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arXiv · 2308.11379

Colordag: An Incentive-Compatible Blockchain

Ittai Abraham·Danny Dolev·Ittay Eyal·Joseph Y. Halpern
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Abstract

We present Colordag, a blockchain protocol where following the prescribed strategy is, with high probability, a best response as long as all miners have less than 1/2 of the mining power. We prove the correctness of Colordag even if there is an extremely powerful adversary who knows future actions of the scheduler: specifically, when agents will generate blocks and when messages will arrive. The state-of-the-art protocol, Fruitchain, is an epsilon-Nash equilibrium as long as all miners have less than 1/2 of the mining power. However, there is a simple deviation that guarantees that deviators are never worse off than they would be by following Fruitchain, and can sometimes do better. Thus, agents are motivated to deviate. Colordag implements a solution concept that we call epsilon-sure Nash equilibrium and does not suffer from this problem. Because it is an epsilon-sure Nash equilibrium, Colordag is an epsilon Nash equilibrium and with probability (1 - epsilon) is a best response.

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Ittai Abraham, Danny Dolev, Ittay Eyal, Joseph Y. Halpern. 2023-08-22. Colordag: An Incentive-Compatible Blockchain. https://arxiv.org/abs/2308.11379

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