From: Jeremy Rubin <jeremy.l.rubin@gmail•com>
To: Bitcoin development mailing list <bitcoin-dev@lists•linuxfoundation.org>
Subject: [bitcoin-dev] Does Bitcoin require or have an honest majority or a rational one? (re rbf)
Date: Sun, 16 Oct 2022 13:35:54 -0400 [thread overview]
Message-ID: <CAD5xwhjXh33AdK96eToHtDP3t_Zx5JbxCqJFbAQRRRKy6rFC2Q@mail.gmail.com> (raw)
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The Bitcoin white paper says:
The proof-of-work also solves the problem of determining representation in
majority decision
making. If the majority were based on one-IP-address-one-vote, it could be
subverted by anyone
able to allocate many IPs. Proof-of-work is essentially one-CPU-one-vote.
The majority
decision is represented by the longest chain, which has the greatest
proof-of-work effort invested
in it. If a majority of CPU power is controlled by honest nodes, the honest
chain will grow the
fastest and outpace any competing chains. To modify a past block, an
attacker would have to
redo the proof-of-work of the block and all blocks after it and then catch
up with and surpass the
work of the honest nodes. We will show later that the probability of a
slower attacker catching up
diminishes exponentially as subsequent blocks are added.
This, Satoshi (who doesn't really matter anyways I guess?) claimed that for
Bitcoin to function properly you need a majority honest nodes.
There are multiple behaviors one can describe as honest, and economically
rational or optimizing is not necessarily rational.
For example, if I run a shop that takes rain checks, but I sell an item to
a higher bidder who didn't have a hold on the item, that is not honest, but
it may be selfish profit maximizing.
Satoshi said an honest majority is required for the chain to be extended.
Honest is not really defined though. Honesty, in my definition, is that you
follow a pre specified rule, rational or not.
It seems a lot of the RBF controversy is that Protocol developers have
aspired to make the honest behavior also be the rational behavior. This is
maybe a good idea because, in theory, if the honest behavior is rational
then we can make a weaker assumption of selfishness maximizing a parameter.
However, Satoshi did not particularly bound what aspects of honesty are
important for the network, because there isn't a spec defining exactly what
is honest or not. And also as soon as people are honest, you can rely on
that assumption for good effect.
And sometimes, defining an honest behavior can be creating a higher utility
system because most people are "law abiding citizens" who might not be
short term rational. For example, one might expect that miners would be
interested in making sure lightning closes are "accurate" because
increasing the utility of lightning is good for Bitcoin, even if it is
irrational.
It seems that the NoRBF crowd want to rely on an honest majority assumption
where the honest behavior is not doing replacement if not requested. This
is really not much different than trying to close lightning channels "the
right way".
However, where it may be different, is that even in the presence of honest
majority, the safety of 0conf isn't assured given the potential of race
conditions in the mempool. Therefore it's not clear to me that 0conf
working well is something you can drive from the Honest Majority Assumption
(where honest includes first seen).
Overall, it might be nice to more tightly document what bitcoins
assumptions are in practice and what those assumptions do in terms of
properties of Bitcoin, as well as pathways to weakening the assumptions
without compromising the behaviors users expect the network to have. An
"extended white paper" if you will.
It's somewhat clear to me that we shouldn't weaken assumptions that only
seem local to one subsystem of Bitcoin if they end up destabilizing another
system. In particular, things that decrease "transaction utility" for end
users decrease the demand for transactions which hurts the fee market's
longer term viability, even if we feel good about making an honest policy
assumption into a self interested policy assumption.
A last reflection is that Bitcoin is specified with an honest majority
assumption, but also has a rational dishonest minority assumption over both
endogenous (rewards) and exogenous (electricity) costs. Satoshi did not
suggest, at least as I read it, that Bitcoin works with an rational
majority assumption. (If anyone thinks these three are similar properties
you can make some trivial counterexamples)
Cheers,
Jeremy
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next reply other threads:[~2022-10-16 17:36 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-16 17:35 Jeremy Rubin [this message]
2022-10-16 19:03 ` email
2022-10-17 19:10 ` Jeremy Rubin
2022-10-17 22:31 ` email
2022-10-18 3:34 ` Jeremy Rubin
2022-10-18 14:30 ` Russell O'Connor
2022-10-18 16:27 ` Jeremy Rubin
2022-10-18 17:33 ` Erik Aronesty
2022-10-18 18:57 ` email
2022-10-20 19:21 ` email
2022-10-20 22:19 ` Peter Todd
2022-10-17 15:51 ` Russell O'Connor
2022-10-17 19:02 ` Jeremy Rubin
2022-10-20 22:28 ` Peter Todd
2022-10-20 23:54 ` Jeremy Rubin
2022-10-21 0:26 ` Peter Todd
2022-10-21 8:47 ` email
2022-10-21 13:17 ` S kang
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