The rapid advance of Blockchain has been used for the Internet-of-Things to provide reliable distributed infrastructure and applications without a centralized authority. This paper aims to create a new consensus protocol that can be efficiently and resiliently used for the Internet-of-Things based on the Practical Byzantine Fault Tolerance algorithm (PBFT), which is critical for IoT scalability and reliability. The traditional PBFT algorithm fails to provide two significant features: a) resiliency against denial of service (DoS) attacks, and b) high-throughput to quickly reach final consensus when under attack. This paper analyzes the current implementation of PBFT consensus protocol and proposes a new secure approach for achieving consensus by adding the properties of random hash generation and threshold comparison in order to defend against DoS attacks.
Most people first encounter blockchain technology by way of cryptocurrencies like Bitcoin. Bitcoin came into existence during the start of the 2008 financial crisis and was first disclosed in October 2008.1Because of the timing and some clear indicators embedded into the first (genesis) block of Bitcoin, we know that a primary reason for developing cryptocurrency was a distrust of large institutions that control the worldâs fiat currencies. However, what does currency have to do with media technology?
We try to verify properties of the Bitcoin-S library, a Scala implementation of parts of the Bitcoin protocol. We use the Stainless verifier which supports programs in a fragment of Scala called Pure Scala. Since Bitcoin-S is not written in this fragment, we extract the relevant code from it and rewrite it until we arrive at code that we successfully verify. In that process we find and fix two bugs in Bitcoin-S.
We propose a sociotechnical, yet computational, approach to building decentralized applications that accommodates and exploits blockchain technology. Our architecture incorporates the notion of a declarative, violable contract and enables flexible governance based on formal organizational structures, correctness verification without obstructing autonomy, and a basis for trust.
PaweĹ ĹniataĹa, M. Hadi Amini, Kianoosh G. Boroojeni
Information fusion has been a topic of immense interest owing to its applicability in various applications. This brings to the fore the need for a flexible and accurate fusion algorithm that can be versatile. The BrooksâIyengar algorithm is one such fusion algorithm. It has since its inception found numerous applications that deal with the fusion of data from multiple sources. The uniqueness of the BrooksâIyengar algorithm is the ease with which the data from multiple sensors in a local system can be fused and also reach consensus in a distributed system with the added capability of fault tolerance. Blockchain has found its use as a distributed ledger and has successfully supported and fueled many crypto-currencies over the years. Information fusion with regard to blockchains is a topic of great research interest in the past couple of years. Since blockchain has no official node, the introduction of a decentralized network and a consensus algorithm is required in making the interactions and exchanges between multiple suppliers easier and thus leads to business being carried out without any hassles. In this paper, we attempt to understand and describe the deployment of multiple sensors to measure various aspects of the physical world. We discuss a novel technique of employing the BrooksâIyengar algorithm in the design of the system that would decentralize the data source from the corresponding measurements and thus ensure the integrity of the transactions in the blockchain. Finally, a theoretical analysis of the performance of the algorithm when used in a blockchain based decentralized environment is also discussed.
Open access
Distributed systems and fault tolerance
Distributed Sensor Networks and Detection Algorithms
Blockchain's popularity has seen a historic rise over the last decade. However, existing blockchain systems have a major issue with scalability, which has become one of the main obstacles in technology's adoption in mainstream. There have been several attempts to address this limitation by identifying Blockchain's scalability/performance bottlenecks (e.g. those mainly related to consensus algorithms), and thus proposed different solutions (e.g., new consensus protocols) to address such limitations. Other works applied sharding to tackle the issue. All solutions however have mainly focused on Cryptocurrency applications, and thus addressing the scalability of blockchain systems for general applications remains a concern. This work proposes a scalable blockchain protocol for general applications (i.e., not restricted to Cryptocurrencies). To improve the two major factors affecting transaction scalability, namely throughput and latency, we needed to modify both the blockchain structure as well as the block generation process. ZyConChain, the proposed Blockchain system, introduces three types of blocks that form three separate chains: parentBlock, sideBlock and state block. These blocks are generated based on different consensus algorithms, as each algorithm has specific properties that make it suitable for each type of block. To improve the overall performance, ZyConChain generates sideBlocks (that carry transactions) at a high rate and keep them in a pool. To generate parentBlock, miners, instead of packing transactions into a block as they do in conventional blockchains, pack sideBlocks into a parentBlock. SideBlocks are generated based on an adapted Zyzzyva consensus protocol, with O(\log n) complexity. This has reduced the final consensus complexity per transaction, in comparison to previous work. To enable the protocol to scale out with the increase in the number of nodes, ZyConChain applied sharding technique. Parallel state chains have also been introduced to address cross-shard transactions.
BlaĹž Podgorelec, Marjan Herieko, Muhamed TurkanoviÄ
Currently, developers and researchers are dedicated to finding better ways to achieve greater scalability of various blockchain platforms. Focused on the Ethereum blockchain platform, the state channels are currently the only maturely researched and implemented a solution for achieving scalability. However, there are still several problems, such as transparency of state channel networks, transaction traceability, and the incapability that the off-chain state is transferred back on the blockchain network in an ad-hoc manner. To solve the aforementioned problems, we propose a novel state channel solution in the form of a State Channel as a Service, which, although off-chain, still incorporates a secure distributed and decentralized network. This solves the challenge of transparency and traceability while giving users the confidence that only the valid last off-chain state is transferred back on the blockchain network. With the proposed solution, there is no need for users to monitor state channel activities for possible malicious actions. Implementation was performed in the form of a payment channel system, presenting a potential use case for the SCaaS. Furthermore, we performed a security and performance analysis, which shows that the solution is secure and by a factor of 12 more efficient than the classical on-chain payment systems. To evaluate and prove the contributions of the proposed solution, quantitative, and qualitative comparisons with selected related works (i.e., Raiden and Celer) were also performed.
The main incentives of blockchain technology are distribution and distributed change, consistency, and consensus. Beyond just being a distributed ledger for digital currency, smart contracts add transaction protocols to blockchains to execute terms of a contract in a blockchain network. Inter-blockchain (IBC) protocols define and control exchanges between different blockchains.
The Isabelle Infrastructure framework has been designed to serve security and privacy for IoT architectures by formal specification and stepwise attack analysis and refinement. A major case study of this framework is a distributed health care scenario for data consistency for GDPR compliance. This application led to the development of an abstract system specification of blockchains for IoT infrastructures.
In this paper, we first give a summary of the concept of IBC. We then introduce an instantiation of the Isabelle Infrastructure framework to model blockchains. Based on this we extend this model to instantiate different blockchains and formalize IBC protocols. We prove the concept by defining the generic property of global consistency and prove it in Isabelle.
Soohyeong Kim, Sejong ÂLee, C. Jeong, Sunghyun Cho
Blockchain is a distributed, reliable, and secure ledger that maintains data by consensus among network participants. The consensus algorithms provide data reliability but increase the data processing time. In this paper, we propose the multi-block consensus algorithm based on Byzantine Fault Tolerance to enhance throughput. The key point of the proposed algorithm is that the primary propagates the disjoint-transaction sets to other replicas. After receiving the propagated blocks, the replicas verify the propagation part and the content part of the blocks. As sharing the verifying result, the replicas could add the valid blocks to the blockchain at a time. We evaluate the performance of the proposed algorithm comparing to the Practical Byzantine Fault Tolerance algorithm which is the most ordinary Byzantine Fault Tolerance based algorithm. By the simulation results, throughput increases as the number of users increases.
The commercial utilization of cryptocurrency as a digital asset in being more and more sought-after on each successive year. Most of the well-renowned crypto platforms nowadays are devised based on the premise of the concept of blockchain. These cryptocurrencies work as an alternative medium of exchange using cryptography to secure the transactions on a distributed ledger. When using regular blockchain-based digital cryptocurrency most of the time the respected crypto-platforms discourage low valued microtransactions from being executed. Because often, the transaction fee may exceed the value of the product or service that is being purchased. As a result, for this particular reason, micropayment systems using digital crypto platforms remain largely underdeveloped. To solve this complication our thesis model was emanated from the notion of IOTA, which is considered as a minerless crypto-platform where the requisition of miners is disregarded thus enabling users to relish the advantages of microtransactions, however with the inclusion of âDiscretionary miningâ. âDiscretionary Miningâ refers to the hypothesis of the availability of mining capabilities at the discretion of the users.