[Bitcoin-segwit2x] Strong 2-Way Replay Protection

hubert maslin hubert.maslin at gmail.com
Tue Oct 10 09:32:20 UTC 2017

I get your frustration that the ecosystem resists a lot to something that's
a no-brainer upgrade for you, but this resistance is a feature, not a bug,
and in my opinion Segwit2X was the wrong vehicle to achieve an upgrade of
this kind from the beginning.

Bitcoin is not an enterprise database that your supplier can upgrade in a
week, it's a *shared* global decentralised ledger, it's an infrastructure
used by millions (and hopefully billions in the future) of people who all
have their own reasons to use it and their own preferences. It's to be
expected by upgrading such a thing will be a long and contentious process.

If you want the support of developers, investors and power users, you have
to make this 2X base block size (now block weight) increase palatable to
them, by asking them whether they might to see some other changes bundled
with it, and also by having enough time to develop, test and deploy the
fork (for example 6 months for development/testing and a year for
deployment). Replay protection is also a must, so that those whose wishes
haven't been fulfilled by the fork can easily stay on their chain, without
feeling like they're marginalised, or held hostages.

I know this isn't a psychology or anthropology mailing list, but I'd like
to make a point about human nature, that explains why debates get so heated
so easily.
People don't like to back down to so much as the smallest slights or
disrespect, because of the implicit assumption that such a retreat would
only lead to greater agression or disrespect in the future - this is why
violent conflicts often arise from seemingly benign squabbles. This
assumption is literally built in us; it's a by-product of our evolution,
because those humans who reacted to threats of agression instead of waiting
for an actual agression to take place might have had better odds of
survival. Suppose that we do as you wish and agree on this fork: what tells
us that a year from now some other group of CEOs will not come up with a
perfectly valid reason to implement address blacklisting at the protocol
level, or change Bitcoin's inflation schedule? Having backed down to the
November 2017 2X hard fork would make it harder for us to resist the ones
to come.
The fact that we mistrust people whose objectives and group membership
differ from ours is a truth as fundamental as the fact that we breathe, eat
or drink. To disarm this natural mistrust, the process that leads to the
definition and implementation of the fork has to be as inclusive,
egalitarian and open as possible, so that all voices can be heard. The
process might actually matters even more than its own product - the fork
design - because the process itself is an expression of the balance of
economic power among the different stakeholders; and it would be dangerous
to artificially sway this balance through manipulation, disinformation or

You refer to the risk of the hard fork being small. But focusing on pure
technical risks misses the point: the main risk of this fork (and the main
reason why so many of us are opposed to it) is the fact that it opens the
door to further contentious changes in the future. There's an element of
recursion here - the fork is contentious because it sets a bad precedent of
a contentious change having been made -  and that's because the design
process it stems from wasn't open and collaborative.

You can't get together at a private meeting (from what I've understood,
developers other than those closely affiliated to you weren't invited),
agree among yourselves to redesign Bitcoin and expect other stakeholders to
follow you. It's sad that Segwit2X chose that path, because many early
adopters and investors are realistic and understand that a block weight
increase will very likely be needed in the future, because even if we could
get a large part of the bitcoin economy to use paiement channels, we would
still have to have enough room to settle them.

I'm afraid it's too late to call off the fork, as you've all already
invested so much time and energy in it. I think (and hope) that the fork
will fail, and that the B2X chain will never gain any significant economic
value - precisely because it would be so vulnerable to arbitrary changes in
consensus rules from external actors.

In any case I hope that the next iterations of the scaling debate will be
more open and collaborative, and see cool heads prevail.


2017-10-09 22:27 GMT+02:00 Mike Belshe <mike at bitgo.com>:

> Thanks for the lengthy reply.  Your argument can go both ways; why not
> support this 2mb block size increase?  The risk has already been mitigated
> - miners will adopt it, businesses will support it, and its compatible with
> 99.5% of existing wallets. Now, if the core team would start trying to help
> it work, instead of fighting it for pride and emotional reasons, we'd even
> have all the developer support behind it....   There are no technical
> arguments remaining against it - just lengthy prose about misunderstandings
> and what not.
> You imply that planning for growth/scalability has a correlated risk of
> destabilization that accompanies it.  If we took that as our guiding
> principle, we wouldn't implement segwit either.  Sure, segwit is opt-in at
> the user level, but its not opt-in at the chain level - we all are
> dependent on it working properly or the chain which we share breaks for all
> of us. The 2x part of Segwit2x is, by any measure, a simpler technical
> change.   I would never say that changes carry no risk, but as far as risk
> goes, this one is really small.
> It's a good opportunity now to just move to 2mb blocks, and there are
> literally no technical objections left.
> Mike
> On Mon, Oct 9, 2017 at 9:58 AM, hubert maslin via Bitcoin-segwit2x <
> bitcoin-segwit2x at lists.linuxfoundation.org> wrote:
>> Hello Mike, I understand that you're meaning well and want, as we all do,
>> bitcoin to succeed over long term, and by reading your messages on this
>> thread I've once again noticed that the current rift within the Bitcoin
>> community actually springs from a few disagreements that have more to do
>> with culture and process rather than with long term goals. I'm going to
>> talk about those disagreements and hopefully state the "pro
>> decentralisation" position in a way that's conducive to intelligent debate
>> and perhaps, ultimate agreement.
>> We want to bring Bitcoin to more users because it has unique features and
>> qualities (namely permissionless-ness, resistance to tx censorship,
>> resistance to inflation, pseudonymity) that the existing financial system
>> doesn't offer. The presence of these features is contrary to the interests
>> of many powerful entities (the legacy banking system, governments and their
>> surveillance agencies) and only survive thanks to Bitcoin's
>> decentralisation and absence of centralised points of failure. Being
>> willing to sacrifice or endanger Bitcoin's decentralisation to achieve
>> scaling isn't wise or forward thinking, and is completely self-defeating.
>> What's the point of on-boarding an ever greater number of users if you run
>> the risk of weakening those features and give those users the same
>> experience than current centralised paiement systems offer, e.g. tx
>> censorship, vulnerability to inflation, and government surveillance? This
>> would be a nonsensical and unproductive thing to do.
>> Doing this would be all the more absurd that we now know (as we have
>> since 2015) that, before increasing base block size, we can greatly
>> increase throughput through more efficient of block space (with Segwit and,
>> in the near future, with MAST, Schnorr signatures and signatures
>> aggregation) and more importantly, with second layer technologies such as
>> the Lightning Network or sidechains. These technologies are under rapid
>> development, and will soon alleviate scaling.
>> Presenting the scaling debate as a dichotomy between "onboard users fast
>> and break things" and "let's for ever stay a store of value for rich
>> people" is a mistake, because we know we can already greatly improve
>> scaling, within the next few months and years. Was scaling slower than
>> anticipated, we should err on the side of caution, and not give our
>> potential adversaries any lever that they might pull to weaken those
>> features.
>> And this is why this scheduled hard fork worries me. Regardless of the
>> blockchain bloating issue, changing consensus rules without wide community
>> consensus - and in particular without the consensus of the community
>> members that value decentralisation and privacy the most - is precisely
>> such a lever for governments or other antagonists to pull.
>> It would set an extremely bad precedent. The particulars of this fork -
>> the fact that it doesn't have replay protection, that it lays a claim on
>> the Bitcoin brand, that it relies on the imperfect security models of SPV
>> wallets to make them follow new consensus rules - make things worse.
>> if this fork is successful and the entire community shifts to the S2X
>> chain (which, barring a prolonged 51% attack on the original chain, seems
>> extremely unlikely to me), this would signals to external actors that
>> consensus rules can be changed by exercising the right pressure on the
>> right companies - and we're literally talking of a dozen mining pools and a
>> dozen major paiement processors and exchanges, spread in only a few
>> jurisdictions. This would cast doubt on the entire ability of
>> cryptocurrencies to remain decentralised and act as censorship-resistant
>> medium of exchange and inflation-resistant store of value. Bitcoin's sole
>> comparative advantage over centralised systems would vanish.
>> Even if this fork wasn't a base block size doubling but a simple,
>> symbolic increase of one byte to base block size, it would still be a bad
>> thing, because it would show that consensus rules - and therefore the very
>> nature of the currency people use - can be changed by external actors. To
>> me and to many other people, this debate isn't about block size anymore:
>> it's about the survivability of Bitcoin as a decentralised system. The
>> Bitcoin community should be as amorphous and resistant to change as
>> possible - even to more technically sound changes like Segwit, and even
>> when these changes come from competent devs with a solid track record of
>> defending decentralisation and privacy.
>> Just because only a few thousands or dozens of thousands of early users
>> and cypherpunks out of a dozen million of users disagree with this fork
>> doesn't mean we can be ignored: Bitcoin rose to its current popularity (and
>> value) because we invested our time, our hopes and our money in it, and
>> millions of politically unresponsive BitPay or Coinbase customers will not
>> make up for our absence on a centralised chain.
>> Claiming that Segwit2X has consensus with the now standard line "those
>> who oppose it are only a few thousands, while NYA signatories have millions
>> of customers" is akin to the NSA claiming that a majority of citizens
>> endorses surveillance, "because only a few thousands nerds care about it".
>> Claiming the silence of a majority of stakeholders as a tacit endorsement
>> of some policy is a dangerous (and I would add immoral) thing to do, and is
>> what has led to the creation of the centralised institutions that Bitcoin
>> aims at replacing.
>> Bitcoin is a formidable opportunity to bring greater monetary, economic
>> and political freedom to all humans, and the single best hope of
>> freedom-loving persons in this otherwise authoritarian and freedom-hating
>> century. Regardless of whatever understanding or sympathy we may have for
>> you and other NYA signatories, we who care about those things can not
>> accept cooptation by companies who effectively are centralised points of
>> failure at the mercy of governments.
>> If I could sum up my position (and the position of many users preoccupied
>> with decentralisation), it would be: "let us scale wisely, without making
>> short-term compromises that would weaken Bitcoin's unique features". Merely
>> increasing base block size as soon as we lack space would be akin to
>> kicking the can down the road to serfdom. And changing consensus rules at a
>> whim - or worse, engaging in a 51% attack to coerce the community into
>> following the new rules - would get us there in no time.
>> And to respond to one of your points, Mike, wishing for both chains to
>> survive is certainly not about "pride": it's about giving a durable,
>> decentralised consensus system to the world, a system that can't be
>> coopted, coerced or censored.
>> Mike, if you have any question or wish to continue this chat privately
>> feel free to respond directly to this email. I feel that the differences
>> between our respective camps are born out of cultural differences and
>> absurd misunderstandings, and magnified by our good ol' tribal instincts;
>> there is no reason why we should go through a messy divorce when we all
>> agree on making Bitcoin the world's sole currency, used for both small
>> purchases and storing large amount of values. This is Bitcoin's destiny,
>> and our squabbles are petty in comparison.
>> Cheers.
>> Hubert
>> _______________________________________________
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>> Bitcoin-segwit2x at lists.linuxfoundation.org
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> --
> *Mike Belshe*
> *CEO, BitGo, Inc*408-718-6885 <(408)%20718-6885>
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