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From: Chris Riley <criley@gmail.com>
Date: Sun, 16 Mar 2025 14:03:36 -0400
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Subject: Re: [bitcoindev] Against Allowing Quantum Recovery of Bitcoin
To: Jameson Lopp <jameson.lopp@gmail.com>
Cc: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
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This makes a lot of sense.  One would think that prior to an attack on
bitcoin other coins would be attacked first, e.g. Ethereum given the way I
understand that public keys are exposed vs bitcoin, so there could be some
warning from softer, vulnerable and valuable targets to attack such as alt
coins, governments, and financial institutions.

However, none of this changes the points you made and the importance of
looking at the issue sooner versus later given the long lead time that will
be necessary since there could be little warning.  I have seen estimates in
the 2030-2035 range for a potential attack and the US Federal government
tells agencies they must transition by 2035 to a quantum safe scheme
further emphasizing the potential urgency.

Of course, some argue it could take "decades" or even longer=E2=80=94if it =
ever
happens at all=E2=80=94so there is significant uncertainty about when a suc=
cessful
attack might occur. To me, this is a "prepare for the worst and hope for
the best" scenario. As you noted, whether coins are "burned" or "stolen,"
the outcome is the same for their owners: they lose control of their
assets. Logically, they might even prefer for their coins to be burned
rather than stolen, as it would prevent dilution of any remaining holdings
and help mitigate systemic damage to the ecosystem.

Thanks :-)


On Sun, Mar 16, 2025 at 11:22=E2=80=AFAM Jameson Lopp <jameson.lopp@gmail.c=
om>
wrote:

> The quantum computing debate is heating up. There are many controversial
> aspects to this debate, including whether or not quantum computers will
> ever actually become a practical threat.
>
> I won't tread into the unanswerable question of how worried we should be
> about quantum computers. I think it's far from a crisis, but given the
> difficulty in changing Bitcoin it's worth starting to seriously discuss.
> Today I wish to focus on a philosophical quandary related to one of the
> decisions that would need to be made if and when we implement a quantum
> safe signature scheme.
>
> Several Scenarios
> Because this essay will reference game theory a fair amount, and there ar=
e
> many variables at play that could change the nature of the game, I think
> it's important to clarify the possible scenarios up front.
>
> 1. Quantum computing never materializes, never becomes a threat, and thus
> everything discussed in this essay is moot.
> 2. A quantum computing threat materializes suddenly and Bitcoin does not
> have quantum safe signatures as part of the protocol. In this scenario it
> would likely make the points below moot because Bitcoin would be
> fundamentally broken and it would take far too long to upgrade the
> protocol, wallet software, and migrate user funds in order to restore
> confidence in the network.
> 3. Quantum computing advances slowly enough that we come to consensus
> about how to upgrade Bitcoin and post quantum security has been minimally
> adopted by the time an attacker appears.
> 4. Quantum computing advances slowly enough that we come to consensus
> about how to upgrade Bitcoin and post quantum security has been highly
> adopted by the time an attacker appears.
>
> For the purposes of this post, I'm envisioning being in situation 3 or 4.
>
> To Freeze or not to Freeze?
> I've started seeing more people weighing in on what is likely the most
> contentious aspect of how a quantum resistance upgrade should be handled =
in
> terms of migrating user funds. Should quantum vulnerable funds be left op=
en
> to be swept by anyone with a sufficiently powerful quantum computer OR
> should they be permanently locked?
>
> "I don't see why old coins should be confiscated. The better option is to
>> let those with quantum computers free up old coins. While this might hav=
e
>> an inflationary impact on bitcoin's price, to use a turn of phrase, the
>> inflation is transitory. Those with low time preference should support
>> returning lost coins to circulation."
>
> - Hunter Beast
>
>
> On the other hand:
>
> "Of course they have to be confiscated. If and when (and that's a big if)
>> the existence of a cryptography-breaking QC becomes a credible threat, t=
he
>> Bitcoin ecosystem has no other option than softforking out the ability t=
o
>> spend from signature schemes (including ECDSA and BIP340) that are
>> vulnerable to QCs. The alternative is that millions of BTC become
>> vulnerable to theft; I cannot see how the currency can maintain any valu=
e
>> at all in such a setting. And this affects everyone; even those which
>> diligently moved their coins to PQC-protected schemes."
>> - Pieter Wuille
>
>
> I don't think "confiscation" is the most precise term to use, as the fund=
s
> are not being seized and reassigned. Rather, what we're really discussing
> would be better described as "burning" - placing the funds *out of reach
> of everyone*.
>
> Not freezing user funds is one of Bitcoin's inviolable properties.
> However, if quantum computing becomes a threat to Bitcoin's elliptic curv=
e
> cryptography, *an inviolable property of Bitcoin will be violated one way
> or another*.
>
> Fundamental Properties at Risk
> 5 years ago I attempted to comprehensively categorize all of Bitcoin's
> fundamental properties that give it value.
> https://nakamoto.com/what-are-the-key-properties-of-bitcoin/
>
> The particular properties in play with regard to this issue seem to be:
>
> *Censorship Resistance* - No one should have the power to prevent others
> from using their bitcoin or interacting with the network.
>
> *Forward Compatibility* - changing the rules such that certain valid
> transactions become invalid could undermine confidence in the protocol.
>
> *Conservatism* - Users should not be expected to be highly responsive to
> system issues.
>
> As a result of the above principles, we have developed a strong meme
> (kudos to Andreas Antonopoulos) that goes as follows:
>
> Not your keys, not your coins.
>
>
> I posit that the corollary to this principle is:
>
> Your keys, only your coins.
>
>
> A quantum capable entity breaks the corollary of this foundational
> principle. We secure our bitcoin with the mathematical probabilities
> related to extremely large random numbers. Your funds are only secure
> because truly random large numbers should not be guessable or discoverabl=
e
> by anyone else in the world.
>
> This is the principle behind the motto *vires in numeris* - strength in
> numbers. In a world with quantum enabled adversaries, this principle is
> null and void for many types of cryptography, including the elliptic curv=
e
> digital signatures used in Bitcoin.
>
> Who is at Risk?
> There has long been a narrative that Satoshi's coins and others from the
> Satoshi era of P2PK locking scripts that exposed the public key directly =
on
> the blockchain will be those that get scooped up by a quantum "miner." Bu=
t
> unfortunately it's not that simple. If I had a powerful quantum computer,
> which coins would I target? I'd go to the Bitcoin rich list and find the
> wallets that have exposed their public keys due to re-using addresses tha=
t
> have previously been spent from. You can easily find them at
> https://bitinfocharts.com/top-100-richest-bitcoin-addresses.html
>
> Note that a few of these wallets, like Bitfinex / Kraken / Tether, would
> be slightly harder to crack because they are multisig wallets. So a quant=
um
> attacker would need to reverse engineer 2 keys for Kraken or 3 for Bitfin=
ex
> / Tether in order to spend funds. But many are single signature.
>
> Point being, it's not only the really old lost BTC that are at risk to a
> quantum enabled adversary, at least at time of writing. If we add a quant=
um
> safe signature scheme, we should expect those wallets to be some of the
> first to upgrade given their incentives.
>
> The Ethical Dilemma: Quantifying Harm
> Which decision results in the most harm?
>
> By making quantum vulnerable funds unspendable we potentially harm some
> Bitcoin users who were not paying attention and neglected to migrate thei=
r
> funds to a quantum safe locking script. This violates the "conservativism=
"
> principle stated earlier. On the flip side, we prevent those funds plus f=
ar
> more lost funds from falling into the hands of the few privileged folks w=
ho
> gain early access to quantum computers.
>
> By leaving quantum vulnerable funds available to spend, the same set of
> users who would otherwise have funds frozen are likely to see them stolen=
.
> And many early adopters who lost their keys will eventually see their
> unreachable funds scooped up by a quantum enabled adversary.
>
> Imagine, for example, being James Howells, who accidentally threw away a
> hard drive with 8,000 BTC on it, currently worth over $600M USD. He has
> spent a decade trying to retrieve it from the landfill where he knows it'=
s
> buried, but can't get permission to excavate. I suspect that, given the
> choice, he'd prefer those funds be permanently frozen rather than fall in=
to
> someone else's possession - I know I would.
>
> Allowing a quantum computer to access lost funds doesn't make those users
> any worse off than they were before, however it *would* have a negative
> impact upon everyone who is currently holding bitcoin.
>
> It's prudent to expect significant economic disruption if large amounts o=
f
> coins fall into new hands. Since a quantum computer is going to have a
> massive up front cost, expect those behind it to desire to recoup their
> investment. We also know from experience that when someone suddenly finds
> themselves in possession of 9+ figures worth of highly liquid assets, the=
y
> tend to diversify into other things by selling.
>
> Allowing quantum recovery of bitcoin is *tantamount to wealth
> redistribution*. What we'd be allowing is for bitcoin to be redistributed
> from those who are ignorant of quantum computers to those who have won th=
e
> technological race to acquire quantum computers. It's hard to see a brigh=
t
> side to that scenario.
>
> Is Quantum Recovery Good for Anyone?
>
> Does quantum recovery HELP anyone? I've yet to come across an argument
> that it's a net positive in any way. It certainly doesn't add any securit=
y
> to the network. If anything, it greatly decreases the security of the
> network by allowing funds to be claimed by those who did not earn them.
>
> But wait, you may be thinking, wouldn't quantum "miners" have earned thei=
r
> coins by all the work and resources invested in building a quantum
> computer? I suppose, in the same sense that a burglar earns their spoils =
by
> the resources they invest into surveilling targets and learning the skill=
s
> needed to break into buildings. What I say "earned" I mean through
> productive mutual trade.
>
> For example:
>
> * Investors earn BTC by trading for other currencies.
> * Merchants earn BTC by trading for goods and services.
> * Miners earn BTC by trading thermodynamic security.
> * Quantum miners don't trade anything, they are vampires feeding upon the
> system.
>
> There's no reason to believe that allowing quantum adversaries to recover
> vulnerable bitcoin will be of benefit to anyone other than the select few
> organizations that win the technological arms race to build the first suc=
h
> computers. Probably nation states and/or the top few largest tech compani=
es.
>
> One could certainly hope that an organization with quantum supremacy is
> benevolent and acts in a "white hat" manner to return lost coins to their
> owners, but that's incredibly optimistic and foolish to rely upon. Such a
> situation creates an insurmountable ethical dilemma of only recovering lo=
st
> bitcoin rather than currently owned bitcoin. There's no way to precisely
> differentiate between the two; anyone can claim to have lost their bitcoi=
n
> but if they have lost their keys then proving they ever had the keys
> becomes rather difficult. I imagine that any such white hat recovery
> efforts would have to rely upon attestations from trusted third parties
> like exchanges.
>
> Even if the first actor with quantum supremacy is benevolent, we must
> assume the technology could fall into adversarial hands and thus think
> adversarially about the potential worst case outcomes. Imagine, for
> example, that North Korea continues scooping up billions of dollars from
> hacking crypto exchanges and decides to invest some of those proceeds int=
o
> building a quantum computer for the biggest payday ever...
>
> Downsides to Allowing Quantum Recovery
> Let's think through an exhaustive list of pros and cons for allowing or
> preventing the seizure of funds by a quantum adversary.
>
> Historical Precedent
> Previous protocol vulnerabilities weren=E2=80=99t celebrated as "fair gam=
e" but
> rather were treated as failures to be remediated. Treating quantum theft
> differently risks rewriting Bitcoin=E2=80=99s history as a free-for-all r=
ather than
> a system that seeks to protect its users.
>
> Violation of Property Rights
> Allowing a quantum adversary to take control of funds undermines the
> fundamental principle of cryptocurrency - if you keep your keys in your
> possession, only you should be able to access your money. Bitcoin is buil=
t
> on the idea that private keys secure an individual=E2=80=99s assets, and
> unauthorized access (even via advanced tech) is theft, not a legitimate
> transfer.
>
> Erosion of Trust in Bitcoin
> If quantum attackers can exploit vulnerable addresses, confidence in
> Bitcoin as a secure store of value would collapse. Users and investors re=
ly
> on cryptographic integrity, and widespread theft could drive adoption awa=
y
> from Bitcoin, destabilizing its ecosystem.
>
> This is essentially the counterpoint to claiming the burning of vulnerabl=
e
> funds is a violation of property rights. While some will certainly see it
> as such, others will find the apathy toward stopping quantum theft to be
> similarly concerning.
>
> Unfair Advantage
> Quantum attackers, likely equipped with rare and expensive technology,
> would have an unjust edge over regular users who lack access to such tool=
s.
> This creates an inequitable system where only the technologically elite c=
an
> exploit others, contradicting Bitcoin=E2=80=99s ethos of decentralized po=
wer.
>
> Bitcoin is designed to create an asymmetric advantage for DEFENDING one's
> wealth. It's supposed to be impractically expensive for attackers to crac=
k
> the entropy and cryptography protecting one's coins. But now we find
> ourselves discussing a situation where this asymmetric advantage is
> compromised in favor of a specific class of attackers.
>
> Economic Disruption
> Large-scale theft from vulnerable addresses could crash Bitcoin=E2=80=99s=
 price as
> quantum recovered funds are dumped on exchanges. This would harm all
> holders, not just those directly targeted, leading to broader financial
> chaos in the markets.
>
> Moral Responsibility
> Permitting theft via quantum computing sets a precedent that technologica=
l
> superiority justifies unethical behavior. This is essentially taking a
> "code is law" stance in which we refuse to admit that both code and laws
> can be modified to adapt to previously unforeseen situations.
>
> Burning of coins can certainly be considered a form of theft, thus I thin=
k
> it's worth differentiating the two different thefts being discussed:
>
> 1. self-enriching & likely malicious
> 2. harm prevention & not necessarily malicious
>
> Both options lack the consent of the party whose coins are being burnt or
> transferred, thus I think the simple argument that theft is immoral becom=
es
> a wash and it's important to drill down into the details of each.
>
> Incentives Drive Security
> I can tell you from a decade of working in Bitcoin security - the average
> user is lazy and is a procrastinator. If Bitcoiners are given a "drop dea=
d
> date" after which they know vulnerable funds will be burned, this pressur=
e
> accelerates the adoption of post-quantum cryptography and strengthens
> Bitcoin long-term. Allowing vulnerable users to delay upgrading
> indefinitely will result in more laggards, leaving the network more expos=
ed
> when quantum tech becomes available.
>
> Steel Manning
> Clearly this is a complex and controversial topic, thus it's worth
> thinking through the opposing arguments.
>
> Protecting Property Rights
> Allowing quantum computers to take vulnerable bitcoin could potentially b=
e
> spun as a hard money narrative - we care so greatly about not violating
> someone's access to their coins that we allow them to be stolen!
>
> But I think the flip side to the property rights narrative is that burnin=
g
> vulnerable coins prevents said property from falling into undeserving
> hands. If the entire Bitcoin ecosystem just stands around and allows
> quantum adversaries to claim funds that rightfully belong to other users,
> is that really a "win" in the "protecting property rights" category? It
> feels more like apathy to me.
>
> As such, I think the "protecting property rights" argument is a wash.
>
> Quantum Computers Won't Attack Bitcoin
> There is a great deal of skepticism that sufficiently powerful quantum
> computers will ever exist, so we shouldn't bother preparing for a
> non-existent threat. Others have argued that even if such a computer was
> built, a quantum attacker would not go after bitcoin because they wouldn'=
t
> want to reveal their hand by doing so, and would instead attack other
> infrastructure.
>
> It's quite difficult to quantify exactly how valuable attacking other
> infrastructure would be. It also really depends upon when an entity gains
> quantum supremacy and thus if by that time most of the world's systems ha=
ve
> already been upgraded. While I think you could argue that certain entitie=
s
> gaining quantum capability might not attack Bitcoin, it would only delay
> the inevitable - eventually somebody will achieve the capability who
> decides to use it for such an attack.
>
> Quantum Attackers Would Only Steal Small Amounts
> Some have argued that even if a quantum attacker targeted bitcoin, they'd
> only go after old, likely lost P2PK outputs so as to not arouse suspicion
> and cause a market panic.
>
> I'm not so sure about that; why go after 50 BTC at a time when you could
> take 250,000 BTC with the same effort as 50 BTC? This is a classic "zero
> day exploit" game theory in which an attacker knows they have a limited
> amount of time before someone else discovers the exploit and either
> benefits from it or patches it. Take, for example, the recent ByBit attac=
k
> - the highest value crypto hack of all time. Lazarus Group had compromise=
d
> the Safe wallet front end JavaScript app and they could have simply had i=
t
> reassign ownership of everyone's Safe wallets as they were interacting wi=
th
> their wallet. But instead they chose to only specifically target ByBit's
> wallet with $1.5 billion in it because they wanted to maximize their
> extractable value. If Lazarus had started stealing from every wallet, the=
y
> would have been discovered quickly and the Safe web app would likely have
> been patched well before any billion dollar wallets executed the maliciou=
s
> code.
>
> I think the "only stealing small amounts" argument is strongest for
> Situation #2 described earlier, where a quantum attacker arrives before
> quantum safe cryptography has been deployed across the Bitcoin ecosystem.
> Because if it became clear that Bitcoin's cryptography was broken AND the=
re
> was nowhere safe for vulnerable users to migrate, the only logical option
> would be for everyone to liquidate their bitcoin as quickly as possible. =
As
> such, I don't think it applies as strongly for situations in which we hav=
e
> a migration path available.
>
> The 21 Million Coin Supply Should be in Circulation
> Some folks are arguing that it's important for the "circulating /
> spendable" supply to be as close to 21M as possible and that having a
> significant portion of the supply out of circulation is somehow undesirab=
le.
>
> While the "21M BTC" attribute is a strong memetic narrative, I don't thin=
k
> anyone has ever expected that it would all be in circulation. It has alwa=
ys
> been understood that many coins will be lost, and that's actually part of
> the game theory of owning bitcoin!
>
> And remember, the 21M number in and of itself is not a particularly
> important detail - it's not even mentioned in the whitepaper. What's
> important is that the supply is well known and not subject to change.
>
> Self-Sovereignty and Personal Responsibility
> Bitcoin=E2=80=99s design empowers individuals to control their own wealth=
, free
> from centralized intervention. This freedom comes with the burden of
> securing one's private keys. If quantum computing can break obsolete
> cryptography, the fault lies with users who didn't move their funds to
> quantum safe locking scripts. Expecting the network to shield users from
> their own negligence undermines the principle that you, and not a third
> party, are accountable for your assets.
>
> I think this is generally a fair point that "the community" doesn't owe
> you anything in terms of helping you. I think that we do, however, need t=
o
> consider the incentives and game theory in play with regard to quantum sa=
fe
> Bitcoiners vs quantum vulnerable Bitcoiners. More on that later.
>
> Code is Law
> Bitcoin operates on transparent, immutable rules embedded in its protocol=
.
> If a quantum attacker uses superior technology to derive private keys fro=
m
> public keys, they=E2=80=99re not "hacking" the system - they're simply fo=
llowing
> what's mathematically permissible within the current code. Altering the
> protocol to stop this introduces subjective human intervention, which
> clashes with the objective, deterministic nature of blockchain.
>
> While I tend to agree that code is law, one of the entire points of laws
> is that they can be amended to improve their efficacy in reducing harm.
> Leaning on this point seems more like a pro-ossification stance that it's
> better to do nothing and allow harm to occur rather than take action to
> stop an attack that was foreseen far in advance.
>
> Technological Evolution as a Feature, Not a Bug
> It's well known that cryptography tends to weaken over time and eventuall=
y
> break. Quantum computing is just the next step in this progression. Users
> who fail to adapt (e.g., by adopting quantum-resistant wallets when
> available) are akin to those who ignored technological advancements like
> multisig or hardware wallets. Allowing quantum theft incentivizes
> innovation and keeps Bitcoin=E2=80=99s ecosystem dynamic, punishing compl=
acency
> while rewarding vigilance.
>
> Market Signals Drive Security
> If quantum attackers start stealing funds, it sends a clear signal to the
> market: upgrade your security or lose everything. This pressure accelerat=
es
> the adoption of post-quantum cryptography and strengthens Bitcoin
> long-term. Coddling vulnerable users delays this necessary evolution,
> potentially leaving the network more exposed when quantum tech becomes
> widely accessible. Theft is a brutal but effective teacher.
>
> Centralized Blacklisting Power
> Burning vulnerable funds requires centralized decision-making - a soft
> fork to invalidate certain transactions. This sets a dangerous precedent
> for future interventions, eroding Bitcoin=E2=80=99s decentralization. If =
quantum
> theft is blocked, what=E2=80=99s next - reversing exchange hacks? The sys=
tem must
> remain neutral, even if it means some lose out.
>
> I think this could be a potential slippery slope if the proposal was to
> only burn specific addresses. Rather, I'd expect a neutral proposal to bu=
rn
> all funds in locking script types that are known to be quantum vulnerable=
.
> Thus, we could eliminate any subjectivity from the code.
>
> Fairness in Competition
> Quantum attackers aren't cheating; they're using publicly available
> physics and math. Anyone with the resources and foresight can build or
> access quantum tech, just as anyone could mine Bitcoin in 2009 with a CPU=
.
> Early adopters took risks and reaped rewards; quantum innovators are doin=
g
> the same. Calling it =E2=80=9Cunfair=E2=80=9D ignores that Bitcoin has ne=
ver promised
> equality of outcome - only equality of opportunity within its rules.
>
> I find this argument to be a mischaracterization because we're not talkin=
g
> about CPUs. This is more akin to talking about ASICs, except each ASIC
> costs millions if not billions of dollars. This is out of reach from all
> but the wealthiest organizations.
>
> Economic Resilience
> Bitcoin has weathered thefts before (MTGOX, Bitfinex, FTX, etc) and
> emerged stronger. The market can absorb quantum losses, with unaffected
> users continuing to hold and new entrants buying in at lower prices. Fear
> of economic collapse overestimates the impact - the network=E2=80=99s ant=
ifragility
> thrives on such challenges.
>
> This is a big grey area because we don't know when a quantum computer wil=
l
> come online and we don't know how quickly said computers would be able to
> steal bitcoin. If, for example, the first generation of sufficiently
> powerful quantum computers were stealing less volume than the current blo=
ck
> reward then of course it will have minimal economic impact. But if they'r=
e
> taking thousands of BTC per day and bringing them back into circulation,
> there will likely be a noticeable market impact as it absorbs the new
> supply.
>
> This is where the circumstances will really matter. If a quantum attacker
> appears AFTER the Bitcoin protocol has been upgraded to support quantum
> resistant cryptography then we should expect the most valuable active
> wallets will have upgraded and the juiciest target would be the 31,000 BT=
C
> in the address 12ib7dApVFvg82TXKycWBNpN8kFyiAN1dr which has been dormant
> since 2010. In general I'd expect that the amount of BTC re-entering the
> circulating supply would look somewhat similar to the mining emission
> curve: volume would start off very high as the most valuable addresses ar=
e
> drained and then it would fall off as quantum computers went down the lis=
t
> targeting addresses with less and less BTC.
>
> Why is economic impact a factor worth considering? Miners and businesses
> in general. More coins being liquidated will push down the price, which
> will negatively impact miner revenue. Similarly, I can attest from workin=
g
> in the industry for a decade, that lower prices result in less demand fro=
m
> businesses across the entire industry. As such, burning quantum vulnerabl=
e
> bitcoin is good for the entire industry.
>
> Practicality & Neutrality of Non-Intervention
> There=E2=80=99s no reliable way to distinguish =E2=80=9Ctheft=E2=80=9D fr=
om legitimate "white hat"
> key recovery. If someone loses their private key and a quantum computer
> recovers it, is that stealing or reclaiming? Policing quantum actions
> requires invasive assumptions about intent, which Bitcoin=E2=80=99s trust=
less
> design can=E2=80=99t accommodate. Letting the chips fall where they may a=
voids this
> mess.
>
> Philosophical Purity
> Bitcoin rejects bailouts. It=E2=80=99s a cold, hard system where outcomes=
 reflect
> preparation and skill, not sentimentality. If quantum computing upends th=
e
> game, that=E2=80=99s the point - Bitcoin isn=E2=80=99t meant to be safe o=
r fair in a
> nanny-state sense; it=E2=80=99s meant to be free. Users who lose funds to=
 quantum
> attacks are casualties of liberty and their own ignorance, not victims of
> injustice.
>
> Bitcoin's DAO Moment
> This situation has some similarities to The DAO hack of an Ethereum smart
> contract in 2016, which resulted in a fork to stop the attacker and retur=
n
> funds to their original owners. The game theory is similar because it's a
> situation where a threat is known but there's some period of time before
> the attacker can actually execute the theft. As such, there's time to
> mitigate the attack by changing the protocol.
>
> It also created a schism in the community around the true meaning of "cod=
e
> is law," resulting in Ethereum Classic, which decided to allow the attack=
er
> to retain control of the stolen funds.
>
> A soft fork to burn vulnerable bitcoin could certainly result in a hard
> fork if there are enough miners who reject the soft fork and continue
> including transactions.
>
> Incentives Matter
> We can wax philosophical until the cows come home, but what are the actua=
l
> incentives for existing Bitcoin holders regarding this decision?
>
> "Lost coins only make everyone else's coins worth slightly more. Think of
>> it as a donation to everyone." - Satoshi Nakamoto
>
>
> If true, the corollary is:
>
> "Quantum recovered coins only make everyone else's coins worth less. Thin=
k
>> of it as a theft from everyone." - Jameson Lopp
>
>
> Thus, assuming we get to a point where quantum resistant signatures are
> supported within the Bitcoin protocol, what's the incentive to let
> vulnerable coins remain spendable?
>
> * It's not good for the actual owners of those coins. It disincentivizes
> owners from upgrading until perhaps it's too late.
> * It's not good for the more attentive / responsible owners of coins who
> have quantum secured their stash. Allowing the circulating supply to
> balloon will assuredly reduce the purchasing power of all bitcoin holders=
.
>
> Forking Game Theory
> From a game theory point of view, I see this as incentivizing users to
> upgrade their wallets. If you disagree with the burning of vulnerable
> coins, all you have to do is move your funds to a quantum safe signature
> scheme. Point being, I don't see there being an economic majority (or eve=
n
> more than a tiny minority) of users who would fight such a soft fork. Why
> expend significant resources fighting a fork when you can just move your
> coins to a new address?
>
> Remember that blocking spending of certain classes of locking scripts is =
a
> tightening of the rules - a soft fork. As such, it can be meaningfully
> enacted and enforced by a mere majority of hashpower. If miners generally
> agree that it's in their best interest to burn vulnerable coins, are othe=
r
> users going to care enough to put in the effort to run new node software
> that resists the soft fork? Seems unlikely to me.
>
> How to Execute Burning
> In order to be as objective as possible, the goal would be to announce to
> the world that after a specific block height / timestamp, Bitcoin nodes
> will no longer accept transactions (or blocks containing such transaction=
s)
> that spend funds from any scripts other than the newly instituted quantum
> safe schemes.
>
> It could take a staggered approach to first freeze funds that are
> susceptible to long-range attacks such as those in P2PK scripts or those
> that exposed their public keys due to previously re-using addresses, but =
I
> expect the additional complexity would drive further controversy.
>
> How long should the grace period be in order to give the ecosystem time t=
o
> upgrade? I'd say a minimum of 1 year for software wallets to upgrade. We
> can only hope that hardware wallet manufacturers are able to implement po=
st
> quantum cryptography on their existing hardware with only a firmware upda=
te.
>
> Beyond that, it will take at least 6 months worth of block space for all
> users to migrate their funds, even in a best case scenario. Though if you
> exclude dust UTXOs you could probably get 95% of BTC value migrated in 1
> month. Of course this is a highly optimistic situation where everyone is
> completely focused on migrations - in reality it will take far longer.
>
> Regardless, I'd think that in order to reasonably uphold Bitcoin's
> conservatism it would be preferable to allow a 4 year migration window. I=
n
> the meantime, mining pools could coordinate emergency soft forking logic
> such that if quantum attackers materialized, they could accelerate the
> countdown to the quantum vulnerable funds burn.
>
> Random Tangential Benefits
> On the plus side, burning all quantum vulnerable bitcoin would allow us t=
o
> prune all of those UTXOs out of the UTXO set, which would also clean up a
> lot of dust. Dust UTXOs are a bit of an annoyance and there has even been=
 a
> recent proposal for how to incentivize cleaning them up.
>
> We should also expect that incentivizing migration of the entire UTXO set
> will create substantial demand for block space that will sustain a fee
> market for a fairly lengthy amount of time.
>
> In Summary
> While the moral quandary of violating any of Bitcoin's inviolable
> properties can make this a very complex issue to discuss, the game theory
> and incentives between burning vulnerable coins versus allowing them to b=
e
> claimed by entities with quantum supremacy appears to be a much simpler
> issue.
>
> I, for one, am not interested in rewarding quantum capable entities by
> inflating the circulating money supply just because some people lost thei=
r
> keys long ago and some laggards are not upgrading their bitcoin wallet's
> security.
>
> We can hope that this scenario never comes to pass, but hope is not a
> strategy.
>
> I welcome your feedback upon any of the above points, and contribution of
> any arguments I failed to consider.
>
> --
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<div dir=3D"ltr">This makes a lot of sense.=C2=A0 One would think that prio=
r to an attack on bitcoin other coins would be attacked first, e.g. Ethereu=
m given the way I understand that public keys are exposed vs bitcoin, so th=
ere could be some warning from softer, vulnerable and valuable targets to a=
ttack such as alt coins, governments, and financial institutions. =C2=A0<br=
><br>However, none of this changes the points you made and the importance o=
f looking at the issue sooner versus later given the long lead time that wi=
ll be necessary since there could be little warning.=C2=A0 I have seen esti=
mates in the 2030-2035 range for a potential attack and the US Federal gove=
rnment tells agencies they must transition by 2035 to a quantum safe scheme=
 further emphasizing the potential urgency.<div><br>Of course, some argue i=
t could take &quot;decades&quot; or even longer=E2=80=94if it ever happens =
at all=E2=80=94so there is significant uncertainty about when a successful =
attack might occur. To me, this is a &quot;prepare for the worst and hope f=
or the best&quot; scenario. As you noted, whether coins are &quot;burned&qu=
ot; or &quot;stolen,&quot; the outcome is the same for their owners: they l=
ose control of their assets. Logically, they might even prefer for their co=
ins to be burned rather than stolen, as it would prevent dilution of any re=
maining holdings and help mitigate systemic damage to the ecosystem.<br><br=
>Thanks :-)<br><div><div dir=3D"ltr"><div><div><br></div><div><br></div></d=
iv></div><br><div class=3D"gmail_quote gmail_quote_container"><div dir=3D"l=
tr" class=3D"gmail_attr">On Sun, Mar 16, 2025 at 11:22=E2=80=AFAM Jameson L=
opp &lt;<a href=3D"mailto:jameson.lopp@gmail.com">jameson.lopp@gmail.com</a=
>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px=
 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-co=
lor:rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">The quantum computi=
ng debate is heating up. There are many controversial aspects to this debat=
e, including whether or not quantum computers will ever actually become a p=
ractical threat.<div><br>I won&#39;t tread into the unanswerable question o=
f how worried we should be about quantum computers. I think it&#39;s far fr=
om a crisis, but given the difficulty in changing Bitcoin it&#39;s worth st=
arting to seriously discuss. Today I wish to focus on a philosophical quand=
ary related to one of the decisions that would need to be made if and when =
we implement a quantum safe signature scheme.<br><br><font size=3D"6">Sever=
al Scenarios<br></font>Because this essay will reference game theory a fair=
 amount, and there are many variables at play that could change the nature =
of the game, I think it&#39;s important to clarify the possible scenarios u=
p front.<br><br>1. Quantum computing never materializes, never becomes a th=
reat, and thus everything discussed in this essay is moot.<br>2. A quantum =
computing threat materializes suddenly and Bitcoin does not have quantum sa=
fe signatures as part of the protocol. In this scenario it would likely mak=
e the points below moot because Bitcoin would be fundamentally broken and i=
t would take far too long to upgrade the protocol, wallet software, and mig=
rate user funds in order to restore confidence in the network.<br>3. Quantu=
m computing advances slowly enough that we come to consensus about how to u=
pgrade Bitcoin and post quantum security has been minimally adopted by the =
time an attacker appears.<br>4. Quantum computing advances slowly enough th=
at we come to consensus about how to upgrade Bitcoin and post quantum secur=
ity has been highly adopted by the time an attacker appears.<br><br>For the=
 purposes of this post, I&#39;m envisioning being in situation 3 or 4.<br><=
br><font size=3D"6">To Freeze or not to Freeze?<br></font>I&#39;ve started =
seeing more people weighing in on what is likely the most contentious aspec=
t of how a quantum resistance upgrade should be handled in terms of migrati=
ng user funds. Should quantum vulnerable funds be left open to be swept by =
anyone with a sufficiently powerful quantum computer OR should they be perm=
anently locked?<br><br><blockquote class=3D"gmail_quote" style=3D"margin:0p=
x 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-c=
olor:rgb(204,204,204);padding-left:1ex">&quot;I don&#39;t see why old coins=
 should be confiscated. The better option is to let those with quantum comp=
uters free up old coins. While this might have an inflationary impact on bi=
tcoin&#39;s price, to use a turn of phrase, the inflation is transitory. Th=
ose with low time preference should support returning lost coins to circula=
tion.&quot;=C2=A0</blockquote><blockquote class=3D"gmail_quote" style=3D"ma=
rgin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border=
-left-color:rgb(204,204,204);padding-left:1ex">- Hunter Beast</blockquote><=
div><br></div>On the other hand:</div><div><br><blockquote class=3D"gmail_q=
uote" style=3D"margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-s=
tyle:solid;border-left-color:rgb(204,204,204);padding-left:1ex">&quot;Of co=
urse they have to be confiscated. If and when (and that&#39;s a big if) the=
 existence of a cryptography-breaking QC becomes a credible threat, the Bit=
coin ecosystem has no other option than softforking out the ability to spen=
d from signature schemes (including ECDSA and BIP340) that are vulnerable t=
o QCs. The alternative is that millions of BTC become vulnerable to theft; =
I cannot see how the currency can maintain any value at all in such a setti=
ng. And this affects everyone; even those which diligently moved their coin=
s to PQC-protected schemes.&quot;<br>- Pieter Wuille</blockquote><br>I don&=
#39;t think &quot;confiscation&quot; is the most precise term to use, as th=
e funds are not being seized and reassigned. Rather, what we&#39;re really =
discussing would be better described as &quot;burning&quot; - placing the f=
unds <b>out of reach of everyone</b>.<br><br>Not freezing user funds is one=
 of Bitcoin&#39;s inviolable properties. However, if quantum computing beco=
mes a threat to Bitcoin&#39;s elliptic curve cryptography, <b>an inviolable=
 property of Bitcoin will be violated one way or another</b>.<br><br><font =
size=3D"6">Fundamental Properties at Risk<br></font>5 years ago I attempted=
 to comprehensively categorize all of Bitcoin&#39;s fundamental properties =
that give it value. <a href=3D"https://nakamoto.com/what-are-the-key-proper=
ties-of-bitcoin/" target=3D"_blank">https://nakamoto.com/what-are-the-key-p=
roperties-of-bitcoin/<br></a><br>The particular properties in play with reg=
ard to this issue seem to be:<br><br><b>Censorship Resistance</b> - No one =
should have the power to prevent others from using their bitcoin or interac=
ting with the network.<br><br><b>Forward Compatibility</b> - changing the r=
ules such that certain valid transactions become invalid could undermine co=
nfidence in the protocol.<br><br><b>Conservatism</b> - Users should not be =
expected to be highly responsive to system issues.<br><br>As a result of th=
e above principles, we have developed a strong meme (kudos to Andreas Anton=
opoulos) that goes as follows:<br><br><blockquote class=3D"gmail_quote" sty=
le=3D"margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:soli=
d;border-left-color:rgb(204,204,204);padding-left:1ex">Not your keys, not y=
our coins.</blockquote><br>I posit that the corollary to this principle is:=
<br><br><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex=
;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,20=
4,204);padding-left:1ex">Your keys, only your coins.</blockquote><br>A quan=
tum capable entity breaks the corollary of this foundational principle. We =
secure our bitcoin with the mathematical probabilities related to extremely=
 large random numbers. Your funds are only secure because truly random larg=
e numbers should not be guessable or discoverable by anyone else in the wor=
ld.<br><br>This is the principle behind the motto <i>vires in numeris</i> -=
 strength in numbers. In a world with quantum enabled adversaries, this pri=
nciple is null and void for many types of cryptography, including the ellip=
tic curve digital signatures used in Bitcoin.<br><br><font size=3D"6">Who i=
s at Risk?<br></font>There has long been a narrative that Satoshi&#39;s coi=
ns and others from the Satoshi era of P2PK locking scripts that exposed the=
 public key directly on the blockchain will be those that get scooped up by=
 a quantum &quot;miner.&quot; But unfortunately it&#39;s not that simple. I=
f I had a powerful quantum computer, which coins would I target? I&#39;d go=
 to the Bitcoin rich list and find the wallets that have exposed their publ=
ic keys due to re-using addresses that have previously been spent from. You=
 can easily find them at <a href=3D"https://bitinfocharts.com/top-100-riche=
st-bitcoin-addresses.html" target=3D"_blank">https://bitinfocharts.com/top-=
100-richest-bitcoin-addresses.html</a><br><br>Note that a few of these wall=
ets, like Bitfinex / Kraken / Tether, would be slightly harder to crack bec=
ause they are multisig wallets. So a quantum attacker would need to reverse=
 engineer 2 keys for Kraken or 3 for Bitfinex / Tether in order to spend fu=
nds. But many are single signature.<br><br>Point being, it&#39;s not only t=
he really old lost BTC that are at risk to a quantum enabled adversary, at =
least at time of writing. If we add a quantum safe signature scheme, we sho=
uld expect those wallets to be some of the first to upgrade given their inc=
entives.<br><br><font size=3D"6">The Ethical Dilemma: Quantifying Harm<br><=
/font>Which decision results in the most harm?<br><br>By making quantum vul=
nerable funds unspendable we potentially harm some Bitcoin users who were n=
ot paying attention and neglected to migrate their funds to a quantum safe =
locking script. This violates the &quot;conservativism&quot; principle stat=
ed earlier. On the flip side, we prevent those funds plus far more lost fun=
ds from falling into the hands of the few privileged folks who gain early a=
ccess to quantum computers.<br><br>By leaving quantum vulnerable funds avai=
lable to spend, the same set of users who would otherwise have funds frozen=
 are likely to see them stolen. And many early adopters who lost their keys=
 will eventually see their unreachable funds scooped up by a quantum enable=
d adversary.<br><br>Imagine, for example, being James Howells, who accident=
ally threw away a hard drive with 8,000 BTC on it, currently worth over $60=
0M USD. He has spent a decade trying to retrieve it from the landfill where=
 he knows it&#39;s buried, but can&#39;t get permission to excavate. I susp=
ect that, given the choice, he&#39;d prefer those funds be permanently froz=
en rather than fall into someone else&#39;s possession - I know I would.<br=
><br>Allowing a quantum computer to access lost funds doesn&#39;t make thos=
e users any worse off than they were before, however it <i>would</i> have a=
 negative impact upon everyone who is currently holding bitcoin.<br><br>It&=
#39;s prudent to expect significant economic disruption if large amounts of=
 coins fall into new hands. Since a quantum computer is going to have a mas=
sive up front cost, expect those behind it to desire to recoup their invest=
ment. We also know from experience that when someone suddenly finds themsel=
ves in possession of 9+ figures worth of highly liquid assets, they tend to=
 diversify into other things by selling.<br><br>Allowing quantum recovery o=
f bitcoin is <i>tantamount to wealth redistribution</i>. What we&#39;d be a=
llowing is for bitcoin to be redistributed from those who are ignorant of q=
uantum computers to those who have won the technological race to acquire qu=
antum computers. It&#39;s hard to see a bright side to that scenario.<br><b=
r><font size=3D"6">Is Quantum Recovery Good for Anyone?</font><br><br>Does =
quantum recovery HELP anyone? I&#39;ve yet to come across an argument that =
it&#39;s a net positive in any way. It certainly doesn&#39;t add any securi=
ty to the network. If anything, it greatly decreases the security of the ne=
twork by allowing funds to be claimed by those who did not earn them.<br><b=
r>But wait, you may be thinking, wouldn&#39;t quantum &quot;miners&quot; ha=
ve earned their coins by all the work and resources invested in building a =
quantum computer? I suppose, in the same sense that a burglar earns their s=
poils by the resources they invest into surveilling targets and learning th=
e skills needed to break into buildings. What I say &quot;earned&quot; I me=
an through productive mutual trade.<br><br>For example:<br><br>* Investors =
earn BTC by trading for other currencies.<br>* Merchants earn BTC by tradin=
g for goods and services.<br>* Miners earn BTC by trading thermodynamic sec=
urity.<br>* Quantum miners don&#39;t trade anything, they are vampires feed=
ing upon the system.<br><br>There&#39;s no reason to believe that allowing =
quantum adversaries to recover vulnerable bitcoin will be of benefit to any=
one other than the select few organizations that win the technological arms=
 race to build the first such computers. Probably nation states and/or the =
top few largest tech companies.<br><br>One could certainly hope that an org=
anization with quantum supremacy is benevolent and acts in a &quot;white ha=
t&quot; manner to return lost coins to their owners, but that&#39;s incredi=
bly optimistic and foolish to rely upon. Such a situation creates an insurm=
ountable ethical dilemma of only recovering lost bitcoin rather than curren=
tly owned bitcoin. There&#39;s no way to precisely differentiate between th=
e two; anyone can claim to have lost their bitcoin but if they have lost th=
eir keys then proving they ever had the keys becomes rather difficult. I im=
agine that any such white hat recovery efforts would have to rely upon atte=
stations from trusted third parties like exchanges.<br><br>Even if the firs=
t actor with quantum supremacy is benevolent, we must assume the technology=
 could fall into adversarial hands and thus think adversarially about the p=
otential worst case outcomes. Imagine, for example, that North Korea contin=
ues scooping up billions of dollars from hacking crypto exchanges and decid=
es to invest some of those proceeds into building a quantum computer for th=
e biggest payday ever...<br><br><font size=3D"6">Downsides to Allowing Quan=
tum Recovery</font><br>Let&#39;s think through an exhaustive list of pros a=
nd cons for allowing or preventing the seizure of funds by a quantum advers=
ary.<br><br><font size=3D"4">Historical Precedent</font><br>Previous protoc=
ol vulnerabilities weren=E2=80=99t celebrated as &quot;fair game&quot; but =
rather were treated as failures to be remediated. Treating quantum theft di=
fferently risks rewriting Bitcoin=E2=80=99s history as a free-for-all rathe=
r than a system that seeks to protect its users.<br><br><font size=3D"4">Vi=
olation of Property Rights</font><br>Allowing a quantum adversary to take c=
ontrol of funds undermines the fundamental principle of cryptocurrency - if=
 you keep your keys in your possession, only you should be able to access y=
our money. Bitcoin is built on the idea that private keys secure an individ=
ual=E2=80=99s assets, and unauthorized access (even via advanced tech) is t=
heft, not a legitimate transfer.<br><br><font size=3D"4">Erosion of Trust i=
n Bitcoin</font><br>If quantum attackers can exploit vulnerable addresses, =
confidence in Bitcoin as a secure store of value would collapse. Users and =
investors rely on cryptographic integrity, and widespread theft could drive=
 adoption away from Bitcoin, destabilizing its ecosystem.<br><br>This is es=
sentially the counterpoint to claiming the burning of vulnerable funds is a=
 violation of property rights. While some will certainly see it as such, ot=
hers will find the apathy toward stopping quantum theft to be similarly con=
cerning.<br><br><font size=3D"4">Unfair Advantage</font><br>Quantum attacke=
rs, likely equipped with rare and expensive technology, would have an unjus=
t edge over regular users who lack access to such tools. This creates an in=
equitable system where only the technologically elite can exploit others, c=
ontradicting Bitcoin=E2=80=99s ethos of decentralized power.<br><br>Bitcoin=
 is designed to create an asymmetric advantage for DEFENDING one&#39;s weal=
th. It&#39;s supposed to be impractically expensive for attackers to crack =
the entropy and cryptography protecting one&#39;s coins. But now we find ou=
rselves discussing a situation where this asymmetric advantage is compromis=
ed in favor of a specific class of attackers.<br><br><font size=3D"4">Econo=
mic Disruption</font><br>Large-scale theft from vulnerable addresses could =
crash Bitcoin=E2=80=99s price as quantum recovered funds are dumped on exch=
anges. This would harm all holders, not just those directly targeted, leadi=
ng to broader financial chaos in the markets.<br><br><font size=3D"4">Moral=
 Responsibility</font><br>Permitting theft via quantum computing sets a pre=
cedent that technological superiority justifies unethical behavior. This is=
 essentially taking a &quot;code is law&quot; stance in which we refuse to =
admit that both code and laws can be modified to adapt to previously unfore=
seen situations.<br><br>Burning of coins can certainly be considered a form=
 of theft, thus I think it&#39;s worth differentiating the two different th=
efts being discussed:<br><br>1. self-enriching &amp; likely malicious<br>2.=
 harm prevention &amp; not necessarily malicious<br><br>Both options lack t=
he consent of the party whose coins are being burnt or transferred, thus I =
think the simple argument that theft is immoral becomes a wash and it&#39;s=
 important to drill down into the details of each.<br><br><font size=3D"4">=
Incentives Drive Security</font><br>I can tell you from a decade of working=
 in Bitcoin security - the average user is lazy and is a procrastinator. If=
 Bitcoiners are given a &quot;drop dead date&quot; after which they know vu=
lnerable funds will be burned, this pressure accelerates the adoption of po=
st-quantum cryptography and strengthens Bitcoin long-term. Allowing vulnera=
ble users to delay upgrading indefinitely will result in more laggards, lea=
ving the network more exposed when quantum tech becomes available.<br><br><=
font size=3D"6">Steel Manning<br></font>Clearly this is a complex and contr=
oversial topic, thus it&#39;s worth thinking through the opposing arguments=
.<br><br><font size=3D"4">Protecting Property Rights</font><br>Allowing qua=
ntum computers to take vulnerable bitcoin could potentially be spun as a ha=
rd money narrative - we care so greatly about not violating someone&#39;s a=
ccess to their coins that we allow them to be stolen!<br><br>But I think th=
e flip side to the property rights narrative is that burning vulnerable coi=
ns prevents said property from falling into undeserving hands. If the entir=
e Bitcoin ecosystem just stands around and allows quantum adversaries to cl=
aim funds that rightfully belong to other users, is that really a &quot;win=
&quot; in the &quot;protecting property rights&quot; category? It feels mor=
e like apathy to me.<br><br>As such, I think the &quot;protecting property =
rights&quot; argument is a wash.<br><br><font size=3D"4">Quantum Computers =
Won&#39;t Attack Bitcoin</font><br>There is a great deal of skepticism that=
 sufficiently powerful quantum computers will ever exist, so we shouldn&#39=
;t bother preparing for a non-existent threat. Others have argued that even=
 if such a computer was built, a quantum attacker would not go after bitcoi=
n because they wouldn&#39;t want to reveal their hand by doing so, and woul=
d instead attack other infrastructure.<br><br>It&#39;s quite difficult to q=
uantify exactly how valuable attacking other infrastructure would be. It al=
so really depends upon when an entity gains quantum supremacy and thus if b=
y that time most of the world&#39;s systems have already been upgraded. Whi=
le I think you could argue that certain entities gaining quantum capability=
 might not attack Bitcoin, it would only delay the inevitable - eventually =
somebody will achieve the capability who decides to use it for such an atta=
ck.<br><br><font size=3D"4">Quantum Attackers Would Only Steal Small Amount=
s</font><br>Some have argued that even if a quantum attacker targeted bitco=
in, they&#39;d only go after old, likely lost P2PK outputs so as to not aro=
use suspicion and cause a market panic.<br><br>I&#39;m not so sure about th=
at; why go after 50 BTC at a time when you could take 250,000 BTC with the =
same effort as 50 BTC? This is a classic &quot;zero day exploit&quot; game =
theory in which an attacker knows they have a limited amount of time before=
 someone else discovers the exploit and either benefits from it or patches =
it. Take, for example, the recent ByBit attack - the highest value crypto h=
ack of all time. Lazarus Group had compromised the Safe wallet front end Ja=
vaScript app and they could have simply had it reassign ownership of everyo=
ne&#39;s Safe wallets as they were interacting with their wallet. But inste=
ad they chose to only specifically target ByBit&#39;s wallet with $1.5 bill=
ion in it because they wanted to maximize their extractable value. If Lazar=
us had started stealing from every wallet, they would have been discovered =
quickly and the Safe web app would likely have been patched well before any=
 billion dollar wallets executed the malicious code.<br><br>I think the &qu=
ot;only stealing small amounts&quot; argument is strongest for Situation #2=
 described earlier, where a quantum attacker arrives before quantum safe cr=
yptography has been deployed across the Bitcoin ecosystem. Because if it be=
came clear that Bitcoin&#39;s cryptography was broken AND there was nowhere=
 safe for vulnerable users to migrate, the only logical option would be for=
 everyone to liquidate their bitcoin as quickly as possible. As such, I don=
&#39;t think it applies as strongly for situations in which we have a migra=
tion path available.<br><br><font size=3D"4">The 21 Million Coin Supply Sho=
uld be in Circulation</font><br>Some folks are arguing that it&#39;s import=
ant for the &quot;circulating / spendable&quot; supply to be as close to 21=
M as possible and that having a significant portion of the supply out of ci=
rculation is somehow undesirable.<br><br>While the &quot;21M BTC&quot; attr=
ibute is a strong memetic narrative, I don&#39;t think anyone has ever expe=
cted that it would all be in circulation. It has always been understood tha=
t many coins will be lost, and that&#39;s actually part of the game theory =
of owning bitcoin!<br><br>And remember, the 21M number in and of itself is =
not a particularly important detail - it&#39;s not even mentioned in the wh=
itepaper. What&#39;s important is that the supply is well known and not sub=
ject to change.<br><br><font size=3D"4">Self-Sovereignty and Personal Respo=
nsibility</font><br>Bitcoin=E2=80=99s design empowers individuals to contro=
l their own wealth, free from centralized intervention. This freedom comes =
with the burden of securing one&#39;s private keys. If quantum computing ca=
n break obsolete cryptography, the fault lies with users who didn&#39;t mov=
e their funds to quantum safe locking scripts. Expecting the network to shi=
eld users from their own negligence undermines the principle that you, and =
not a third party, are accountable for your assets.<br><br>I think this is =
generally a fair point that &quot;the community&quot; doesn&#39;t owe you a=
nything in terms of helping you. I think that we do, however, need to consi=
der the incentives and game theory in play with regard to quantum safe Bitc=
oiners vs quantum vulnerable Bitcoiners. More on that later.<br><br><font s=
ize=3D"4">Code is Law</font><br>Bitcoin operates on transparent, immutable =
rules embedded in its protocol. If a quantum attacker uses superior technol=
ogy to derive private keys from public keys, they=E2=80=99re not &quot;hack=
ing&quot; the system - they&#39;re simply following what&#39;s mathematical=
ly permissible within the current code. Altering the protocol to stop this =
introduces subjective human intervention, which clashes with the objective,=
 deterministic nature of blockchain.<br><br>While I tend to agree that code=
 is law, one of the entire points of laws is that they can be amended to im=
prove their efficacy in reducing harm. Leaning on this point seems more lik=
e a pro-ossification stance that it&#39;s better to do nothing and allow ha=
rm to occur rather than take action to stop an attack that was foreseen far=
 in advance.<br><br><font size=3D"4">Technological Evolution as a Feature, =
Not a Bug</font><br>It&#39;s well known that cryptography tends to weaken o=
ver time and eventually break. Quantum computing is just the next step in t=
his progression. Users who fail to adapt (e.g., by adopting quantum-resista=
nt wallets when available) are akin to those who ignored technological adva=
ncements like multisig or hardware wallets. Allowing quantum theft incentiv=
izes innovation and keeps Bitcoin=E2=80=99s ecosystem dynamic, punishing co=
mplacency while rewarding vigilance.<br><br><font size=3D"4">Market Signals=
 Drive Security</font><br>If quantum attackers start stealing funds, it sen=
ds a clear signal to the market: upgrade your security or lose everything. =
This pressure accelerates the adoption of post-quantum cryptography and str=
engthens Bitcoin long-term. Coddling vulnerable users delays this necessary=
 evolution, potentially leaving the network more exposed when quantum tech =
becomes widely accessible. Theft is a brutal but effective teacher.<br><br>=
<font size=3D"4">Centralized Blacklisting Power</font><br>Burning vulnerabl=
e funds requires centralized decision-making - a soft fork to invalidate ce=
rtain transactions. This sets a dangerous precedent for future intervention=
s, eroding Bitcoin=E2=80=99s decentralization. If quantum theft is blocked,=
 what=E2=80=99s next - reversing exchange hacks? The system must remain neu=
tral, even if it means some lose out.<br><br>I think this could be a potent=
ial slippery slope if the proposal was to only burn specific addresses. Rat=
her, I&#39;d expect a neutral proposal to burn all funds in locking script =
types that are known to be quantum vulnerable. Thus, we could eliminate any=
 subjectivity from the code.<br><br><font size=3D"4">Fairness in Competitio=
n</font><br>Quantum attackers aren&#39;t cheating; they&#39;re using public=
ly available physics and math. Anyone with the resources and foresight can =
build or access quantum tech, just as anyone could mine Bitcoin in 2009 wit=
h a CPU. Early adopters took risks and reaped rewards; quantum innovators a=
re doing the same. Calling it =E2=80=9Cunfair=E2=80=9D ignores that Bitcoin=
 has never promised equality of outcome - only equality of opportunity with=
in its rules.<br><br>I find this argument to be a mischaracterization becau=
se we&#39;re not talking about CPUs. This is more akin to talking about ASI=
Cs, except each ASIC costs millions if not billions of dollars. This is out=
 of reach from all but the wealthiest organizations.<br><br><font size=3D"4=
">Economic Resilience</font><br>Bitcoin has weathered thefts before (MTGOX,=
 Bitfinex, FTX, etc) and emerged stronger. The market can absorb quantum lo=
sses, with unaffected users continuing to hold and new entrants buying in a=
t lower prices. Fear of economic collapse overestimates the impact - the ne=
twork=E2=80=99s antifragility thrives on such challenges.<br><br>This is a =
big grey area because we don&#39;t know when a quantum computer will come o=
nline and we don&#39;t know how quickly said computers would be able to ste=
al bitcoin. If, for example, the first generation of sufficiently powerful =
quantum computers were stealing less volume than the current block reward t=
hen of course it will have minimal economic impact. But if they&#39;re taki=
ng thousands of BTC per day and bringing them back into circulation, there =
will likely be a noticeable market impact as it absorbs the new supply.<br>=
<br>This is where the circumstances will really matter. If a quantum attack=
er appears AFTER the Bitcoin protocol has been upgraded to support quantum =
resistant cryptography then we should expect the most valuable active walle=
ts will have upgraded and the juiciest target would be the 31,000 BTC in th=
e address 12ib7dApVFvg82TXKycWBNpN8kFyiAN1dr which has been dormant since 2=
010. In general I&#39;d expect that the amount of BTC re-entering the circu=
lating supply would look somewhat similar to the mining emission curve: vol=
ume would start off very high as the most valuable addresses are drained an=
d then it would fall off as quantum computers went down the list targeting =
addresses with less and less BTC.<br><br>Why is economic impact a factor wo=
rth considering? Miners and businesses in general. More coins being liquida=
ted will push down the price, which will negatively impact miner revenue. S=
imilarly, I can attest from working in the industry for a decade, that lowe=
r prices result in less demand from businesses across the entire industry. =
As such, burning quantum vulnerable bitcoin is good for the entire industry=
.<br><br><font size=3D"4">Practicality &amp; Neutrality of Non-Intervention=
</font><br>There=E2=80=99s no reliable way to distinguish =E2=80=9Ctheft=E2=
=80=9D from legitimate &quot;white hat&quot; key recovery. If someone loses=
 their private key and a quantum computer recovers it, is that stealing or =
reclaiming? Policing quantum actions requires invasive assumptions about in=
tent, which Bitcoin=E2=80=99s trustless design can=E2=80=99t accommodate. L=
etting the chips fall where they may avoids this mess.<br><br><font size=3D=
"4">Philosophical Purity</font><br>Bitcoin rejects bailouts. It=E2=80=99s a=
 cold, hard system where outcomes reflect preparation and skill, not sentim=
entality. If quantum computing upends the game, that=E2=80=99s the point - =
Bitcoin isn=E2=80=99t meant to be safe or fair in a nanny-state sense; it=
=E2=80=99s meant to be free. Users who lose funds to quantum attacks are ca=
sualties of liberty and their own ignorance, not victims of injustice.<br><=
br><font size=3D"6">Bitcoin&#39;s DAO Moment</font><br>This situation has s=
ome similarities to The DAO hack of an Ethereum smart contract in 2016, whi=
ch resulted in a fork to stop the attacker and return funds to their origin=
al owners. The game theory is similar because it&#39;s a situation where a =
threat is known but there&#39;s some period of time before the attacker can=
 actually execute the theft. As such, there&#39;s time to mitigate the atta=
ck by changing the protocol.<br><br>It also created a schism in the communi=
ty around the true meaning of &quot;code is law,&quot; resulting in Ethereu=
m Classic, which decided to allow the attacker to retain control of the sto=
len funds.<br><br>A soft fork to burn vulnerable bitcoin could certainly re=
sult in a hard fork if there are enough miners who reject the soft fork and=
 continue including transactions.<br><br><font size=3D"6">Incentives Matter=
</font><br>We can wax philosophical until the cows come home, but what are =
the actual incentives for existing Bitcoin holders regarding this decision?=
<br><br><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex=
;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,20=
4,204);padding-left:1ex">&quot;Lost coins only make everyone else&#39;s coi=
ns worth slightly more. Think of it as a donation to everyone.&quot; - Sato=
shi Nakamoto</blockquote><br>If true, the corollary is:<br><br><blockquote =
class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left-width:1=
px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:=
1ex">&quot;Quantum recovered coins only make everyone else&#39;s coins wort=
h less. Think of it as a theft from everyone.&quot; - Jameson Lopp</blockqu=
ote><br>Thus, assuming we get to a point where quantum resistant signatures=
 are supported within the Bitcoin protocol, what&#39;s the incentive to let=
 vulnerable coins remain spendable?<br><br>* It&#39;s not good for the actu=
al owners of those coins. It disincentivizes owners from upgrading until pe=
rhaps it&#39;s too late.<br>* It&#39;s not good for the more attentive / re=
sponsible owners of coins who have quantum secured their stash. Allowing th=
e circulating supply to balloon will assuredly reduce the purchasing power =
of all bitcoin holders.<br><br><font size=3D"6">Forking Game Theory</font><=
br>From a game theory point of view, I see this as incentivizing users to u=
pgrade their wallets. If you disagree with the burning of vulnerable coins,=
 all you have to do is move your funds to a quantum safe signature scheme. =
Point being, I don&#39;t see there being an economic majority (or even more=
 than a tiny minority) of users who would fight such a soft fork. Why expen=
d significant resources fighting a fork when you can just move your coins t=
o a new address?<br><br>Remember that blocking spending of certain classes =
of locking scripts is a tightening of the rules - a soft fork. As such, it =
can be meaningfully enacted and enforced by a mere majority of hashpower. I=
f miners generally agree that it&#39;s in their best interest to burn vulne=
rable coins, are other users going to care enough to put in the effort to r=
un new node software that resists the soft fork? Seems unlikely to me.<br><=
br><font size=3D"6">How to Execute Burning</font><br>In order to be as obje=
ctive as possible, the goal would be to announce to the world that after a =
specific block height / timestamp, Bitcoin nodes will no longer accept tran=
sactions (or blocks containing such transactions) that spend funds from any=
 scripts other than the newly instituted quantum safe schemes.<br><br>It co=
uld take a staggered approach to first freeze funds that are susceptible to=
 long-range attacks such as those in P2PK scripts or those that exposed the=
ir public keys due to previously re-using addresses, but I expect the addit=
ional complexity would drive further controversy.<br><br>How long should th=
e grace period be in order to give the ecosystem time to upgrade? I&#39;d s=
ay a minimum of 1 year for software wallets to upgrade. We can only hope th=
at hardware wallet manufacturers are able to implement post quantum cryptog=
raphy on their existing hardware with only a firmware update.<br><br>Beyond=
 that, it will take at least 6 months worth of block space for all users to=
 migrate their funds, even in a best case scenario. Though if you exclude d=
ust UTXOs you could probably get 95% of BTC value migrated in 1 month. Of c=
ourse this is a highly optimistic situation where everyone is completely fo=
cused on migrations - in reality it will take far longer.<br><br>Regardless=
, I&#39;d think that in order to reasonably uphold Bitcoin&#39;s conservati=
sm it would be preferable to allow a 4 year migration window. In the meanti=
me, mining pools could coordinate emergency soft forking logic such that if=
 quantum attackers materialized, they could accelerate the countdown to the=
 quantum vulnerable funds burn.<br><br><font size=3D"6">Random Tangential B=
enefits</font><br>On the plus side, burning all quantum vulnerable bitcoin =
would allow us to prune all of those UTXOs out of the UTXO set, which would=
 also clean up a lot of dust. Dust UTXOs are a bit of an annoyance and ther=
e has even been a recent proposal for how to incentivize cleaning them up.<=
br><br>We should also expect that incentivizing migration of the entire UTX=
O set will create substantial demand for block space that will sustain a fe=
e market for a fairly lengthy amount of time.<br><br><font size=3D"6">In Su=
mmary</font><br>While the moral quandary of violating any of Bitcoin&#39;s =
inviolable properties can make this a very complex issue to discuss, the ga=
me theory and incentives between burning vulnerable coins versus allowing t=
hem to be claimed by entities with quantum supremacy appears to be a much s=
impler issue.<br><br>I, for one, am not interested in rewarding quantum cap=
able entities by inflating the circulating money supply just because some p=
eople lost their keys long ago and some laggards are not upgrading their bi=
tcoin wallet&#39;s security.<br><br>We can hope that this scenario never co=
mes to pass, but hope is not a strategy.<br><br>I welcome your feedback upo=
n any of the above points, and contribution of any arguments I failed to co=
nsider.</div></div>

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