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From: Marc Bevand <m.bevand@gmail.com>
To: Robert Taylor <roberttaylorgen@gmail.com>,
	 Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Centralizing mining by force
Date: Wed, 08 Nov 2017 05:04:07 +0000	[thread overview]
Message-ID: <CADH-5r3YqvO4rbS5PEc86LB-CGsrMnARUj7Vbfi0opBB_EuMQA@mail.gmail.com> (raw)
In-Reply-To: <CAArA6tURLo0yiM+js=KJEo8i1FTwOKV7V+qjC8yGd8q2PgvewQ@mail.gmail.com>

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What you describe is an example of a majority attack ("51% attack"). No
technical mechanism in Bitcoin prevents this. However in practice, miners
are not incentivized to perform this attack as it would destroy confidence
in Bitcoin, and would ultimately impact their revenues.

-Marc

On Mon, Nov 6, 2017, 22:32 Robert Taylor via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> Forgive me if this has been asked elsewhere before, but I am trying to
> understand a potential failure mode of Bitcoin mining.
>
> A majority of miners can decide which valid blocks extend the chain. But
> what would happen if a majority of miners, in the form of a cartel decided
> to validly orphan any blocks made by miners outside of their group? For
> example, they could soft fork a new rule where the block number is signed
> by set of keys known only to the cartel, and that signature placed in the
> coinbase. Miners outside of the cartel would not be able to extend the
> chain.
>
> It would be immediately obvious but still valid under the consensus rules.
> What are the disincentives for such behavior and what countermeasures could
> be done to stop it and ensure mining remained permissionless? I think this
> is a valid concern because while it may not be feasible for one actor to
> gain a majority of hash alone, it is certainly possible with collusion.
>
> Robert
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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  reply	other threads:[~2017-11-08  5:04 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-07  3:55 [bitcoin-dev] Centralizing mining by force Robert Taylor
2017-11-08  5:04 ` Marc Bevand [this message]
2017-11-09 18:18   ` Eric Voskuil
2017-11-08  5:37 ` ZmnSCPxj

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