Follow blockchain research across journals, conferences, and preprint repositories.
2,350 results · page 88 of 98
Rémi Géraud, David Naccache, Răzvan Roşie
No abstract is available for this record.
Juan A. Garay, Aggelos Kiayias
Consensus is arguably one of the most fundamental problems in distributed computing, playing also an important role in the area of cryptographic protocols as the enabler of a secure broadcast functionality. While the problem has a long and rich history and has been analyzed from many different perspectives, recently, with the advent of blockchain protocols like Bitcoin, it has experienced renewed interest from a much wider community of researchers and has seen its application expand to various novel settings.
Yuki Yamada, Tatsuo Nakajima
No abstract is available for this record.
Waqas Mahmood, Abdul Wahab
Distributed ledger technology has gained wide popularity and adoption since the emergence of bitcoin in 2008 which is based on proof of work (PoW). It is a distributed, transparent and immutable database of records of all the transactions or events that have been shared and executed among the participants. All the transactions are verified and maintained by multiple nodes across a network without a central authority through a distributed cryptographic mechanism, a consensus protocol. It forms the core of this technology that not only validates the information appended to the ledger but also ensures the order in which it is appended across all the nodes. It is the foundation of its security, accountability and trust. While many researchers are working on improving the current protocol to be quantum resistant, fault-tolerant, and energy-efficient. Others are focused on developing different variants of the protocol, best suited for specific use cases. In this paper, we shall review different consensus protocols of distributed ledger technologies and their implementations. We shall also review their properties, concept and similar-work followed by a brief analysis.
Qi Zhang, Petr Novotny, Salman Baset, Donna N. Dillenberger · 6 authors
The rise of crypto-currencies has spawned great interest in their underlying technology, namely, Blockchain. The central component in a Blockchain is a shared distributed ledger. A ledger comprises series of blocks, which in turns contains a series of transactions. An identical copy of the ledger is stored on all nodes in a blockchain network. Maintaining ledger integrity and security is one of the crucial design aspects of any blockchain platform. Thus, there are typically built-in validation mechanisms leveraging cryptography to ensure the validity of incoming blocks before committing them into the ledger. However, a blockchain node may run over an extended period of time, during which the blocks on the disk can may become corrupted due to software or hardware failures, or due to malicious activity. This paper proposes LedgerGuard, a tool to maintain ledger integrity by detecting corrupted blocks and recovering these blocks by synchronizing with rest of the network. The experimental implementation of LedgerGuard is based on Hyperledger Fabric, which is a popular open source permissioned blockchain platform.
Craig Calcaterra, Wulf A. Kaal
No abstract is available for this record.
Kedar Iyer, Chris Dannen
This chapter is the first of our applied practice chapters. It walks through the two fundamental Ethereum interactions. In the first project, we will broadcast a transaction to three Ethereum networks. In the second project, we will deploy a simple Hello World contract.
An Zhang, Kunlong Zhang
No abstract is available for this record.
Matteo Marescotti, Martin Blicha, Antti E. J. Hyvärinen, Sepideh Asadi · 5 authors
No abstract is available for this record.
Leonardo Alt, Christian Reitwießner
No abstract is available for this record.
Pietro Marchionni
No abstract is available for this record.
Michel Rauchs, Andrew Glidden, Brian Gordon, Gina Pieters · 8 authors
The DLT ecosystem is plagued with the use of incomplete and inconsistent definitions and a lack of standardised terminology, creating a needlessly complicated landscape for everyone from experienced policymakers and developers to individuals venturing into the field for the first time. This study sets out to contribute to international discussions to create a shared, common language around DLT systems to clarify terminology and concepts.
Dan Boneh, Benedikt Bünz, Ben Fisch
We present batching techniques for cryptographic accumulators and vector commitments in groups of unknown order. Our techniques are tailored for distributed settings where no trusted accumulator manager exists and updates to the accumulator are processed in batches. We develop techniques for non-interactively aggregating membership proofs that can be verified with a constant number of group operations. We also provide a constant sized batch non-membership proof for a large number of elements. These proofs can be used to build the first positional vector commitment (VC) with constant sized openings and constant sized public parameters. As a core building block for our batching techniques we develop several succinct proof systems in groups of unknown order. These extend a recent construction of a succinct proof of correct exponentiation, and include a succinct proof of knowledge of an integer discrete logarithm between two group elements. We circumvent an impossibility result for Sigma-protocols in these groups by using a short trapdoor-free CRS. We use these new accumulator and vector commitment constructions to design a stateless blockchain, where nodes only need a constant amount of storage in order to participate in consensus. Further, we show how to use these techniques to reduce the size of IOP instantiations, such as STARKs. The full version of the paper is available online [BBF18b].
Rafael Pass, Elaine Shi
No abstract is available for this record.
Bernardo David, Peter Gaži, Aggelos Kiayias, Alexander Russell
No abstract is available for this record.
George Pîrlea, Ilya Sergey
We present the first formalisation of a blockchain-based distributed consensus protocol with a proof of its consistency mechanised in an interactive proof assistant.
Ahmed Abdullah Ali, Iman A. El-Dessouky, Mahmoud Abdallah, Azza K. Nabih
The evolution of the business networks is fostering the demand for more connected devices to execute tangled and sophisticated business operations. This leverages complicated business networks space to include scalable network layers, more devices, and platforms relying on Internet of Things (IoT) solutions. Despite the fact that traditional IoT platforms usually target the technical side for IoT applications, they are not prepared enough to be easily integrated with pluggable and executable business logic or smart contracts. This makes it difficult to control a collection of shared business network resources in a standard and decentralized manner. With the rise of FinTech due to blockchain technology, it becomes possible to seamlessly engage business networks with financial digital assets. Consequently, combining IoT platforms with blockchain will drive new ways for better services consuming, transparency and products that depend on crowd-based economy [12]. In this paper, Sitechain is proposed as a new architecture to integrate IoT platforms with blockchain technology. The proposed architecture is not locked to specific IoT platforms but it can be extended to support different platforms in a standard, systematic and easy way. Sitechain is demonstrated by integrating Sitewhere and FIWARE IoT platforms with Hyperledger Fabric as a private blockchain network manager. Moreover a modeling language supported by Hyperledger composer is used to easily develop smart contracts and generate RESTful APIs, therefore any smart contract transaction events can be mapped into actions on remote devices.
Jong‐Hyouk Lee
Blockchain technology has been known as the underlying technology of cryptocurrencies, but nowadays it is further considered as a functional technology for improving existing technologies and creating new applications previously never practical. In this paper, we are focused on utilizing blockchain technology to introduce a new ID as a service (IDaaS) for digital identity management. The proposed blockchain-based ID as a service (BIDaaS) is explained with one practical example that shows how the proposed BIDaaS works as an identity and authentication management infrastructure for mobile users of a mobile telecommunication company.
Xiangui Wang, Kedan Li, Hui Li, Yinghui Li · 5 authors
Domain name system is an essential component of the Internet, but is facing numerous security threats. On the other hand, blockchain has been widely used since Bitcoin. Theoretically, most of the decentralized system can be rebuilt using blockchain. Namecoin and Blockstack have made attempts to combine domain name service with blockchain, but have defects in security and performance. In this paper, we propose a new domain name service based on a consortium chain network which contains query nodes and miner nodes. To address the storage challenge of blockchain, the system is designed with three-layer architecture and additional external storage. In addition, the system builds index for transactions and blocks to speed up domain name resolution and incorporates gossip protocol to synchronize blocks between different nodes.
Amool Sudhan, Manisha J. Nene
Military operations enabled using networks involves generation, transmission, collection and analysis of mission critical data to enable better decision making capabilities to commanders at all levels to achieve the objectives. This data is generated by variety of heterogeneous elements like humans and equipment in the battlefield. It is of utmost importance to ensure high level of integrity, confidentiality and availability of this data in such an environment and to ensure its sustainability in hostile environments. This paper presents scope and detailed analysis of the idea of utilizing Blockchain technology as a viable solution for ensuring integrity and provenance of data to suit military operations using networks and maintaining sustainability of these networks. The core concepts of Blockchain are presented in a comprehensive manner along with its variations. Military operations enabled using networks are modeled using Network Enabled Military Operations (NEMO) model. The viable framework and architecture for incorporating Blockchain technology to suit security requirements has been analyzed using three case studies relevant in today's scenario.
Zhimin Gao, Lei Xu, Lin Chen, Nolan Shah · 6 authors
Blockchain, or distributed ledger, provides a way to build various decentralized systems without relying on any single trusted party. This is especially attractive for smart contracts, that different parties do not need to trust each other to have a contract, and the distributed ledger can guarantee correct execution of the contract. Most existing distributed ledger based smart contract systems process smart contracts in a serial manner, i.e., all users have to run a contract before its result can be accepted by the system. Although this approach is easy to implement and manage, it is not scalable and greatly limits the system's capability of handling a large number of smart contracts. In order to address this problem, we propose a scalable smart contract execution scheme that can run multiple smart contract in parallel to improve throughput of the system. Our scheme relies on two key techniques: a fair contract partition algorithm leveraging integer linear programming to partition a set of smart contracts into multiple subsets, and a random assignment protocol assigning subsets randomly to a subgroup of users. We prove that, our scheme is secure as long as more than 50% of the computational power is possessed by honest nodes. We then conduct experiments with data from existing smart contract system to evaluate the efficiency of our scheme. The results demonstrate that our approach is scalable and much more efficient than the existing smart contract platform.
Mohammed Ennahbaoui, Hind Idrissi
No abstract is available for this record.
Lucianna Kiffer, Dave Levin, Alan Mislove
As blockchain technologies and cryptocurrencies increase in popularity, their decentralization poses unique challenges in network partitions. In traditional distributed systems, network partitions are generally a result of bugs or connectivity failures; the typical goal of the system designer is to automatically recover from such issues as seamlessly as possible. Blockchain-based systems, however, rely on purposeful "forks" to roll out protocol changes in a decentralized manner. Not all users may agree with proposed changes, and thus forks can persist, leading to permanent network partitions. In this paper, we closely study the large-scale fork that occurred in Ethereum, a new blockchain technology that allows for both currency transactions and smart contracts. Ethereum is currently the second-most-valuable cryptocurrency, with a market capitalization of over $28B. We explore the consequences of this fork, showing the impact on the two networks and their mining pools, and how the fork lead to unintentional incentives and security vulnerabilities.
Shehar Bano, Alberto Sonnino, Mustafa Al-Bassam, Sarah Azouvi · 7 authors
The blockchain initially gained traction in 2008 as the technology underlying bitcoin, but now has been employed in a diverse range of applications and created a global market worth over $150B as of 2017. What distinguishes blockchains from traditional distributed databases is the ability to operate in a decentralized setting without relying on a trusted third party. As such their core technical component is consensus: how to reach agreement among a group of nodes. This has been extensively studied already in the distributed systems community for closed systems, but its application to open blockchains has revitalized the field and led to a plethora of new designs. The inherent complexity of consensus protocols and their rapid and dramatic evolution makes it hard to contextualize the design landscape. We address this challenge by conducting a systematic and comprehensive study of blockchain consensus protocols. After first discussing key themes in classical consensus protocols, we describe: first protocols based on proof-of-work (PoW), second proof-of-X (PoX) protocols that replace PoW with more energy-efficient alternatives, and third hybrid protocols that are compositions or variations of classical consensus protocols. We develop a framework to evaluate their performance, security and design properties, and use it to systematize key themes in the protocol categories described above. This evaluation leads us to identify research gaps and challenges for the community to consider in future research endeavours.