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003			ISI Library, Kolkata
005			20240920111033.0
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040			_aISI Library _bEnglish
082	0	4	_223 _a332.1780285582 _bM475
100	1		_aSubhra Mazumdar _eauthor
245	1	0	_aSecure off-chain transactions in blockchain-based payment channel networks/ _cSubhra Mazumdar
260			_aKolkata: _bIndian Statistical Institute, _c2022
300			_a187 pages,
502			_aThesis (Ph. D.) - Indian Statistical Insitute, 2022
504			_aIncludes bibliography
505	0		_aIntroduction -- Preliminaries and Background -- Literature Survey -- HushRelay: A Scalable Routing Algorithm for Off-Chain Payments -- CryptoMaze: Privacy-Preserving Splitting of Off-Chain Payments -- Griefing-penalty: Countermeasure for Griefing Attack in Lightning Network -- Strategic Analysis of Griefing Attack in Lightning Network
508			_aGuided by Prof. Sushmita Ruj and Prof. Bimal Kumar Roy
520			_aCryptocurrencies enable users to execute a financial transaction without relying on any third party. The use of Blockchain technology guarantees the security and immutability of transactions. Despite these features, blockchain-based financial transactions fail to compete with conventional payment systems like Visa, and PayPal, in terms of scalability. Layer 2 protocols built on top of blockchain solve the scaling difficulties that are faced by the major cryptocurrency networks. Payment Channel Network or PCN is one of the most widely deployed layer 2 protocols. Users are allowed to execute off-chain payments, leading to high throughput. PCN relies on the underlying blockchain for security. After studying the literature, we observed that routing and payment in PCN are the two most challenging tasks. The network is susceptible to attacks where malicious players can intentionally stall payments and eliminate their competitors from the network. In this thesis, we propose an efficient privacy-preserving distributed routing algorithm HushRelay. Experimental analysis shows that our proposed routing algorithm has a higher success ratio and lower execution time compared to the state-of-the-art. Given a set of routes, we propose an atomic and privacy-preserving multi-path payment protocol, CryptoMaze. No honest intermediary loses funds in the process, ensuring balance security. We observe that CryptoMaze is quite efficient and the communication overhead is within feasible bounds. We discuss the griefing attack, a major vulnerability in Bitcoin’s PCN, and propose an efficient countermeasure for the attack, termed Griefing-Penalty. The penalty charged compensates parties who incurred loss by locking funds. We propose a new payment protocol HTLC-GP or Hashed Timelock Contract with Griefing-Penalty that demonstrates the utility of the countermeasure. Finally, we have analyzed griefing attacks in the network from a game-theoretic point of view and observed that HTLC-GP is weakly effective in disincentivizing the attacker in certain conditions. To further increase the cost of attack, we introduce the concept of guaranteed minimum compensation and integrate it into HTLC-GP. This modified payment protocol, HTLC-GP⇣ , considers the participants to act rationally. By experimenting on several real instances of PCN, we observed that HTLC-GP⇣ is better than HTLC-GP to counter griefing attacks.
650		4	_aBanking Services _xComputer Applications
650		4	_aSecure Off-Chain Transactions _xAlgorithms
650		4	_aBlockchain-Based Transactions _xCryptographic Applications
650		4	_aPayment Channel Networks _xCryptoMaze
650		4	_aFinancial Transactions _xBlockchain Technology _vCryptocurrencies
856			_uhttp://dspace.isical.ac.in:8080/jspui/handle/10263/7350 _yFull Text
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