A Secure Sharding Protocol For Open Blockchains
24 Oct 2016-pp 17-30
TL;DR: ELASTICO is the first candidate for a secure sharding protocol with presence of byzantine adversaries, and scalability experiments on Amazon EC2 with up to $1, 600$ nodes confirm ELASTICO's theoretical scaling properties.
Abstract: Cryptocurrencies, such as Bitcoin and 250 similar alt-coins, embody at their core a blockchain protocol --- a mechanism for a distributed network of computational nodes to periodically agree on a set of new transactions. Designing a secure blockchain protocol relies on an open challenge in security, that of designing a highly-scalable agreement protocol open to manipulation by byzantine or arbitrarily malicious nodes. Bitcoin's blockchain agreement protocol exhibits security, but does not scale: it processes 3--7 transactions per second at present, irrespective of the available computation capacity at hand. In this paper, we propose a new distributed agreement protocol for permission-less blockchains called ELASTICO. ELASTICO scales transaction rates almost linearly with available computation for mining: the more the computation power in the network, the higher the number of transaction blocks selected per unit time. ELASTICO is efficient in its network messages and tolerates byzantine adversaries of up to one-fourth of the total computational power. Technically, ELASTICO uniformly partitions or parallelizes the mining network (securely) into smaller committees, each of which processes a disjoint set of transactions (or "shards"). While sharding is common in non-byzantine settings, ELASTICO is the first candidate for a secure sharding protocol with presence of byzantine adversaries. Our scalability experiments on Amazon EC2 with up to $1, 600$ nodes confirm ELASTICO's theoretical scaling properties.
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TL;DR: Numerical results indicate that the double auction mechanism can achieve social welfare maximization while protecting privacy of the PHEVs and security analysis shows that the proposed PETCON improves transaction security and privacy protection.
Abstract: We propose a localized peer-to-peer (P2P) electricity trading model for locally buying and selling electricity among plug-in hybrid electric vehicles (PHEVs) in smart grids Unlike traditional schemes, which transport electricity over long distances and through complex electricity transportation meshes, our proposed model achieves demand response by providing incentives to discharging PHEVs to balance local electricity demand out of their own self-interests However, since transaction security and privacy protection issues present serious challenges, we explore a promising consortium blockchain technology to improve transaction security without reliance on a trusted third party A localized P 2P E lectricity T rading system with CO nsortium blockchai N (PETCON) method is proposed to illustrate detailed operations of localized P2P electricity trading Moreover, the electricity pricing and the amount of traded electricity among PHEVs are solved by an iterative double auction mechanism to maximize social welfare in this electricity trading Security analysis shows that our proposed PETCON improves transaction security and privacy protection Numerical results based on a real map of Texas indicate that the double auction mechanism can achieve social welfare maximization while protecting privacy of the PHEVs
933 citations
Cites background from "A Secure Sharding Protocol For Open..."
...Once the authorized LAGs formation is complete and remains almost constant, the total time needed for reaching consensus of one new block is about 1 minute regardless of the network size [13]....
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20 May 2018
TL;DR: OmniLedger ensures security and correctness by using a bias-resistant public-randomness protocol for choosing large, statistically representative shards that process transactions, and by introducing an efficient cross-shard commit protocol that atomically handles transactions affecting multiple shards.
Abstract: Designing a secure permissionless distributed ledger (blockchain) that performs on par with centralized payment processors, such as Visa, is a challenging task. Most existing distributed ledgers are unable to scale-out, i.e., to grow their total processing capacity with the number of validators; and those that do, compromise security or decentralization. We present OmniLedger, a novel scale-out distributed ledger that preserves longterm security under permissionless operation. It ensures security and correctness by using a bias-resistant public-randomness protocol for choosing large, statistically representative shards that process transactions, and by introducing an efficient cross-shard commit protocol that atomically handles transactions affecting multiple shards. OmniLedger also optimizes performance via parallel intra-shard transaction processing, ledger pruning via collectively-signed state blocks, and low-latency "trust-but-verify" validation for low-value transactions. An evaluation of our experimental prototype shows that OmniLedger’s throughput scales linearly in the number of active validators, supporting Visa-level workloads and beyond, while confirming typical transactions in under two seconds.
856 citations
TL;DR: This work exploits the consortium blockchain technology to propose a secure energy trading system named energy blockchain, which can be widely used in general scenarios of P2P energy trading getting rid of a trusted intermediary and a credit-based payment scheme to support fast and frequent energy trading.
Abstract: In industrial Internet of things (IIoT), peer-to-peer (P2P) energy trading ubiquitously takes place in various scenarios, e.g., microgrids, energy harvesting networks, and vehicle-to-grid networks. However, there are common security and privacy challenges caused by untrusted and nontransparent energy markets in these scenarios. To address the security challenges, we exploit the consortium blockchain technology to propose a secure energy trading system named energy blockchain. This energy blockchain can be widely used in general scenarios of P2P energy trading getting rid of a trusted intermediary. Besides, to reduce the transaction limitation resulted from transaction confirmation delays on the energy blockchain, we propose a credit-based payment scheme to support fast and frequent energy trading. An optimal pricing strategy using Stackelberg game for credit-based loans is also proposed. Security analysis and numerical results based on a real dataset illustrate that the proposed energy blockchain and credit-based payment scheme are secure and efficient in IIoT.
778 citations
Cites background from "A Secure Sharding Protocol For Open..."
...The total time needed for reaching consensus of a new block is stable regardless of the network size, when the authorized EAGs formation is complete and remains as a constant [18]....
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TL;DR: This paper conducts a comprehensive evaluation of three major blockchain systems based on BLOCKBENCH, namely Ethereum, Parity, and Hyperledger Fabric, and discusses several research directions for bringing blockchain performance closer to the realm of databases.
Abstract: Blockchain technologies are gaining massive momentum in the last few years. Blockchains are distributed ledgers that enable parties who do not fully trust each other to maintain a set of global states. The parties agree on the existence, values, and histories of the states. As the technology landscape is expanding rapidly, it is both important and challenging to have a firm grasp of what the core technologies have to offer, especially with respect to their data processing capabilities. In this paper, we first survey the state of the art, focusing on private blockchains (in which parties are authenticated). We analyze both in-production and research systems in four dimensions: distributed ledger, cryptography, consensus protocol, and smart contract. We then present BLOCKBENCH, a benchmarking framework for understanding performance of private blockchains against data processing workloads. We conduct a comprehensive evaluation of three major blockchain systems based on BLOCKBENCH, namely Ethereum, Parity, and Hyperledger Fabric. The results demonstrate several trade-offs in the design space, as well as big performance gaps between blockchain and database systems. Drawing from design principles of database systems, we discuss several research directions for bringing blockchain performance closer to the realm of databases.
769 citations
Cites background from "A Secure Sharding Protocol For Open..."
...Other examples are Elastico [26] and Algorand [27] which improve PoW by randomly sampling a small set of nodes at each round....
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...Byzcoin [61] and Elastico [26] propose novel, two-phase protocols that combine PoW and PBFT....
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...Recent work [26] has demonstrated the feasibility of sharding the consensus protocol, making important steps towards partitioning the entire blockchain....
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...Similar to Byzcoin and Elastico, Dfinity [43] and Algorand [27] select at each round a random set of nodes that can propose blocks....
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...Threshold Relay Public Dfinity [43] proposes threshold relay in which nodes form random group based on a public verifiable random function (Byzcoin [61] and Elastico [26] adopt similar approaches)....
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TL;DR: Although the feature of blockchain technologies may bring us more reliable and convenient services, the security issues and challenges behind this innovative technique is also an important topic that the authors need to concern.
Abstract: Blockchain technologies is one of the most popular issue in recent years, it has already changed people's lifestyle in some area due to its great influence on many business or industry, and what it can do will still continue cause impact in many places Although the feature of blockchain technologies may bring us more reliable and convenient services, the security issues and challenges behind this innovative technique is also an important topic that we need to concern
756 citations
Cites background from "A Secure Sharding Protocol For Open..."
...There still have many use case of blockchain technologies, like protection of Intellectual property, traceability in supply chain, identity certification, insurance, international payments, IOT, patient’s privacy in medical treatment or prediction market [14, 20]....
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References
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Posted Content•
TL;DR: The Bitcoin-NG protocol as mentioned in this paper is a new blockchain protocol designed to scale based on Bitcoin's blockchain protocol, which is robust to extreme churn, and shares the same trust model obviating qualitative changes to the ecosystem.
Abstract: Cryptocurrencies, based on and led by Bitcoin, have shown promise as infrastructure for pseudonymous online payments, cheap remittance, trustless digital asset exchange, and smart contracts. However, Bitcoin-derived blockchain protocols have inherent scalability limits that trade-off between throughput and latency and withhold the realization of this potential.
This paper presents Bitcoin-NG, a new blockchain protocol designed to scale. Based on Bitcoin's blockchain protocol, Bitcoin-NG is Byzantine fault tolerant, is robust to extreme churn, and shares the same trust model obviating qualitative changes to the ecosystem.
In addition to Bitcoin-NG, we introduce several novel metrics of interest in quantifying the security and efficiency of Bitcoin-like blockchain protocols. We implement Bitcoin-NG and perform large-scale experiments at 15% the size of the operational Bitcoin system, using unchanged clients of both protocols. These experiments demonstrate that Bitcoin-NG scales optimally, with bandwidth limited only by the capacity of the individual nodes and latency limited only by the propagation time of the network.
761 citations
Posted Content•
TL;DR: This work extracts and analyzes the core of the Bitcoin protocol, which is term the Bitcoin backbone, and proves two of its fundamental properties which are called common prefix and chain quality in the static setting where the number of players remains fixed.
Abstract: Bitcoin is the first and most popular decentralized cryptocurrency to date. In this work, we extract and analyze the core of the Bitcoin protocol, which we term the Bitcoin backbone, and prove two of its fundamental properties which we call common prefix and chain quality in the static setting where the number of players remains fixed. Our proofs hinge on appropriate and novel assumptions on the “hashing power” of the adversary relative to network synchronicity; we show our results to be tight under high synchronization. Next, we propose and analyze applications that can be built “on top” of the backbone protocol, specifically focusing on Byzantine agreement (BA) and on the notion of a public transaction ledger. Regarding BA, we observe that Nakamoto’s suggestion falls short of solving it, and present a simple alternative which works assuming that the adversary’s hashing power is bounded by 1/3. The public transaction ledger captures the essence of Bitcoin’s operation as a cryptocurrency, in the sense that it guarantees the liveness and persistence of committed transactions. Based on this notion we describe and analyze the Bitcoin system as well as a more elaborate BA protocol, proving them secure assuming high network synchronicity and that the adversary’s hashing power is strictly less than 1/2, while the adversarial bound needed for security decreases as the network desynchronizes.
746 citations
Additional excerpts
...4http://tendermint.com/posts/tendermint-vs-pbft/...
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01 Jan 2014
TL;DR: In this paper, the authors propose a new technology, called pegged sidechains, which enables bitcoins and other ledger assets to be transferred between multiple blockchains by reusing Bitcoin's currency, avoiding the liquidity shortages and market fluctuations associated with new currencies.
Abstract: Since the introduction of Bitcoin[Nak09] in 2009, and the multiple computer science and electronic cash innovations it brought, there has been great interest in the potential of decentralised cryptocurrencies. At the same time, implementation changes to the consensuscritical parts of Bitcoin must necessarily be handled very conservatively. As a result, Bitcoin has greater difficulty than other Internet protocols in adapting to new demands and accommodating new innovation. We propose a new technology, pegged sidechains, which enables bitcoins and other ledger assets to be transferred between multiple blockchains. This gives users access to new and innovative cryptocurrency systems using the assets they already own. By reusing Bitcoin’s currency, these systems can more easily interoperate with each other and with Bitcoin, avoiding the liquidity shortages and market fluctuations associated with new currencies. Since sidechains are separate systems, technical and economic innovation is not hindered. Despite bidirectional transferability between Bitcoin and pegged sidechains, they are isolated: in the case of a cryptographic break (or malicious design) in a sidechain, the damage is entirely confined to the sidechain itself. This paper lays out pegged sidechains, their implementation requirements, and the work needed to fully benefit from the future of interconnected blockchains.
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TL;DR: This work presents a novel consensus algorithm that circumvents the requirement that all nodes within the network communicate synchronously by utilizing collectively-trusted subnetworks within the larger network and shows that minimal connectivity is required to maintain agreement throughout the whole network.
Abstract: While several consensus algorithms exist for the Byzantine Generals Problem, specifically as it pertains to distributed payment systems, many suffer from high latency induced by the requirement that all nodes within the network communicate synchronously. In this work, we present a novel consensus algorithm that circumvents this requirement by utilizing collectively-trusted subnetworks within the larger network. We show that the “trust” required of these subnetworks is in fact minimal and can be further reduced with principled choice of the member nodes. In addition, we show that minimal connectivity is required to maintain agreement throughout the whole network. The result is a low-latency consensus algorithm which still maintains robustness in the face of Byzantine failures. We present this algorithm in its embodiment in the Ripple Protocol.
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"A Secure Sharding Protocol For Open..." refers methods in this paper
...Our scalability experiments on Amazon EC2 with up to 1, 600 nodes confirm ELASTICO’s theoretical scaling properties....
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TL;DR: Spanner as mentioned in this paper is Google's scalable, multiversion, globally distributed, and synchronously replicated database, which is the first system to distribute data at global scale and support externally-consistent distributed transactions.
Abstract: Spanner is Google’s scalable, multiversion, globally distributed, and synchronously replicated database. It is the first system to distribute data at global scale and support externally-consistent distributed transactions. This article describes how Spanner is structured, its feature set, the rationale underlying various design decisions, and a novel time API that exposes clock uncertainty. This API and its implementation are critical to supporting external consistency and a variety of powerful features: nonblocking reads in the past, lock-free snapshot transactions, and atomic schema changes, across all of Spanner.
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