their work, a cryptocurrency called Bitcoin is issued and given to nodes. However, the very nature of anonymity of the ledger and the cryptocurrency prevent the technology from being used in fiat money economy. Cryptocurrencies are not traceable even if they are used for money laundering or tax evasion, and the value of cryptocurrencies is not stable but fluctuates wildly. In this white paper, we introduce Gruut, a P2P ledger to implement a universal financial platform for fiat money. For this purpose, we introduce a new consensus algorithm called `proof-of-population,' which is one instance of `proof of public collaboration.' It can be used for multiple purposes; as a P2P ledger for banks, as a powerful tool for payment, including micropayment, and as a tool for any type of financial transactions. Even better, it distributes the profit obtained from transaction fee, currently dominated by a third party, to peers that cannot be centralized. Energy requirements of Gruut are so low that it is possible to run our software on a smartphone or on a personal computer without a graphic card.
David Vangulick, Bertrand Cornélusse, Damien Ernst
Energy communities and peer-to-peer energy exchangesare expected to play an important role in the energy transition. In this context, the blockchain approach can be employed to foster this decentralized energy market. In [1],we evaluated several designs that should allow a Distribution System Operator (DSO) to accept peer-to-peer energyexchanges supported by this technology. This acceptanceis based on criteria such as a strong link with the wholesale/retail market, the resilience of the consensus to approve a block, the accuracy, traceability, privacy and security of the proposed schemes. We concluded that proof-ofstake (PoS), where the choice of node that creates a block isbased on a measure of its wealth, is the only method to fulfill these requirements. In the present paper, we clarify theidentification and estimation of bidding models to ensurethat the PoS that we are developing is a correct responseto two major issues with the PoS methodology, namely theconcentration of wealth and the ”nothing to stake” issue.1
Blockchains have become an integral part of many distributed applications, providing a new platform for interaction between system components. Blockchains are perhaps most known for their use in crypto-currency systems, such as Bitcoin and Ethereum, where pseudo-anonymous parties engage in transactions without a trusted third party. Blockchain systems often struggle to meet performance demands of real-word applications, rendering them inappropriate for performance sensitive applications.\nThere is also concerns regarding the immense amount of electrical energy required to securely run existing public blockchain systems. Bitcoin alone consumes more than small countries. Private systems have higher throughput and avoid excessive energy consumption, but have closed membership and do not scale to the same extent.\n\nBoth public and private blockchains rely on some form of membership mechanism providing peers with a view of other participants. Existing systems often employ partial view protocols due to their natural scalability. However, recent work have shown that full view protocols are feasible in practice, and can scale to thousands of participants. With full membership, applications can send messages directly to their destination without any intermediate hops.\n\nThis thesis presents FireChain, which combines a Byzantine fault-tolerant gossip service and full membership, with a proposal for blockchain systems that does not consume excessive energy. We evaluate FireChain's performance through experiments on PlanetLab, and show that it scales beyond hundreds of members.
Hyunjae Lee, MyungJae Shin, Kyeong Seon Kim, Yeongeun Kang · 5 authors
This paper presents a new approach for avoiding double-spending attacks via the concept of recipient-oriented concepts in private blockchain networks. Together with the concepts of stealth address and masternode at recipient sides, transactional privacy is assured and transaction recipients become active which receive transaction propagation unilaterally. Based on this approach, it can be shown that recipient-oriented method is suggested for preventing the double-spending attacks in this paper. In addition, the proposed method is possible to prevent double spending attacks using the verification time of the recipient and blocking time of the transaction.
Bitcoin, a decentralized P2P cryptocurrency, is the most successful application of blockchain that has gained widespread attention over the past several years. It allows users to create individual transactions and any number of addresses, which is used to send and accept Bitcoin. Generally, the value of Bitcoin is mainly reflected in the degree of users' participation and recognition. In the past, there are many proposed research successfully clustering various addresses into different groups to help identify specific users by using two heuristics. However, they paid little attention to exploit the users' activeness and possible impacts on the development of Bitcoin system. Participation ranking as an indicator is important for enhancing Proof-of-Activity based algorithm and predicting the activity of blockchain system. In this paper, we proposed a model to evaluate users' participation and importance objectively and mechanically by adapting PageRank algorithm. We finally run experiments on the public available metadata of blockchain and compare the results with some well-known addresses to assess its competitiveness.
The Bitcoin protocol, based on a peer-to-peer network enables transactions and blocks to be propagated to all the nodes in a decentralized manner. The information is verified and stored across the nodes as a distributed data ledger, the Blockchain. A node can have a maximum of 8 outgoing connections. The selection of outgoing connections are carried out in a random manner and information is broadcasted to these nodes by flooding. Transaction propagation delays in the network results in temporary inconsistencies in the ledger information resulting in blockchain forks. These can lead to possible double spending attacks. This paper addresses the issue of transaction propagation delay in the network. We present a simulation model of Bitcoin network. The effect of varying the number of outgoing connections and its implication in propagation delay is analyzed to determine the optimum limit of outgoing connections. Further, the idea of selection of nodes based on combination of two parameters, proximity to the sending node and random selection and its effect on transaction propagation delay is explored. Simulation results prove that this method further decreases transaction propagation delay.
Stefano Bistarelli, Ivan Mercanti, Francesco Santini
In Bitcoin, the most common kind of transactions is in the form "Bob pays Alice", and it is based on the Pay to-Public Key Hash (P2PKH) script. P2PKH transactions are just one among many standard classes: a transaction is standard if it passes BitcoinCore's IsStandard() and IsStandardTx() tests. However, the creation of ad-hoc scripts to lock (and unlock) transactions allows for also generating non-standard transactions, which can be nevertheless broadcast and mined as well. In this work, we explore the Bitcoin block-chain with the purpose to analyse and classify standard and non-standard transactions, understanding how much the standard behaviour is respected.
Distributed Ledger (DL) has gained huge attention in the last years and will shift the conduction of business in the future. Until today, because of the great dynamics in the field a systematic approach to structure and define the field of DL does not exist. This led to a heterogeneous landscape of DL definitions and thus, misleading discussions. This paper gives a systematic overview of principles relevant to understand and structure the DL field. Furthermore, based on this it describes DL concepts and shows examples of protocols. The result can then be used for further research but also as a basis for successful collaborations in the field of DL.