51% Attack via Difficulty Increase with a Small Quantum Miner

Fuente: arXiv
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Autores principales: Bailey, Bolton, Sattath, Or
Formato: Preprint
Publicado: 2024
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author Bailey, Bolton
Sattath, Or
author_facet Bailey, Bolton
Sattath, Or
contents We present a strategy for a single quantum miner with relatively low hashing power, with the same ramifications as a 51% attack. Bitcoin nodes consider the chain with the highest cumulative proof-of-work to be the valid chain. A quantum miner can manipulate the block timestamps to multiply the difficulty by $c$. The fork-choice rule counts every block with increased difficulty with weight $c$. By using Grover's algorithm, it is only $O(\sqrt c)$ harder for the quantum miner to mine such blocks. By picking a high enough $c$, the single quantum miner can create a competing chain with fewer blocks, but more cumulative proof-of-work. The time required is $O(\frac{1}{r^2})$ epochs, where $r$ is the fraction of the block rewards that the quantum miner would have received if they mined honestly. Most proof-of-work cryptocurrencies, including Bitcoin, are vulnerable to our attack. However, it will likely be impossible to execute in forthcoming years, as it requires an extremely fast and fault-tolerant quantum computer.
format Preprint
id arxiv_https___arxiv_org_abs_2403_08023
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle 51% Attack via Difficulty Increase with a Small Quantum Miner
Bailey, Bolton
Sattath, Or
Quantum Physics
Cryptography and Security
We present a strategy for a single quantum miner with relatively low hashing power, with the same ramifications as a 51% attack. Bitcoin nodes consider the chain with the highest cumulative proof-of-work to be the valid chain. A quantum miner can manipulate the block timestamps to multiply the difficulty by $c$. The fork-choice rule counts every block with increased difficulty with weight $c$. By using Grover's algorithm, it is only $O(\sqrt c)$ harder for the quantum miner to mine such blocks. By picking a high enough $c$, the single quantum miner can create a competing chain with fewer blocks, but more cumulative proof-of-work. The time required is $O(\frac{1}{r^2})$ epochs, where $r$ is the fraction of the block rewards that the quantum miner would have received if they mined honestly. Most proof-of-work cryptocurrencies, including Bitcoin, are vulnerable to our attack. However, it will likely be impossible to execute in forthcoming years, as it requires an extremely fast and fault-tolerant quantum computer.
title 51% Attack via Difficulty Increase with a Small Quantum Miner
topic Quantum Physics
Cryptography and Security
url https://arxiv.org/abs/2403.08023