Holger Kinkelin, Valentin Hauner, Heiko Niedermayer, Georg Carle
Numerous IoT applications, like building automation or process control of industrial sites, exist today. These applications inherently have a strong connection to the physical world. Hence, IT security threats cannot only cause problems like data leaks but also safety issues which might harm people. Attacks on IT systems are not only performed by outside attackers but also insiders like administrators. For this reason, we present ongoing work on a Byzantine fault tolerant configuration management system (CMS) that provides control over administrators, restrains their rights, and enforces separation of concerns. We reach this goal by conducting a configuration management process that requires multi-party authorization for critical configurations to prevent individual malicious administrators from performing undesired actions. Only after a configuration has been authorized by multiple experts, it is applied to the targeted devices. For the whole configuration management process, our CMS guarantees accountability and traceability. Lastly, our system is tamper-resistant as we leverage Hyperledger Fabric, which provides a distributed execution environment for our CMS and a blockchain-based distributed ledger that we use to store the configurations. A beneficial side effect of this approach is that our CMS is also suitable to manage configurations for infrastructure shared across different organizations that do not need to trust each other.
Blockchain is a highly popular paradigm for non-centralized applications, especially in finance and trade. Performance is a major challenge for blockchains, since consensus approaches are known not to scale. In this presentation we address blockchain performance, from the perspective of model-based prediction as well as benchmark-based assessment. We present research results about smart contracts in the Ethereum blockchain and discuss the requirements for generic benchmarks for blockchain performance. Benchmarking is a common approach to compare industry-class systems. As blockchain technologies mature, the role of reliable benchmarks will become increasingly important. However, definitions of benchmarks for blockchains are still in their infancy. We argue that there is a clear need for benchmarks, and that benchmarks should be based on the sound scientific principles of metrology [1]. A variety of important performance issues should be addressed, including the performance of the proof (be it work, stake, or other), transaction processing and block creation. Moreover, in all these situations, establishing energy consumption benchmarks is critical in determining if incentives are in place for miners to operate the blockchain system. A particularly interesting element in some blockchains is the mechanism of smart contracts. For instance, in Ethereum, the fees associated with executing contracts depend on the benchmarked performance of the operation code. In [2] it was demonstrated that uncertainty with respect to the correctness of the anticipated execution time impacts the decisions miners will take. We will discuss improved benchmarking approaches for operational code.
Decentralized crypto-currencies based on the blockchain architecture\nunder-utilize available network bandwidth, making them unable to scale to\nthousands of transactions per second. We define the Blockclique architecture,\nthat addresses this limitation by sharding transactions in a block graph with a\nfixed number of threads. The architecture allows the creation of intrinsically\ncompatible blocks in parallel, where each block references one previous block\nof each thread. The consistency of the Blockclique protocol is formally\nestablished in presence of attackers. An experimental evaluation of the\narchitecture's performance in large realistic networks demonstrates an\nefficient use of available bandwidth and a throughput of thousands of\ntransactions per second.\n
Shivika Narang, Praphul Chandra, Shweta Jain, Y. Narahari
The blockchain concept forms the backbone of a new wave technology that promises to be deployed extensively in a wide variety of industrial and societal applications. In this article, we present the scientific foundations and technical strengths of this technology. Our emphasis is on blockchains that go beyond the original application to digital currencies such as bitcoin. We focus on the blockchain data structure and its characteristics; distributed consensus and mining; and different types of blockchain architectures. We conclude with a section on applications in industrial and societal settings, elaborating upon a few applications such as land registry ledger, tamper-proof academic transcripts, crowdfunding, and a supply chain B2B platform. We discuss what we believe are the important challenges in deploying the blockchain technology successfully in real-world settings.
Blockchain serving as an unalterable ledger, has received widespread attentions recently, which allows carrying out transactions with a decentralized matter. Applications with blockchain technology are springing up. However, financial applications especially in bank liquidation system are still facing big challenges. This paper first presents a consensus combined delegated-proof-of-stake protocol and BFT algorithm together. At the same time, using parallel idea and redesigned blockchain structure make the system more efficiency.
JointCloud is a new generation of cloud computing model which facilitates developers to customize cloud services. JCLedger is a blockchain based distributed ledger for JointCloud computing which can make cloud resources exchange more reliable and convenient, and it is the combination of JointCloud and BlockChain. One of the most important elements for creating JCLedger is the consensus algorithm. PoW (Proof of Work) is the consensus algorithm for Bitcoin, which is proved to be quite safe but needs much computing power. The original PoW is not suitable for JCLedger because the identities of participants are not equal in computing power, which may lead to accounting monopoly, and the throughput cannot satisfy the requirement of the massive and high-frequency transactions in JointCloud. In this paper, we propose a PoW based consensus algorithm called Proof of Participation and Fees (PoPF), which can save much computing power and handled transactions more efficiently for JCLedger. In our design, only the candidates have the opportunities for mining and the candidates are chosen according to the ranking which is determined by two factors: the times of the participant to be the accountant and the fees the participant has paid. The difficulty for candidates of solving the PoW hash puzzle is different (the higher ranking means easier for mining). The simulation experiment shows that the distribution of accountants is well-balanced, that is to say, the unequal computing power of participants in JointCloud is shielded, and all the users who have enough contribution in JCLedger will have the opportunities to be accountants.
Blockchains like Bitcoin and Ethereum have seen significant adoption in the past few years and show promise to design applications without any centralized reliance on third parties. In this paper, we present Endolith, an auditing framework for verifying file integrity and tracking file history without third party reliance using a smart contract-based blockchain. Annotated files are continuously monitored and metadata about changes including file hashes are stored tamper-proof on the blockchain. Based on this, Endolith can prove that a file stored a long time ago has not been changed without authorization or, if it did, track when it has changed, by whom. Endolith implementation is based on Ethereum and Hadoop Distributed File System (HDFS). Our evaluation on a public blockchain network shows that Endolith is efficient for files that are infrequently modified but often accessed, which are common characteristics of data archives.
Bitcoin cryptocurrency has risen in popularity. Therefore, it not only attracts users to use it, but also it attracts the malware developers to attack it. While online Bitcoin wallets allow users to conveniently store and manage their bitcoins, they are vulnerable to several attacks.
Sheng Wang, Tien Tuan Anh Dinh, Qian Lin, Zhongle Xie · 10 authors
Existing data storage systems offer a wide range of functionalities to accommodate an equally diverse range of applications. However, new classes of applications have emerged, e.g., blockchain and collaborative analytics, featuring data versioning, fork semantics, tamper-evidence or any combination thereof. They present new opportunities for storage systems to efficiently support such applications by embedding the above requirements into the storage. In this paper, we present ForkBase, a storage engine specifically designed to provide efficient support for blockchain and forkable applications. By integrating the core application properties into the storage, ForkBase not only delivers high performance but also reduces development effort. Data in ForkBase is multi-versioned, and each version uniquely identifies the data content and its history. Two variants of fork semantics are supported in ForkBase to facilitate any collaboration workflows. A novel index structure is introduced to efficiently identify and eliminate duplicate content across data objects. Consequently, ForkBase is not only efficient in performance, but also in space requirement. We demonstrate the performance of ForkBase using three applications: a blockchain platform, a wiki engine and a collaborative analytics application. We conduct extensive experimental evaluation of these applications against respective state-of-the-art system. The results show that ForkBase achieves superior performance while significantly lowering the development cost.
Enterprises have paid attention to blockchain (BC), recently permissioned BC characterized with smart-contract, where business transactions among inter-authorized companies (forming consortium) can automatically be executed based on distributed consensus protocol over user-defined business logics pre-built with program codes. A single BC system will be built across multiple management domains having different operational policies, e.g., datacenter of each organization; this will trigger a problem that its system operations (e.g., backup) will become time-consuming and costly due to the difficulty in unifying and/or adjusting operational policy, schedule, etc. Toward solving the problem, we propose an operations execution method for BC systems; a primary idea is to define operations as smart-contract so that unified and synchronized cross-organizational operations can be executed effectively by using BC-native features. We de-sign the proposed method as hybrid architecture including in-BC consensus establishment and out-BC event-based instruction execution, in order to be adaptable to the recent heterogeneous BC architecture. Performance evaluation using a prototype with Hyperledger Fabric v1.0 shows that the proposed method can start executing operations within 5 seconds. Furthermore, cost evaluation using model-based estimation shows that the total yearly cost of monthly operations on a 5-organizational BC system could be reduced by 61 percent compared to a conventional manual method.
Bitcoin is a peer-to-peer electronic currency without central bank controlling. Nowadays, increasing amount of people are engaged in the mining of Bitcoin for great profits. However, in the Bitcoin system, the more participants in the system, the greater computation power of the whole network and the less efficiency in the output of the coin, since large computational power of the whole Bitcoin system will lead to increased difficulty for a single miner to mine a new data block. At the same time, when more than 51% computing power is controlled by a single node, it could destroy the Bitcoin system. In order to reduce ineffective mining behaviors, one would wish to employ the optimal selection mechanism of different miners. This paper will mainly develop the model in which small miners (those who have relative smaller computational power in a block mining) join the major ones based on revenue, computational power cost, and other elements of the process comparing to the current model (when they work separately).
Lei Xu, Lin Chen, Zhimin Gao, Shouhuai Xu · 5 authors
Public blockchains provide a decentralized method for storing transaction data and have many applications in different sectors. In order for users to track transactions, a simple method is to let them keep a local copy of the entire public ledger. Since the size of the ledger keeps growing, this method becomes increasingly less practical, especially for lightweight users such as IoT devices and smartphones. In order to cope with the problem, several solutions have been proposed to reduce the storage burden. However, existing solutions either achieve a limited storage reduction (e.g., simple payment verification), or rely on some strong security assumption (e.g., the use of trusted server). In this paper, we propose a new approach to solving the problem. Specifically, we propose an \underline{e}fficient verification protocol for \underline{p}ublic \underline{b}lock\underline{c}hains, or EPBC for short. EPBC is particularly suitable for lightweight users, who only need to store a small amount of data that is {\it independent of} the size of the blockchain. We analyze EPBC's performance and security, and discuss its integration with existing public ledger systems. Experimental results confirm that EPBC is practical for lightweight users.
The blockchain technology is a new innovation with the potential to disrupt the\nworld as we currently know it, despite several limitations and challenges to overcome.\nOne of these challenges for software producing organizations is selecting the\nright technology for their case. In this research, we haveve identified this selection\nprocess as a multi-criteria decision making problem. Based on this we have created\na Decision Support System which aids developers during the technology selection\nprocess of blockchain platforms. Contemporary solutions to this problem were only\nrather simplistic decision-trees, which struggle with complexity and adaptations.\nThe novelty of this Decision Support System lies in being a feature-based artifact\nwhich incorporates ISO Software Quality Aspects and feature prioritization based\non the MoSCoW-technique. These contemporary generic blockchain features have\nbeen gathered through nine interviews with blockchain experts. Based on prioritized\nfeatures as input, the Decision Support System gives a score for feasible solutions\n(e.g. Ethereum or Hyperledger) as result. This Decision Support System was\nevaluated in three different case-studies for organization creating blockchain-based\nsolutions. In addition to this, the artifact has been validated by a blockchain-domain\nexpert. The main difficulties and obstacles of this whole research were grounded in\nthe immaturity of the blockchain domain as a whole.
With increasing popularity, the scalability of blockchain-based crypto-currencies becomes an urgent concern. Bitcoin, among other crypto-currencies, have known limitations in transaction throughput and speedbut no agreed upon solution. Many of the proposals increasing throughput also increase the load on the Bitcoin network. Lightning is a proposal enabling payments to be conducted without affecting the Bitcoin network. Lightning is a protocol using payment channels to enable instant and cheap payments using the blockchain for security. With Lightning, payments can be sent through a network of nodes connected by payment channels. In this thesis, the current state of Lightning is explored and an evaluation for use on Bitcoin exchanges is performed. The usability, privacy and security of Lightning are the topics evaluated. In order to evaluate the usability, an exchange interface application was built allowing deposits and withdrawals using Lightning. The protocol specification and relevant literature are examined in order to evaluate the security and privacy of Lightning. The exchange interface showed that Lightning can be integrated into an exchange and provide a fast and cheap way to deposit and withdraw money for clients. In this paper some integration designs are proposed and ways to improve the client user experience are discussed. The Lightning node implementations need to mature a bit before real usage and there are some security issues that also need to be considered. With monitoring and network analysis the privacy can be compromised.
This paper proposes optimization mechanisms for a multi – layered IoT network model, backed up by Blockchain Technology. This paper focuses on optimizing the computational load such that the model can meet the feasible conditions for deployment purpose. Though, dividing the IoT network into multiple layers reduces the computational load at each stage, the load split isn’t quite proportional to the amount of work done at each level. Flexibility to monitor computational load at each level and distribute the workload has been introduced at each level.