Blockchain Papers

Benedikt Putz, Günther Pernul

No abstract is available for this record.

Robin Lamberti, Christian Fries, Markus Lücking, Raphael Manke · 9 authors

No abstract is available for this record.

Mohammad Jabed Morshed Chowdhury, Md Sadek Ferdous, Kamanashis Biswas, Niaz Chowdhury · 7 authors

Distributed Ledger Technology (DLT) has emerged as one of the most disruptive technologies in the last decade. It promises to change the way people do their business, track their products, and manage their personal data. Though the concept of DLT was first implemented in 2009 as Bitcoin, it has gained significant attention only in the past few years. During this time, different DLT enthusiasts and commercial companies have proposed and developed several DLT platforms. These platforms are usually categorized as public vs private, general purpose vs application specific and so on. As a growing number of people are interested to build DLT applications, it is important to understand their underlying architecture and capabilities in order to determine which DLT platform should be leveraged for a specific DLT application. In addition, the platforms need to be evaluated and critically analyzed to assess their applicability, resiliency and sustainability in the long run. In this paper, we have surveyed several leading DLT platforms and evaluated their capabilities based on a number of quantitative and qualitative criteria. The comparative analysis presented in this paper will help the DLT developers and architects to choose the best platform as per their requirement(s).

Jong-Ki Lee, Hwa-Yeol Choi

4차산업혁명 시대는 새로운 도전을 하게 만들었으며, 특히 블록체인 기술은 많은 혁신 기술의 발전을 견인하고, 이제는 블록체인 생태계를 구축하여 많은 사용 사례를 창출하고 일반화되어 가는 기술로 볼 수 있다. 이러한 블록체인 기술을 처리하기 위한 도커 컨테이너(Docker Container) 사용 확산 추세에 발맞추어, 본 연구에서는 도커 컨테이너에 기초한 오픈 소스 하이퍼레저 컴포즈(Hyperledger Composer) 비즈니스 네트워크 구현을 실행하였다. 도커 컨테이너의 환경설정, 커밋 그리고 웹 브라우저를 통한 블록체인 사용 절차를 살펴보고 실제적인 비즈니스 모델을 구현하였다. 본 연구는 도커 컨테이너의 이해, 블록체인 하이퍼레저 컴포저 참여자 및 거래 처리 방법을 구현하고, 실제로 비즈니스 네트워크 블록을 만들어 실행하였다. 이를 통하여 오픈 소스 하이퍼레저 컴포저 블록체인 기술의 근간을 이해하고, 하이퍼레저 컴포즈 블록체인 기술의 사용 확산과 여러 비즈니스 환경에서의 응용에 기여하고자 한다.The era of the fourth industrial revolution has created a new challenge. In particular, the block chain technology has led to the development of many innovative technologies, and now it can be seen as a technology that creates many use cases and becomes generalized by building a block chain ecosystem.  In keep ing with the trend of using Docker Containers to handle these block chain technologies, we have implemented an open source Hyperledger Composer business network based on a Container of Docker. We set up an actual business model by examining the configuration of the container, the commit, and the block chain using the web browser.  Based on the understanding of the Docker Container, this study materialized the block chain Hyperledger Composer participant and transaction processing method, and eventually created and executed the business network block. Through this, we will be able to understand the fundamentals of open source Hyperledger Composer block chain technology and will ultimately contribute to the spread of use of Hyperledger Composer block chain technology and its application in various business environments.

Sergi Delgado-Segura, Surya Bakshi, Cristina Pérez‐Solà, James Litton · 7 authors

Bitcoin relies on a peer-to-peer overlay network to broadcast transactions and blocks. From the viewpoint of network measurement, we would like to observe this topology so we can characterize its performance, fairness and robustness. However, this is difficult because Bitcoin is deliberately designed to hide its topology from onlookers. Knowledge of the topology is not in itself a vulnerability, although it could conceivably help an attacker performing targeted eclipse attacks or to deanonymize transaction senders. In this paper we present TxProbe, a novel technique for reconstructing the Bitcoin network topology. TxProbe makes use of peculiarities in how Bitcoin processes out of order, or "orphaned" transactions. We conducted experiments on Bitcoin testnet that suggest our technique reconstructs topology with precision and recall surpassing 90%. We also used TxProbe to take a snapshot of the Bitcoin testnet in just a few hours. TxProbe may be useful for future measurement campaigns of Bitcoin or other cryptocurrency networks.

Wenbo Jiang, Hongwei Li, Guowen Xu, Mi Wen · 6 authors

Traditional centralized PKIs are vulnerable due to the single point of failure. A feasible solution is to build a decentralized PKI without certificate authority (CA). Web of Trust is the first step toward realizing a decentralized PKI, but it still has some limitations such as missing incentive and leaking user's privacy. Blockchain's numerous desirable properties, such as cryptographical security, decentralized nature and unalterable transaction record, make it a suitable tool to implement a decentralized PKI. However, the latest research findings about blockchain-based PKI are still incompatible with the thin-clients which have limited storage ability to download the entire blockchain. To combat that, we firstly present a Privacy-preserving Thin-client Scheme (PTS) utilizing the idea of k-anonymity, which enables thin-clients to run normally as full node users and protect user's privacy simultaneously. After that, in order to reduce cost, we further propose an Efficient Privacy preserving Thin-client Scheme (EPTS) employing the method of PIR (private information retrieval). Then security analysis and functional comparison are performed to demonstrate the high security and comprehensive functionality of EPTS compared with existing schemes. Finally, extensive experiments are undertaken to confirm that EPTS can reduce computational cost and communication cost impressively.

Srikanta Pradhan, Somanath Tripathy, Sukumar Nandi

Peer to Peer (P2P) is a dynamic and self-organized technology, popularly used in File sharing applications to achieve better performance and avoids single point of failure. The popularity of this network has attracted many attackers framing different attacks including Sybil attack, Routing Table Insertion attack (RTI) and Free Riding. Many mitigation methods are also proposed to defend or reduce the impact of such attacks. However, most of those approaches are protocol specific. In this work, we propose a Blockchain based security framework for P2P network to address such security issues. which can be tailored to any P2P file-sharing system.

Yiming Liu, F. Richard Yu, Xi Li, Hong Ji · 5 authors

By bringing computing capabilities to the network edge, mobile edge computing (MEC) has emerged as a promising technique to enable low-latency video streaming services. However, due to the rapid growth of the number of devices and the heterogeneous formats of the video streams, the traditionally centralized content delivery schemes are insufficient to provide secure, adaptive video services with low complexity. To achieve a decentralized content market among untruthful parties (e.g., users and operators), in this paper, we propose an effective video transcoding and delivery approach based on MEC and blockchain. In the proposed approach, we envision a set of blockchain-based smart contracts to build an autonomous content delivery market, where all the participants are financially enforced by smart contract terms. Then, users, small base stations (SBSs), and content provider (CP) are able to autonomously adjust their strategies according to the content market statistics. Moreover, we formulate the optimization problem, including resource allocation, determining content price and quality levels of contents, as a three-stage Stackelberg game. We analyze the subgame equilibrium for each stage and the interplays of the three-stage game. Lastly, an iterative algorithm is proposed to obtain the solution. Simulation results are presented to show the effectiveness of the proposed approach.

Zhaoyang Yu, Xiaoguang Liu, Gang Wang

Blockchain is a new decentralized and distributed network applying technologies such as P2P network, cryptography and so on, in which P2P lays the foundation. Various consensus mechanisms, which correspond to trust models in P2P, solve the trust problems caused due to the anonymity of nodes. In addition, different incentive models are established in the P2P and blockchain network to encourage nodes to share resources subjectively, thereby improving the contribution of nodes to the system. Based on the analysis of trust and incentive models in P2P, this paper summarizes the consensus and incentive mechanisms of blockchain network. What's more, we indicate the future prospects in blockchain including the improvement of blockchain derived from P2P, the idea of a coin-free blockchain, the problems faced by blockchain, issues about blockchain storage and blockchain application scenarios, which will provide guidance for the future study of blockchain network.

Linxiang Cai, Binjun Wang

Aiming at the problem of illegal activities of Bitcoin, in this paper, transaction data structure of Bitcoin and data storage mechanism of Bitcoin Core (official client for Bitcoin) and are firstly analyzed, then a MapReduce-based structured method for processing transaction data from Bitcoin Core is introduced. Based on above knowledge, mechanisms of tracking and tracing Bitcoin fund flows are proposed, along with the visualization powered by D3.js. This paper provides a practical tool for researching and analyzing flows of illegal transaction funds.

Quanqing Xu, Zhiwen Song, Rick Siow Mong Goh, Yongjun Li

Evolvement of blockchain technology has greatly changed the network and it makes many applications to be distributed, decentralized without loss of security. Ethereum is an open-source blockchain platform that provides a runtime environment for running smart contracts, which is called Ethereum Virtual Machine (EVM). Ethereum-based applications are usually referred to as Decentralized Applications (DApps), since they are based on the decentralized EVM, and its smart contracts. Meanwhile, distributed data store also evolves fast with the blockchain technology. Distributed storage develops to reduce the cost of the server side hardware and increase data availability. InterPlanetary File System (IPFS) is a protocol for distributed storage. IPFS stores immutable data, remove duplication, and obtain address information for storage nodes to search for files in the network. Many DApps have been created with the use of these technologies and one example is to use this design for a decentralized Twitter-like system that is resistant to censorship and single point of failure. This paper involves researching the blockchain technology and implementing a decentralised social network application on the Ethereum private blockchain with the use of smart contract and IPFS. In addition, it examines how blockchain and distributed storage can enable more functionalities of traditional social network systems.

Suman Ghimire, Henry Selvaraj

Bitcoin is a peer-to-peer digital decentralized cryptocurrency created by an individual under pseudonym Satoshi Nakamoto. In fact, it is the first digital decentralized currency. The importance of digital cryptocurrency and the concept of blockchain have been explored by several developers and organizations. It is assumed to be one of the secure and easy payment methods that can be used in the coming days. In this paper, we survey various topics under Bitcoin such as blocks, blockchains, mining process and proof of work(PoW).

Sukrit Kalra, Rishabh Sanghi, Mohan Dhawan

The gaming industry is affected by two key issues---cheating and DDoS attacks against game servers. In this paper, we aim to present a novel yet concrete application of the blockchain technology to address the seemingly disparate problems. Our approach uses blockchain to manage definitive game state and exploits peer consensus on every player action to track modifications to tangible player assets. While a key impediment to adopting blockchain for real-time systems is its high per-operation latency, our approach leverages several optimizations to enable real-time prevention of a large class of cheats where the reported client state is inconsistent with the observed state at the server. Further, blockchain-based games leverage the robust peer-to-peer architecture to successfully defend against DDoS attacks.

F. Schüßler, Pezhman Nasirifard, Hans‐Arno Jacobsen

Despite the very high volatility of the cryptocurrency markets, the interest in the development and adaptation of existing cryptocurrencies such as Bitcoin as well as new distributed ledger technologies is increasing. Therefore, understanding the security and vulnerability issues of such blockchain systems plays a critical role. In this work, we propose a configurable distributed simulation framework for analyzing Bitcoin-like blockchain systems which are based on Proof-of-Work protocols. The simulator facilitates investigating security properties of blockchain systems by enabling users to configure several characteristics of the blockchain network and executing different attack scenarios, such as double-spending attacks and flood attacks and observing the effects of the attacks on the blockchain network.

Mohamed Riswan Abdul Lathif, Pezhman Nasirifard, Hans‐Arno Jacobsen

Directed Acyclic Graph (DAG) based Distributed Ledger Technologies (DLT) such as IOTA Tangle has been proposed to address the inefficiencies of traditional blockchains, including the issues with scalability, high resource consumptions, and the increasing transaction fees. Despite the promising features introduced by IOTA, the properties of DAG-based distributed ledgers are not yet comprehensively studied. In this work, we propose CIDDS, a configurable and interactive DAG-based DLT simulation framework. CIDDS enables the user to perform large-scale simulations with thousands of nodes and to investigate different characteristics of the network under controlled conditions.

Ryosuke Abe, Shigeya Suzuki, Jun Murai

A type of Bitcoin node called "Full Node" has to hold the entire of historical transaction data called "Blockchain" to verify that new transactions are correct or not. To operate nodes as Full Nodes, the required storage size will be too large for resource-constrained devices. In this paper, to mitigate storage size, we propose a storage load balancing scheme by distributed storage based on Distributed Hash Table (DHT). By our scheme, nodes in a DHT cluster can behave like Full Nodes without holding the entire of the blockchain.

Magdalena Punceva, Haute Ecole Arc, Ninoslav Marina

Cryptocurrency exchange platforms, which have appeared recently, provide exchanges between different types of cryptocurrencies as well as fiat money. Since multiple exchange platforms exist today, it is of essential importance to have timely information about user experience and the behavior of participants in such platforms. Trust is a notion that has been studied extensively in sociology, psychology, economics and computer science, with an objective to provide measures for quantifying user behavior in specific social settings and contexts. While in the domain of online social networks, the trust has been thoroughly analyzed from various points of view, in cryptocurrency exchange platforms, the questions about quantifying the levels of emerging trust, are still open. In this work, we elaborate on quantifying trust in the context of cryptocurrency exchange platforms. We focus on two well known bitcoin exchange platforms: Bitcoin-OTC and Bitcoin-Alpha. Using the existing data about user ratings upon interactions in these two platforms, we show how trust is related with the network structure and how to identify communities where trust level is high among participants. Our results can serve as a basis for a strategy on how to interact within these platforms.

Alexander Yakubov, Wazen M. Shbair, Nida Khan, Radu State · 6 authors

Pretty Good Privacy (PGP) is one of the most prominent cryptographic standards offering end-to-end encryption for email messages and other sensitive information. PGP allows to verify the identity of the correspondent in information exchange as well as the information integrity. PGP implements asymmetric encryption with certificates shared through a network of PGP key servers. Many recent breaches show that certificate infrastructure can be compromised as well as exposed to operational errors. In this paper we propose a new PGP management framework with the key server infrastructure implemented using blockchain technology. Our framework resolves some problems of PGP key servers focusing in particular on fast propagation of certificate revocation among key servers and elimination of man-in-the-middle risk. We also provided user access right control where only the certificate holder can change information related to the certificate. We designed and developed a prototype for key server deployment on permissioned Ethereum blockchain. Permissioned blockchain should allow to control the costs of PGP key server infrastructure maintenance at the present level.

Kaneko Yudai, Takuya Asaka

Blockchain technology which is the fundamental system of Bitcoin running on a peer-to-peer (P2P) network, has attracted a lot of attention. This enables a practical P2P electronic money system with Byzantine fault tolerance and stability with all participating nodes having the same transaction ledger and using a distributed consensus algorithm called Proof of Work (PoW) that performs calculation work called mining. Many studies have proposed methods of enhancing scalability in terms of transaction processing of blockchain, however few studies have proposed them in term of network load in a P2P network architecture. To solve these problems, we propose a method in which all nodes are separated into mining nodes in a pure P2P network and blockchain data having nodes in a distributed hash table (DHT) network. Kademlia is incorporated as DHT network for processing responsible blocks' data for each node cluster and broadcasting efficiently. The results of a broadcast simulation show that our method improved the redundancy rate and average number of messages in the networks.

Ella Tallyn, Larissa Pschetz, Rory Gianni, Chris Speed · 5 authors

Technologies such as distributed ledgers and smart contracts are enabling the emergence of new autonomous systems, and providing enhanced systems to track the provenance of goods. A growing body of work in HCI is exploring the novel challenges of these systems, but there has been little attention paid to their impact on everyday activities. This paper presents a study carried out in 3 office environments for a 1-month period, which explored the impact of an autonomous coffee machine on the everyday activity of coffee consumption. The Bitbarista mediates coffee consumption through autonomous processes, presenting provenance data at the time of purchase while attempting to reduce intermediaries in the coffee trade. Through the report of interactions with and around the Bitbarista, we explore its implications for everyday life, and wider social structures and values. We conclude by offering recommendations for the design of community shared autonomous systems.

Frédérique Oggier, Silivanxay Phetsouvanh, Anwitaman Datta

We showcase a graph mining tool, BiVA, for visualization and analysis of the Bitcoin network. It enables data exploration, visualization of subgraphs around nodes of interest, and integrates both standard and new algorithms, including a general algorithm for flow based clustering for directed graphs, and other Bitcoin network specific wallet address aggregation mechanisms. The BiVA user interface makes it easy to get started with a basic visualization that gives insights into nodes of interests, and the tool is modular, allowing easy integration of new algorithms. Its functionalities are demonstrated with a case study of extortion of Ashley Madison data breach victims.

Ajay Kumar Shrestha, Julita Vassileva

Blockchains were originally used to support the Bitcoin cryptocurrency and now entire software ecosystems are being supported by blockchains. Despite their widespread use, not much is known about how peers in the bitcoin blockchain network use the system. We present visualizations to help in identifying some patterns in the usage of bitcoin blockchain supported technologies. In this paper, we observe the bitcoin transaction continent-wise via a visualization of the locations from where peers in the bitcoin blockchain network were making their transactions, using WebGL technology. We analyzed regional bitcoin blockchain usage patterns by observing their clusters formation over time. We also presented a pattern of how the value of the bitcoin changes over time.

Lucianna Kiffer, Dave Levin, Alan Mislove

Ethereum is the second most valuable cryptocurrency today, with a current market cap of over $68B. What sets Ethereum apart from other cryptocurrencies is that it uses the blockchain to not only store a record of transactions, but also smart contracts and a history of calls made to those contracts. Thus, Ethereum represents a new form of distributed system: one where users can implement contracts that can provide functionality such as voting protocols, crowdfunding projects, betting agreements, and many more. However, despite the massive investment, little is known about how contracts in Ethereum are actually created and used.

Seoung Kyun Kim, Zane Ma, Siddharth Murali, Joshua Mason · 6 authors

Ethereum, the second-largest cryptocurrency valued at a peak of $138 billion in 2018, is a decentralized, Turing-complete computing platform. Although the stability and security of Ethereum---and blockchain systems in general---have been widely-studied, most analysis has focused on application level features of these systems such as cryptographic mining challenges, smart contract semantics, or block mining operators. Little attention has been paid to the underlying peer-to-peer (P2P) networks that are responsible for information propagation and that enable blockchain consensus. In this work, we develop NodeFinder to measure this previously opaque network at scale and illuminate the properties of its nodes. We analyze the Ethereum network from two vantage points: a three-month long view of nodes on the P2P network, and a single day snapshot of the Ethereum Mainnet peers. We uncover a noisy DEVp2p ecosystem in which fewer than half of all nodes contribute to the Ethereum Mainnet. Through a comparison with other previously studied P2P networks including BitTorrent, Gnutella, and Bitcoin, we find that Ethereum differs in both network size and geographical distribution.