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Title:Proof-of-stake longest chain protocols: security vs predicability
Author(s):Wang, Xuechao
Advisor(s):Viswanath, Pramod
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Abstract:The Nakamoto longest chain protocol is remarkably simple and has been proven to provide security against any adversary with less than 50% of the total hashing power. Proof-of-stake (PoS) protocols are an energy-efficient alternative; however existing protocols adopting Nakamoto’s longest chain design achieve provable security only by allowing long-term predictability, subjecting the system to serious bribery attacks. In this thesis, we prove that a natural longest chain PoS protocol with predictability similar to that of Nakamoto’s PoW protocol can achieve security against any adversary with less than 1/(1 +e) fraction of the total stake. Moreover, we propose a new family of longest chain PoS protocols that achieve security against a 50% adversary, while only requiring short-term predictability. Our proofs present a new approach to analyzing the formal security of blockchains, based on a notion of Nakamoto block.
Issue Date:2020-11-16
Rights Information:Copyright 2020 Xuechao Wang
Date Available in IDEALS:2021-03-05
Date Deposited:2020-12

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