From: Or Sattath <sattath@gmail•com>
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: [bitcoindev] 51% Attack via Difficulty Increase with a Small Quantum Miner
Date: Mon, 18 Mar 2024 06:19:02 -0700 (PDT) [thread overview]
Message-ID: <573ba0d7-522c-424e-898f-caa780c6ecf0n@googlegroups.com> (raw)
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Hi,
In a recent work <https://arxiv.org/abs/2403.08023> with Bolton Bailey
(still not peer-reviewed) , we showed how a single quantum miner, with
relatively little hashing power, can execute a 51% attack. *The attack
isn't relevant for the forthcoming years, requiring an extremely fast,
noise-tolerant quantum computer.*
The attack is surprisingly simple. The attacker creates a private fork,
increasing the difficulty by a factor c. Due to the properties of Grover's
algorithm, it is only \sqrt c harder for the quantum miner to mine at the
new difficulty level, but these blocks count as $c$ times more for the PoW.
Therefore, by mining even a single epoch for a large enough $c$, the
quantum miner can generate more proof-of-work than the competing
(classical) chain. The complexity of the attack is ~1/r^2 epochs, where r
is the fraction of the block rewards that the quantum miner would have
received if they mined honestly. This attack (or variants thereof) provides
essentially the same benefits as classical 51% attacks, including double
spending, and all the revenue from the block rewards.
This attack might be relevant when considering future protocol
modifications.
Or
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next reply other threads:[~2024-03-18 13:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-18 13:19 Or Sattath [this message]
2024-03-20 20:42 ` [bitcoindev] " Antoine Riard
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