Paper 2020/601

Everything is a Race and Nakamoto Always Wins

Amir Dembo, Sreeram Kannan, Ertem Nusret Tas, David Tse, Pramod Viswanath, Xuechao Wang, and Ofer Zeitouni


Nakamoto invented the longest chain protocol, and claimed its security by analyzing the private double-spend attack, a race between the adversary and the honest nodes to grow a longer chain. But is it the worst attack? We answer the question in the affirmative for three classes of longest chain protocols, designed for different consensus models: 1) Nakamoto's original Proof-of-Work protocol; 2) Ouroboros and SnowWhite Proof-of-Stake protocols; 3) Chia Proof-of-Space protocol. As a consequence, exact characterization of the maximum tolerable adversary power is obtained for each protocol as a function of the average block time normalized by the network delay. The security analysis of these protocols is performed in a unified manner by a novel method of reducing all attacks to a race between the adversary and the honest nodes.

Note: A shorter version of this paper will appear in the 2020 ACM Conference on Computer and Communications Security (CCS).

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Published elsewhere. Arxiv
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nusret @ stanford edu
2020-08-30: last of 3 revisions
2020-05-22: received
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      author = {Amir Dembo and Sreeram Kannan and Ertem Nusret Tas and David Tse and Pramod Viswanath and Xuechao Wang and Ofer Zeitouni},
      title = {Everything is a Race and Nakamoto Always Wins},
      howpublished = {Cryptology ePrint Archive, Paper 2020/601},
      year = {2020},
      note = {\url{}},
      url = {}
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