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From: "Russell O'Connor" <roconnor@blockstream.com>
Date: Mon, 11 Jul 2022 16:35:02 -0400
Message-ID: <CAMZUoKmN1Sj=C-asUKCB0hbe-V2fRMsFzNn6kcsJeigbnz3fgQ@mail.gmail.com>
To: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
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Subject: Re: [bitcoin-dev] Security problems with relying on transaction
 fees for security
Precedence: list

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On Mon, Jul 11, 2022 at 2:19 PM Bram Cohen via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> If transaction fees came in at an even rate over time all at the exact
> same level then they work fine for security, acting similarly to fixed
> block rewards. Unfortunately that isn't how it works in the real world.
> There's a very well established day/night cycle with fees going to zero
> overnight and even longer gaps on weekends and holidays. If in the future
> Bitcoin is entirely dependent on fees for security (scheduled very
> strongly) and this pattern keeps up (overwhelmingly likely) then this is
> going to become a serious problem.
>
> What's likely to happen is that at first there will simply be no or very
> few blocks mined overnight. There are likely to be some, as miners at first
> turn off their mining rigs completely overnight then adopt the more
> sophisticated strategy of waiting until there are enough fees in the
> mempool to warrant attempting to make a block and only then doing it.
> Unfortunately the gaming doesn't end there. Eventually the miners with
> lower costs of operation will figure out that they can collectively reorg
> the last hour (or some time period) of the day overnight and this will be
> profitable. That's likely to cause the miners with more expensive
> operations to stop attempting mining the last hour of the day preemptively.
>
> What happens after that I'm not sure.
>

Miners will learn to create anyone-can-spend outputs to bribe other miners
to build on their block rather than reorg it.  (Due to the coinbase
maturity, this will require some amount of floating capital.)

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<div dir=3D"ltr"><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail=
_attr">On Mon, Jul 11, 2022 at 2:19 PM Bram Cohen via bitcoin-dev &lt;<a hr=
ef=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.linux=
foundation.org</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" st=
yle=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padd=
ing-left:1ex"><div dir=3D"ltr">If transaction fees came in at an even rate =
over time all at the exact same level then they work fine for security, act=
ing similarly to fixed block rewards. Unfortunately that isn&#39;t how it w=
orks in the real world. There&#39;s a very well established day/night cycle=
 with fees going to zero overnight and even longer gaps on weekends and hol=
idays. If in the future Bitcoin is entirely dependent on fees for security =
(scheduled very strongly) and this pattern keeps up (overwhelmingly likely)=
 then this is going to become a serious problem.<div><br></div><div>What=
9;s likely to happen is that at first there will simply be no or very few b=
locks mined overnight. There are likely to be some, as miners at first turn=
 off their mining rigs completely overnight then adopt the more sophisticat=
ed strategy of waiting until there are enough fees in the mempool to warran=
t attempting to make a block and only then doing it. Unfortunately the gami=
ng doesn&#39;t end there. Eventually the miners with lower costs of operati=
on will figure out that they can collectively reorg the last hour (or some =
time period) of the day overnight and this will be profitable. That&#39;s l=
ikely to cause the miners with more expensive operations to stop attempting=
 mining the last hour of the day preemptively.=C2=A0</div><div><br></div><d=
iv>What happens after that I&#39;m not sure.<br></div></div></blockquote><d=
iv><br></div><div>Miners will learn to create anyone-can-spend outputs to b=
ribe other miners to build on their block rather than reorg it.=C2=A0 (Due =
to the coinbase maturity, this will require some amount of floating capital=
.)<br></div></div></div>

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