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Analysis of Blockchain Consensus.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Analysis of Blockchain Consensus./
作者:	Wang, Ke.
面頁冊數:	1 online resource (153 pages)
附註:	Source: Dissertations Abstracts International, Volume: 83-05, Section: B.
Contained By:	Dissertations Abstracts International83-05B.
標題:	Computer science. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28770657click for full text (PQDT)
ISBN:	9798460483013

Analysis of Blockchain Consensus.
Wang, Ke.

Analysis of Blockchain Consensus. - 1 online resource (153 pages)

Source: Dissertations Abstracts International, Volume: 83-05, Section: B.

Thesis (Ph.D.)--Carnegie Mellon University, 2021.

Includes bibliographical references

Proof of Work (PoW) blockchain is first proposed in Bitcoin. It enables participants to reach consensus in a permissionless setting. Despite its increasing popularity among cryptocurrencies and other applications, the theoretical understanding of PoW blockchains is somewhat incomplete. For instance, existing PoW blockchains adopt a simple k-block confirmation rule. A block is confirmed after it is buried sufficiently deep in the blockchain. The selection of the required depth k is mainly based on empirical experiences. We ask a fundamental question in PoW blockchains: when and how should miners confirm a block in PoW blockchains? We propose the concept of consensus state. A block reaches consensus or is in the consensus state if included in every miner's blockchain. The issue of the existing k-block rule is that it does not depend on consensus. If a block is not in the consensus state when getting confirmed, it is much more likely to be reversed.It is challenging for miners to know the consensus state of a block. A miner needs to check the up-to-date states at every miner to know whether a block reaches consensus. We first present a Consensus-Inference Protocol (CIP) for miners to infer the consensus state locally. Based on CIP, we describe a new Consensus-Aware Confirmation (CAC) rule. A miner does not confirm a block before it infers that block to reach consensus. We analyze the confirmation reversal probability and confirmation latency of the CAC rule. Confirmation latency is the duration from when the miner first observes a block to when the miner confirms that block. Unlike the k-block rule, confirmation latency of the CAC rule depends on how fast blocks reach consensus. We define consensus latency as the duration from when a block is mined to when it reaches consensus. We analyze the consensus latency of PoW blockchains both with and without the adversary. We demonstrate that 1) blocks reach consensus fast and 2) average consensus latency decreases with a higher block rate in practical networks. In many practical scenarios, the CAC rule achieves a much lower reversal probability than the k-block rule with the same confirmation latency. The CAC rule also enables us to configure a higher block rate for better scalability.To further reduce the confirmation reversal probability, we propose a checkpoint protocol. The only reason for block reversal in the CAC rule is that an adversary privately mines on malicious chains. Therefore, we propose a Checkpoint-based Confirmation (CPC) rule. A committee is selected periodically to vote for checkpoint blocks. The checkpoints prevent the adversary from withholding its blocks for too long. Malicious blocks need to be released timely to be referenced by checkpoint blocks. A committee is valid if more than half of the committee members are honest. We show that conditioning on valid committees, miners could consistently achieve 0 confirmation reversal probability. We further show that the assumption of valid committees breaks with negligible probability. Thus, we could always select a proper committee size to ensure the checkpoint-based blockchain functions correctly with extremely high probability.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798460483013Subjects--Topical Terms:

523869
Computer science.
Subjects--Index Terms:

BlockchainIndex Terms--Genre/Form:

542853
Electronic books.

Analysis of Blockchain Consensus.
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500 $a Source: Dissertations Abstracts International, Volume: 83-05, Section: B.
500 $a Advisor: Kim, Hyong S.
502 $a Thesis (Ph.D.)--Carnegie Mellon University, 2021.
504 $a Includes bibliographical references
520 $a Proof of Work (PoW) blockchain is first proposed in Bitcoin. It enables participants to reach consensus in a permissionless setting. Despite its increasing popularity among cryptocurrencies and other applications, the theoretical understanding of PoW blockchains is somewhat incomplete. For instance, existing PoW blockchains adopt a simple k-block confirmation rule. A block is confirmed after it is buried sufficiently deep in the blockchain. The selection of the required depth k is mainly based on empirical experiences. We ask a fundamental question in PoW blockchains: when and how should miners confirm a block in PoW blockchains? We propose the concept of consensus state. A block reaches consensus or is in the consensus state if included in every miner's blockchain. The issue of the existing k-block rule is that it does not depend on consensus. If a block is not in the consensus state when getting confirmed, it is much more likely to be reversed.It is challenging for miners to know the consensus state of a block. A miner needs to check the up-to-date states at every miner to know whether a block reaches consensus. We first present a Consensus-Inference Protocol (CIP) for miners to infer the consensus state locally. Based on CIP, we describe a new Consensus-Aware Confirmation (CAC) rule. A miner does not confirm a block before it infers that block to reach consensus. We analyze the confirmation reversal probability and confirmation latency of the CAC rule. Confirmation latency is the duration from when the miner first observes a block to when the miner confirms that block. Unlike the k-block rule, confirmation latency of the CAC rule depends on how fast blocks reach consensus. We define consensus latency as the duration from when a block is mined to when it reaches consensus. We analyze the consensus latency of PoW blockchains both with and without the adversary. We demonstrate that 1) blocks reach consensus fast and 2) average consensus latency decreases with a higher block rate in practical networks. In many practical scenarios, the CAC rule achieves a much lower reversal probability than the k-block rule with the same confirmation latency. The CAC rule also enables us to configure a higher block rate for better scalability.To further reduce the confirmation reversal probability, we propose a checkpoint protocol. The only reason for block reversal in the CAC rule is that an adversary privately mines on malicious chains. Therefore, we propose a Checkpoint-based Confirmation (CPC) rule. A committee is selected periodically to vote for checkpoint blocks. The checkpoints prevent the adversary from withholding its blocks for too long. Malicious blocks need to be released timely to be referenced by checkpoint blocks. A committee is valid if more than half of the committee members are honest. We show that conditioning on valid committees, miners could consistently achieve 0 confirmation reversal probability. We further show that the assumption of valid committees breaks with negligible probability. Thus, we could always select a proper committee size to ensure the checkpoint-based blockchain functions correctly with extremely high probability.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
650 4 $a Computer science. $3 523869
653 $a Blockchain
653 $a Consensus state
653 $a Performance analysis
653 $a Proof of work blockchain
653 $a Confirmation latency
655 7 $a Electronic books. $2 lcsh $3 542853
690 $a 0984
710 2 $a ProQuest Information and Learning Co. $3 783688
710 2 $a Carnegie Mellon University. $b Electrical and Computer Engineering. $3 2094139
773 0 $t Dissertations Abstracts International $g 83-05B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28770657 $z click for full text (PQDT)