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Date: Tue, 15 Jul 2025 07:13:38 -0700 (PDT)
From: Boris Nagaev <bnagaev@gmail.com>
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
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Subject: Re: [bitcoindev] A Post Quantum Migration Proposal
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Hi Conduition, hi Jameson, hi all!

What if all vulnerable coins are temporarily locked during phase B, with a=
=20
clearly defined future block height X (e.g., in 5-10 years) at which point=
=20
these coins become EC-spendable again? This would give us time to develop=
=20
recovery mechanisms for phase C. It also wouldn't require a hard fork,=20
since the unlocking height X would already be part of the consensus rules=
=20
introduced in phase B. In this way, we avoid a hard fork altogether.=20
Instead of permanent freezing, a forced timelock would be applied to=20
vulnerable outputs.

Beyond merely avoiding a hard fork, this approach offers additional=20
benefits. It improves the situation for owners of vulnerable coins who=20
missed the initial deadline, since a timelock is preferable to permanent=20
freezing. To be clear, I am not advocating for locking the coins -- even=20
temporarily. However, if a choice must be made, temporary locking is=20
clearly preferable to permanent freezing. Developers working on recovery=20
mechanisms would have a clear timeline and incentive to deliver phase C as=
=20
a subsequent soft fork. At the same time, the community gains valuable time=
=20
for data-driven decision-making -- allowing us to adapt based on how events=
=20
unfold, including whether legitimate claims are made on locked coins, and=
=20
based on future developments in quantum computing.

This assumes that phases A and B are deployed before a real quantum threat=
=20
materializes. If, in the meantime, fundamental research concludes that=20
quantum computing will not break EC for the next 100 years, we can simply=
=20
do nothing -- and the coins will unlock automatically at height X. On the=
=20
other hand, if quantum computing advances significantly, we can respond=20
based on the availability and quality of recovery schemes: either deploy a=
=20
recovery soft fork at block X, or apply another soft fork to postpone=20
unlocking by another 5-10 years.

Best,
Boris

On Tuesday, July 15, 2025 at 8:36:33=E2=80=AFAM UTC-3 conduition wrote:

Hi Jameson,

I like your proposal, and economically so should anyone who owns Bitcoin. I=
=20
don't see any solid incentive-based motivation to let QCs "free up"=20
vulnerable coins, other than maybe as an early-warning indicator. This is=
=20
impossible to prove, but I personally believe almost all dormant bitcoins=
=20
that would be locked by phase B are already permanently lost (dead=20
addresses, dead owners, etc).

I do think we should delay phase B as long as we can, to give as many=20
people time to upgrade as possible. The time horizons should be flexible=20
and allow us to react to changes, in case practical quantum computers take=
=20
much more/less time to arrive than we expect today.

Commit/reveal protocols described in other mailing list threads are a=20
tempting way to rescue some quantum-vulnerable funds, without the=20
complexity of zk-STARKs... but these protocols would be difficult to=20
explain to users, and they only work for addresses whose pubkeys haven't=20
been exposed yet. This makes implementation hard. It rules out many=20
existing UTXOs, and all P2TR UTXOs too. At this point I don't feel=20
commit/reveal is worth the engineering effort and research given those=20
limitations. It's reasonable that you left these out of your proposal.

It's true that phase C would require a hard fork if we first deploy phase=
=20
B, because phase B explicitly closes the door on spending from pre-quantum=
=20
addresses. However, I believe zk-STARK proof unlocking could be executed as=
=20
a soft fork if you combine phases B and C together into a single upgrade.=
=20
This way, there is never a delta in the consensus rules in which EC=20
spending rules need to be relaxed.=20


   - *Before*: allow spending P2PKH if given a valid sig/pubkey.=20
   - *After*: allow spending P2PKH if given a valid sig/pubkey AND a valid=
=20
   ZK proof of seed-phrase-based key derivation (e.g. BIP39).=20
  =20

With this combined approach, we would never see a period of time in which=
=20
average users with mnemonic-seed wallets are locked out of their funds, and=
=20
we need no hard forks at all.

regards,
conduition
On Saturday, July 12th, 2025 at 5:46 PM, Jameson Lopp <jameso...@gmail.com>=
=20
wrote:

Building upon my earlier essay against allowing quantum recovery of bitcoin=
=20
<https://groups.google.com/g/bitcoindev/c/uUK6py0Yjq0/m/6peEaa90AQAJ> I=20
wish to formalize a proposal after several months of discussions.

This proposal does not delve into the multitude of issues regarding post=20
quantum cryptography and trade-offs of different schemes, but rather is=20
meant to specifically address the issues of incentivizing adoption and=20
migration of funds *after* consensus is established that it is prudent to=
=20
do so.

As such, this proposal requires P2QRH as described in BIP-360 or potential=
=20
future proposals.
Abstract

This proposal follows the implementation of post-quantum (PQ) output type=
=20
(P2QRH) and introduces a pre-announced sunset of legacy ECDSA/Schnorr=20
signatures. It turns quantum security into a private incentive: fail to=20
upgrade and you will certainly lose access to your funds, creating a=20
certainty where none previously existed.=20

   -=20
  =20
   Phase A: Disallows sending of any funds to quantum-vulnerable addresses,=
=20
   hastening the adoption of P2QRH address types.
   -=20
  =20
   Phase B: Renders ECDSA/Schnorr spends invalid, preventing all spending=
=20
   of funds in quantum-vulnerable UTXOs. This is triggered by a=20
   well-publicized flag-day roughly five years after activation.
   -=20
  =20
   Phase C (optional): Pending further research and demand, a separate BIP=
=20
   proposing a fork to allow recovery of legacy UTXOs through ZK proof of=
=20
   possession of BIP-39 seed phrase.=20
  =20
Motivation

We seek to secure the value of the UTXO set and minimize incentives for=20
quantum attacks. This proposal is radically different from any in Bitcoin=
=E2=80=99s=20
history just as the threat posed by quantum computing is radically=20
different from any other threat in Bitcoin=E2=80=99s history. Never before =
has=20
Bitcoin faced an existential threat to its cryptographic primitives. A=20
successful quantum attack on Bitcoin would result in significant economic=
=20
disruption and damage across the entire ecosystem. Beyond its impact on=20
price, the ability of miners to provide network security may be=20
significantly impacted.=20

   -=20
  =20
   Accelerating quantum progress.=20
   -=20
     =20
      NIST ratified three production-grade PQ signature schemes in 2024;=20
      academic road-maps now estimate a cryptographically-relevant quantum=
=20
      computer as early as 2027-2030. [McKinsey=20
      <https://www.mckinsey.com/~/media/mckinsey/business%20functions/mckin=
sey%20digital/our%20insights/the%20year%20of%20quantum%20from%20concept%20t=
o%20reality%20in%202025/quantum-monitor-2025.pdf?shouldIndex=3Dfalse>
      ]
      -=20
  =20
   Quantum algorithms are rapidly improving
   -=20
     =20
      The safety envelope is shrinking by dramatic increases in algorithms=
=20
      even if the pace of hardware improvements is slower. Algorithms are i=
mproving=20
      up to 20X=20
      <https://security.googleblog.com/2025/05/tracking-cost-of-quantum-fac=
tori.html>,=20
      lowering the theoretical hardware requirements for breaking classical=
=20
      encryption.
      -=20
  =20
   Bitcoin=E2=80=99s exposed public keys.=20
   -=20
     =20
      Roughly 25% of all bitcoin have revealed a public key on-chain; those=
=20
      UTXOs could be stolen with sufficient quantum power.=20
      -=20
  =20
   We may not know the attack is underway.=20
   -=20
     =20
      Quantum attackers could compute the private key for known public keys=
=20
      then transfer all funds weeks or months later, in a covert bleed to n=
ot=20
      alert chain watchers. Q-Day may be only known much later if the attac=
k=20
      withholds broadcasting transactions in order to postpone revealing th=
eir=20
      capabilities.
      -=20
  =20
   Private keys become public.=20
   -=20
     =20
      Assuming that quantum computers are able to maintain their current=20
      trajectories and overcome existing engineering obstacles, there is a =
near=20
      certain chance that all P2PK (and other outputs with exposed pubkeys)=
=20
      private keys will be found and used to steal the funds.
      -=20
  =20
   Impossible to know motivations.=20
   -=20
     =20
      Prior to a quantum attack, it is impossible to know the motivations=
=20
      of the attacker. An economically motivated attacker will try to remai=
n=20
      undetected for as long as possible, while a malicious attacker will a=
ttempt=20
      to destroy as much value as possible.=20
      -=20
  =20
   Upgrade inertia.=20
   -=20
     =20
      Coordinating wallets, exchanges, miners and custodians historically=
=20
      takes years.
      -=20
     =20
      The longer we postpone migration, the harder it becomes to coordinate=
=20
      wallets, exchanges, miners, and custodians. A clear, time-boxed pathw=
ay is=20
      the only credible defense.
      -=20
     =20
      Coordinating distributed groups is more prone to delay, even if=20
      everyone has similar motivations. Historically, Bitcoin has been slow=
 to=20
      adopt code changes, often taking multiple years to be approved.
     =20
Benefits at a Glance
  =20
   -=20
  =20
   Resilience: Bitcoin protocol remains secure for the foreseeable future=
=20
   without waiting for a last-minute emergency.
   -=20
  =20
   Certainty: Bitcoin users and stakeholders gain certainty that a plan is=
=20
   both in place and being implemented to effectively deal with the threat =
of=20
   quantum theft of bitcoin.=20
   -=20
  =20
   Clarity: A single, publicized timeline aligns the entire ecosystem=20
   (wallets, exchanges, hardware vendors).
   -=20
  =20
   Supply Discipline: Abandoned keys that never migrate become unspendable,=
=20
   reducing supply, as Satoshi described=20
   <https://bitcointalk.org/index.php?topic=3D198.msg1647#msg1647>.=20
  =20
Specification

Phase

What Happens

Who Must Act

Time Horizon

Phase A - Disallow spends to legacy script types

Permitted sends are from legacy scripts to P2QRH scripts

Everyone holding or accepting BTC.

3 years after BIP-360 implementation

Phase B =E2=80=93 Disallow spends from quantum vulnerable outputs

At a preset block-height, nodes reject transactions that rely on=20
ECDSA/Schnorr keys.=20

Everyone holding or accepting BTC.

2 years after Phase A activation.

Phase C =E2=80=93 Re-enable spends from quantum vulnerable outputs via ZK P=
roof

Users with frozen quantum vulnerable funds and a HD wallet seed phrase can=
=20
construct a quantum safe ZK proof to recover funds.

Users who failed to migrate funds before Phase B.

TBD pending research, demand, and consensus.
Rationale
  =20
   -=20
  =20
   Even if Bitcoin is not a primary initial target of a cryptographically=
=20
   relevant quantum computer, widespread knowledge that such a computer exi=
sts=20
   and is capable of breaking Bitcoin=E2=80=99s cryptography will damage fa=
ith in the=20
   network .=20
   -=20
  =20
   An attack on Bitcoin may not be economically motivated - an attacker may=
=20
   be politically or maliciously motivated and may attempt to destroy value=
=20
   and trust in Bitcoin rather than extract value. There is no way to know =
in=20
   advance how, when, or why an attack may occur. A defensive position must=
 be=20
   taken well in advance of any attack.=20
   -=20
  =20
   Bitcoin=E2=80=99s current signatures (ECDSA/Schnorr) will be a tantalizi=
ng=20
   target: any UTXO that has ever exposed its public key on-chain (roughly =
25=20
   % of all bitcoin) could be stolen by a cryptographically relevant quantu=
m=20
   computer.
   -=20
  =20
   Existing Proposals are Insufficient.=20
   1.=20
     =20
      Any proposal that allows for the quantum theft of =E2=80=9Clost=E2=80=
=9D bitcoin is=20
      creating a redistribution dilemma. There are 3 types of proposals:
      1.=20
        =20
         Allow anyone to steal vulnerable coins, benefitting those who=20
         reach quantum capability earliest.
         2.=20
        =20
         Allow throttled theft of coins, which leads to RBF battles and=20
         ultimately miners subsidizing their revenue from lost coins.
         3.=20
        =20
         Allow no one to steal vulnerable coins.
         -=20
  =20
   Minimizes attack surface
   1.=20
     =20
      By disallowing new spends to quantum vulnerable script types, we=20
      minimize the attack surface with each new UTXO.=20
      2.=20
     =20
      Upgrades to Bitcoin have historically taken many years; this will=20
      hasten and speed up the adoption of new quantum resistant script type=
s.=20
      3.=20
     =20
      With a clear deadline, industry stakeholders will more readily=20
      upgrade existing infrastructure to ensure continuity of services.=20
      -=20
  =20
   Minimizes loss of access to funds=20
   1.=20
     =20
      If there is sufficient demand and research proves possible,=20
      submitting a ZK proof of knowledge of a BIP-39 seed phrase correspond=
ing to=20
      a public key hash or script hash would provide a trustless means for =
legacy=20
      outputs to be spent in a quantum resistant manner, even after the sun=
set.=20
     =20

Stakeholder

Incentive to Upgrade

Miners

=E2=80=A2 Larger size PQ signatures along with incentive for users to migra=
te will=20
create more demand for block space and thus higher fees collected by miners=
.

=E2=80=A2 Post-Phase B, non-upgraded miners produce invalid blocks.

=E2=80=A2 A quantum attack on Bitcoin will significantly devalue both their=
=20
hardware and Bitcoin as a whole.=20

Institutional Holders

=E2=80=A2 Fiduciary duty: failing to act to prevent a quantum attack on Bit=
coin=20
would violate the fiduciary duty to shareholders.=20

=E2=80=A2 Demonstrating Bitcoin=E2=80=99s ability to effectively mitigate e=
merging threats=20
will prove Bitcoin to be an investment grade asset.

Exchanges & Custodians

=E2=80=A2 Concentrated risk: a quantum hack could bankrupt them overnight.

=E2=80=A2 Early migration is cheap relative to potential losses, potential =
lawsuits=20
over improper custody and reputational damage.

Everyday Users

=E2=80=A2 Self-sovereign peace of mind.

=E2=80=A2 Sunset date creates a clear deadline and incentive to improve the=
ir=20
security rather than an open-ended =E2=80=9Csome day=E2=80=9D that invites =
procrastination.

Attackers

=E2=80=A2 Economic incentive diminishes as sunset nears, stolen coins canno=
t be=20
spent after Q-day.

Key Insight: As mentioned earlier, the proposal turns quantum security into=
=20
a private incentive to upgrade.=20

This is not an offensive attack, rather, it is defensive: our thesis is=20
that the Bitcoin ecosystem wishes to defend itself and its interests=20
against those who would prefer to do nothing and allow a malicious actor to=
=20
destroy both value and trust.=20


"Lost coins only make everyone else's coins worth slightly more. Think of=
=20
it as a donation to everyone." - Satoshi Nakamoto


If true, the corollary is:


"Quantum recovered coins only make everyone else's coins worth less. Think=
=20
of it as a theft from everyone."


The timelines that we are proposing are meant to find the best balance=20
between giving ample ability for account owners to migrate while=20
maintaining the integrity of the overall ecosystem to avoid catastrophic=20
attacks.=20

Backward Compatibility

As a series of soft forks, older nodes will continue to operate without=20
modification. Non-upgraded nodes, however, will consider all post-quantum=
=20
witness programs as anyone-can-spend scripts. They are strongly encouraged=
=20
to upgrade in order to fully validate the new programs.

Non-upgraded wallets can receive and send bitcoin from non-upgraded and=20
upgraded wallets until Phase A. After Phase A, they can no longer receive=
=20
from any other wallets and can only send to upgraded wallets. After Phase=
=20
B, both senders and receivers will require upgraded wallets. Phase C would=
=20
likely require a loosening of consensus rules (a hard fork) to allow=20
vulnerable funds recovery via ZK proofs.

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------=_Part_103549_211251283.1752588818047
Content-Type: text/html; charset="UTF-8"
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<div>Hi Conduition, hi=C2=A0Jameson,=C2=A0hi all!</div><div><br /></div><di=
v>What if all vulnerable coins are temporarily locked during phase B, with =
a clearly defined future block height X (e.g., in 5-10 years) at which poin=
t these coins become EC-spendable again? This would give us time to develop=
 recovery mechanisms for phase C. It also wouldn't require a hard fork, sin=
ce the unlocking height X would already be part of the consensus rules intr=
oduced in phase B. In this way, we avoid a hard fork altogether. Instead of=
 permanent freezing, a forced timelock would be applied to vulnerable outpu=
ts.</div><br />Beyond merely avoiding a hard fork, this approach offers add=
itional benefits. It improves the situation for owners of vulnerable coins =
who missed the initial deadline, since a timelock is preferable to permanen=
t freezing. To be clear, I am not advocating for locking the coins -- even=
=20
temporarily. However, if a choice must be made, temporary locking is=20
clearly preferable to permanent freezing. Developers working on recovery me=
chanisms would have a clear timeline and incentive to deliver phase C as a =
subsequent soft fork. At the same time, the community gains valuable time f=
or data-driven decision-making -- allowing us to adapt based on how events =
unfold, including whether legitimate claims are made on locked coins, and b=
ased on future developments in quantum computing.<br /><br /><div>This assu=
mes that phases A and B are deployed before a real quantum threat materiali=
zes. If, in the meantime, fundamental research concludes that quantum compu=
ting will not break EC for the next 100 years, we can simply do nothing -- =
and the coins will unlock automatically at height X. On the other hand, if =
quantum computing advances significantly, we can respond based on the avail=
ability and quality of recovery schemes: either deploy a recovery soft fork=
 at block X, or apply another soft fork to postpone unlocking by another 5-=
10 years.</div><div><br /></div><div></div><div>Best,</div><div>Boris</div>=
<div><br /></div><div><div dir=3D"auto">On Tuesday, July 15, 2025 at 8:36:3=
3=E2=80=AFAM UTC-3 conduition wrote:<br /></div><blockquote style=3D"margin=
: 0px 0px 0px 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-lef=
t: 1ex;"><div style=3D"font-family: Arial, sans-serif; font-size: 14px;">Hi=
 Jameson,</div><div style=3D"font-family: Arial, sans-serif; font-size: 14p=
x;"><br /></div><div style=3D"font-family: Arial, sans-serif; font-size: 14=
px;">I like your proposal, and economically so should anyone who owns Bitco=
in. I don't see any solid incentive-based motivation to let QCs "free up" v=
ulnerable coins, other than maybe as an early-warning indicator. This is im=
possible to prove, but I personally believe almost all dormant bitcoins tha=
t would be locked by phase B are already permanently lost (dead addresses, =
dead owners, etc).</div><div style=3D"font-family: Arial, sans-serif; font-=
size: 14px;"><br /></div><div style=3D"font-family: Arial, sans-serif; font=
-size: 14px;">I do think we should delay phase B as long as we can, to give=
 as many people time to upgrade as possible. The time horizons should be fl=
exible and allow us to react to changes, in case practical quantum computer=
s take much more/less time to arrive than we expect today.</div><div style=
=3D"font-family: Arial, sans-serif; font-size: 14px;"><br /></div><div styl=
e=3D"font-family: Arial, sans-serif; font-size: 14px;">Commit/reveal protoc=
ols described in other mailing list threads are a tempting way to rescue so=
me quantum-vulnerable funds, without the complexity of zk-STARKs... but the=
se protocols would be difficult to explain to users, and they only work for=
 addresses whose pubkeys haven't been exposed yet. This makes implementatio=
n hard. It rules out many existing UTXOs, and all P2TR UTXOs too. At this p=
oint I don't feel commit/reveal is worth the engineering effort and researc=
h given those limitations. It's reasonable that you left these out of your =
proposal.</div><div style=3D"font-family: Arial, sans-serif; font-size: 14p=
x;"><br /></div><div style=3D"font-family: Arial, sans-serif; font-size: 14=
px;">It's true that phase C would require a hard fork if we first deploy ph=
ase B, because phase B explicitly closes the door on spending from pre-quan=
tum addresses. However,=C2=A0<span>I believe zk-STARK proof unlocking could=
 be executed as a soft fork if you combine phases B and C together into a s=
ingle upgrade. This way, there is never a delta in the consensus rules in w=
hich EC spending rules need to be relaxed.=C2=A0</span></div><div style=3D"=
font-family: Arial, sans-serif; font-size: 14px;"><span><br /></span></div>=
<div style=3D"font-family: Arial, sans-serif; font-size: 14px;"><ul style=
=3D"margin-top: 0px; margin-bottom: 0px;"><li style=3D"list-style-type: &qu=
ot;- &quot;;"><span><span><b>Before</b>: allow spending P2PKH if given a va=
lid sig/pubkey.=C2=A0</span></span></li><li style=3D"list-style-type: &quot=
;- &quot;;"><span><span><b>After</b>: allow spending P2PKH if given a valid=
 sig/pubkey AND a valid ZK proof of seed-phrase-based key derivation (e.g. =
BIP39).=C2=A0</span><br /></span></li></ul></div><div style=3D"font-family:=
 Arial, sans-serif; font-size: 14px;"><span><br /></span></div><div style=
=3D"font-family: Arial, sans-serif; font-size: 14px;"><span>With this combi=
ned approach, we would never see a period of time in which average users wi=
th mnemonic-seed wallets are locked out of their funds, and we need no hard=
 forks at all.</span></div><div style=3D"font-family: Arial, sans-serif; fo=
nt-size: 14px;"><span><br /></span></div><div style=3D"font-family: Arial, =
sans-serif; font-size: 14px;"><span>regards,</span></div><div style=3D"font=
-family: Arial, sans-serif; font-size: 14px;"><span>conduition</span></div>=
<div style=3D"font-family: Arial, sans-serif; font-size: 14px;"><span></spa=
n></div><div></div><div>
        On Saturday, July 12th, 2025 at 5:46 PM, Jameson Lopp &lt;<a href=
=3D"" rel=3D"nofollow">jameso...@gmail.com</a>&gt; wrote:<br />
        </div><div><blockquote type=3D"cite">
            <div dir=3D"ltr"><span><p dir=3D"ltr" style=3D"line-height: 1.4=
4; background-color: rgb(255, 255, 255); margin-top: 12pt; margin-bottom: 0=
pt; padding: 0pt 0pt 12pt;"><span style=3D"font-size: 11pt; font-family: &q=
uot;Courier New&quot;, monospace; color: rgb(34, 34, 34); background-color:=
 transparent; font-weight: 400; font-style: normal; font-variant: normal; t=
ext-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Bui=
lding upon my earlier essay </span><a href=3D"https://groups.google.com/g/b=
itcoindev/c/uUK6py0Yjq0/m/6peEaa90AQAJ" style=3D"text-decoration: none;" re=
l=3D"noreferrer nofollow noopener" target=3D"_blank"><span style=3D"font-si=
ze: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(17, 8=
5, 204); background-color: transparent; font-weight: 400; font-style: norma=
l; font-variant: normal; text-decoration: underline; vertical-align: baseli=
ne; white-space: pre-wrap;">against allowing quantum recovery of bitcoin</s=
pan></a><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot=
;, monospace; color: rgb(34, 34, 34); background-color: transparent; font-w=
eight: 400; font-style: normal; font-variant: normal; text-decoration: none=
; vertical-align: baseline; white-space: pre-wrap;"> I wish to formalize a =
proposal after several months of discussions.</span></p><p dir=3D"ltr" styl=
e=3D"line-height: 1.44; background-color: rgb(255, 255, 255); margin-top: 0=
pt; margin-bottom: 0pt; padding: 0pt 0pt 12pt;"><span style=3D"font-size: 1=
1pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(34, 34, 34=
); background-color: transparent; font-weight: 400; font-style: normal; fon=
t-variant: normal; text-decoration: none; vertical-align: baseline; white-s=
pace: pre-wrap;">This proposal does not delve into the multitude of issues =
regarding post quantum cryptography and trade-offs of different schemes, bu=
t rather is meant to specifically address the issues of incentivizing adopt=
ion and migration of funds </span><span style=3D"font-size: 11pt; font-fami=
ly: &quot;Courier New&quot;, monospace; color: rgb(34, 34, 34); background-=
color: transparent; font-weight: 400; font-variant: normal; text-decoration=
: none; vertical-align: baseline; white-space: pre-wrap;"><i>after</i></spa=
n><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, mon=
ospace; color: rgb(34, 34, 34); background-color: transparent; font-weight:=
 400; font-style: normal; font-variant: normal; text-decoration: none; vert=
ical-align: baseline; white-space: pre-wrap;"> consensus is established tha=
t it is prudent to do so.</span></p><p dir=3D"ltr" style=3D"line-height: 1.=
44; background-color: rgb(255, 255, 255); margin-top: 0pt; margin-bottom: 1=
2pt;"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;,=
 monospace; color: rgb(0, 0, 0); background-color: transparent; font-weight=
: 400; font-style: normal; font-variant: normal; text-decoration: none; ver=
tical-align: baseline; white-space: pre-wrap;">As such, this proposal requi=
res P2QRH as described in BIP-360 or potential future proposals.</span></p>=
<span dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 18pt; margin-bott=
om: 4pt;"><span style=3D"font-size: 17pt; font-family: &quot;Courier New&qu=
ot;, monospace; color: rgb(0, 0, 0); background-color: transparent; font-va=
riant-numeric: normal; font-variant-east-asian: normal; font-variant-altern=
ates: normal; vertical-align: baseline;">Abstract</span></span><p dir=3D"lt=
r" style=3D"line-height: 1.38; margin-top: 12pt; margin-bottom: 12pt;"><spa=
n style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace=
; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric:=
 normal; font-variant-east-asian: normal; font-variant-alternates: normal; =
vertical-align: baseline;">This proposal follows the implementation of post=
-quantum (PQ) output type (P2QRH) and introduces a pre-announced sunset of =
legacy ECDSA/Schnorr signatures. It turns quantum security into a </span><s=
pan style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospa=
ce; color: rgb(0, 0, 0); background-color: transparent; font-style: italic;=
 font-variant-numeric: normal; font-variant-east-asian: normal; font-varian=
t-alternates: normal; vertical-align: baseline;">private incentive</span><s=
pan style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospa=
ce; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeri=
c: normal; font-variant-east-asian: normal; font-variant-alternates: normal=
; vertical-align: baseline;">: fail to upgrade and you will certainly lose =
access to your funds, creating a certainty where none previously existed. <=
/span></p><ul style=3D"margin-top: 0px; margin-bottom: 0px;"><li dir=3D"ltr=
" style=3D"list-style-type: disc; font-size: 11pt; font-family: &quot;Couri=
er New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent=
; font-variant-numeric: normal; font-variant-east-asian: normal; font-varia=
nt-alternates: normal; vertical-align: baseline; white-space: pre-wrap;"><p=
 dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0p=
t;" role=3D"presentation"><span style=3D"font-size: 11pt; background-color:=
 transparent; font-weight: 700; font-variant-numeric: normal; font-variant-=
east-asian: normal; font-variant-alternates: normal; vertical-align: baseli=
ne;">Phase A:</span><span style=3D"font-size: 11pt; background-color: trans=
parent; font-variant-numeric: normal; font-variant-east-asian: normal; font=
-variant-alternates: normal; vertical-align: baseline;"> Disallows sending =
of any funds to quantum-vulnerable addresses, hastening the adoption of P2Q=
RH address types.</span></p></li><li dir=3D"ltr" style=3D"list-style-type: =
disc; font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; col=
or: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: norm=
al; font-variant-east-asian: normal; font-variant-alternates: normal; verti=
cal-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-h=
eight: 1.38; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><s=
pan style=3D"font-size: 11pt; background-color: transparent; font-weight: 7=
00; font-variant-numeric: normal; font-variant-east-asian: normal; font-var=
iant-alternates: normal; vertical-align: baseline;">Phase B:</span><span st=
yle=3D"font-size: 11pt; background-color: transparent; font-variant-numeric=
: normal; font-variant-east-asian: normal; font-variant-alternates: normal;=
 vertical-align: baseline;"> Renders ECDSA/Schnorr spends invalid, preventi=
ng all spending of funds in quantum-vulnerable UTXOs. This is triggered by =
a well-publicized flag-day roughly five years after activation.</span></p><=
/li><li dir=3D"ltr" style=3D"list-style-type: disc; font-size: 11pt; font-f=
amily: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-=
color: transparent; font-variant-numeric: normal; font-variant-east-asian: =
normal; font-variant-alternates: normal; vertical-align: baseline; white-sp=
ace: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt;=
 margin-bottom: 6pt;" role=3D"presentation"><span style=3D"font-size: 11pt;=
 background-color: transparent; font-weight: 700; font-variant-numeric: nor=
mal; font-variant-east-asian: normal; font-variant-alternates: normal; vert=
ical-align: baseline;">Phase C (optional):</span><span style=3D"font-size: =
11pt; background-color: transparent; font-variant-numeric: normal; font-var=
iant-east-asian: normal; font-variant-alternates: normal; vertical-align: b=
aseline;"> Pending further research and demand, a separate BIP proposing a =
fork to allow recovery of legacy UTXOs through ZK proof of possession of BI=
P-39 seed phrase.  </span></p></li></ul><span dir=3D"ltr" style=3D"line-hei=
ght: 1.38; text-align: justify; margin-top: 14pt; margin-bottom: 6pt;"><spa=
n style=3D"font-size: 16pt; font-family: &quot;Courier New&quot;, monospace=
; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric:=
 normal; font-variant-east-asian: normal; font-variant-alternates: normal; =
vertical-align: baseline;">Motivation</span></span><p dir=3D"ltr" style=3D"=
line-height: 1.38; text-align: justify; margin-top: 12pt; margin-bottom: 12=
pt;"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, =
monospace; color: rgb(0, 0, 0); background-color: transparent; font-variant=
-numeric: normal; font-variant-east-asian: normal; font-variant-alternates:=
 normal; vertical-align: baseline;">We seek to secure the value of the UTXO=
 set</span><span style=3D"font-size: 11pt; font-family: &quot;Courier New&q=
uot;, monospace; color: rgb(0, 0, 0); background-color: transparent; font-w=
eight: 700; font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-alternates: normal; vertical-align: baseline;"> </span><span s=
tyle=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; c=
olor: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: no=
rmal; font-variant-east-asian: normal; font-variant-alternates: normal; ver=
tical-align: baseline;">and minimize incentives for quantum attacks. This p=
roposal is radically different from any in Bitcoin=E2=80=99s history just a=
s the threat posed by quantum computing is radically different from any oth=
er threat in Bitcoin=E2=80=99s history.  Never before has Bitcoin faced an =
existential threat to its cryptographic primitives. A successful quantum at=
tack on Bitcoin would result in significant economic disruption and damage =
across the entire ecosystem. Beyond its impact on price, the ability of min=
ers to provide network security may be significantly impacted.  </span></p>=
<ul style=3D"margin-top: 0px; margin-bottom: 0px;"><li dir=3D"ltr" style=3D=
"list-style-type: disc; font-size: 11pt; font-family: &quot;Courier New&quo=
t;, monospace; color: rgb(0, 0, 0); background-color: transparent; font-var=
iant-numeric: normal; font-variant-east-asian: normal; font-variant-alterna=
tes: normal; vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"lt=
r" style=3D"line-height: 1.38; margin-top: 12pt; margin-bottom: 0pt;" role=
=3D"presentation"><span style=3D"font-size: 11pt; background-color: transpa=
rent; font-weight: 700; font-variant-numeric: normal; font-variant-east-asi=
an: normal; font-variant-alternates: normal; vertical-align: baseline;">Acc=
elerating quantum progress.</span><span style=3D"font-size: 11pt; backgroun=
d-color: transparent; font-variant-numeric: normal; font-variant-east-asian=
: normal; font-variant-alternates: normal; vertical-align: baseline;"> </sp=
an></p><ul style=3D"margin-top: 0px; margin-bottom: 0px;"><li dir=3D"ltr" s=
tyle=3D"list-style-type: circle; font-size: 11pt; font-family: &quot;Courie=
r New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent;=
 font-variant-numeric: normal; font-variant-east-asian: normal; font-varian=
t-alternates: normal; vertical-align: baseline; white-space: pre-wrap;"><p =
dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt=
;" role=3D"presentation"><span style=3D"font-size: 11pt; background-color: =
transparent; font-variant-numeric: normal; font-variant-east-asian: normal;=
 font-variant-alternates: normal; vertical-align: baseline;">NIST ratified =
three production-grade PQ signature schemes in 2024; academic road-maps now=
 estimate a cryptographically-relevant quantum computer as early as 2027-20=
30. [</span><a href=3D"https://www.mckinsey.com/~/media/mckinsey/business%2=
0functions/mckinsey%20digital/our%20insights/the%20year%20of%20quantum%20fr=
om%20concept%20to%20reality%20in%202025/quantum-monitor-2025.pdf?shouldInde=
x=3Dfalse" style=3D"text-decoration-line: none;" rel=3D"noreferrer nofollow=
 noopener" target=3D"_blank"><span style=3D"font-size: 11pt; background-col=
or: transparent; font-variant-numeric: normal; font-variant-east-asian: nor=
mal; font-variant-alternates: normal; text-decoration-line: underline; vert=
ical-align: baseline;">McKinsey</span></a><span style=3D"font-size: 11pt; b=
ackground-color: transparent; font-variant-numeric: normal; font-variant-ea=
st-asian: normal; font-variant-alternates: normal; vertical-align: baseline=
;">]</span></p></li></ul></li><li dir=3D"ltr" style=3D"list-style-type: dis=
c; font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color:=
 rgb(0, 0, 0); background-color: transparent; font-weight: 700; font-varian=
t-numeric: normal; font-variant-east-asian: normal; font-variant-alternates=
: normal; vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" =
style=3D"line-height: 1.38; text-align: justify; margin-top: 0pt; margin-bo=
ttom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt; backgroun=
d-color: transparent; font-variant-numeric: normal; font-variant-east-asian=
: normal; font-variant-alternates: normal; vertical-align: baseline;">Quant=
um algorithms are rapidly improving</span></p><ul style=3D"margin-top: 0px;=
 margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: circle; fon=
t-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0=
, 0, 0); background-color: transparent; font-variant-numeric: normal; font-=
variant-east-asian: normal; font-variant-alternates: normal; vertical-align=
: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.=
38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt;" role=3D"pres=
entation"><span style=3D"font-size: 11pt; background-color: transparent; fo=
nt-variant-numeric: normal; font-variant-east-asian: normal; font-variant-a=
lternates: normal; vertical-align: baseline;">The safety envelope is shrink=
ing by dramatic increases in algorithms even if the pace of hardware improv=
ements is slower. Algorithms are <a href=3D"https://security.googleblog.com=
/2025/05/tracking-cost-of-quantum-factori.html" rel=3D"noreferrer nofollow =
noopener" target=3D"_blank">improving up to 20X</a>, lowering the theoretic=
al hardware requirements for breaking classical encryption.</span></p></li>=
</ul></li><li dir=3D"ltr" style=3D"list-style-type: disc; font-size: 11pt; =
font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); backg=
round-color: transparent; font-variant-numeric: normal; font-variant-east-a=
sian: normal; font-variant-alternates: normal; vertical-align: baseline; wh=
ite-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top=
: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-size:=
 11pt; background-color: transparent; font-weight: 700; font-variant-numeri=
c: normal; font-variant-east-asian: normal; font-variant-alternates: normal=
; vertical-align: baseline;">Bitcoin=E2=80=99s exposed public keys.</span><=
span style=3D"font-size: 11pt; background-color: transparent; font-variant-=
numeric: normal; font-variant-east-asian: normal; font-variant-alternates: =
normal; vertical-align: baseline;"> </span></p><ul style=3D"margin-top: 0px=
; margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: circle; fo=
nt-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(=
0, 0, 0); background-color: transparent; font-variant-numeric: normal; font=
-variant-east-asian: normal; font-variant-alternates: normal; vertical-alig=
n: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1=
.38; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span styl=
e=3D"font-size: 11pt; background-color: transparent; font-variant-numeric: =
normal; font-variant-east-asian: normal; font-variant-alternates: normal; v=
ertical-align: baseline;">Roughly 25% of all bitcoin have revealed a public=
 key on-chain; those UTXOs could be stolen with sufficient quantum power.  =
</span></p></li></ul></li><li dir=3D"ltr" style=3D"list-style-type: disc; f=
ont-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb=
(0, 0, 0); background-color: transparent; font-variant-numeric: normal; fon=
t-variant-east-asian: normal; font-variant-alternates: normal; vertical-ali=
gn: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: =
1.38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt;" role=3D"pr=
esentation"><span style=3D"font-size: 11pt; background-color: transparent; =
font-weight: 700; font-variant-numeric: normal; font-variant-east-asian: no=
rmal; font-variant-alternates: normal; vertical-align: baseline;">We may no=
t know the attack is underway. </span></p><ul style=3D"margin-top: 0px; mar=
gin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: circle; font-si=
ze: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0,=
 0); background-color: transparent; font-variant-numeric: normal; font-vari=
ant-east-asian: normal; font-variant-alternates: normal; vertical-align: ba=
seline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; =
text-align: justify; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presenta=
tion"><span style=3D"font-size: 11pt; background-color: transparent; font-v=
ariant-numeric: normal; font-variant-east-asian: normal; font-variant-alter=
nates: normal; vertical-align: baseline;">Quantum attackers could compute t=
he private key for known public keys then transfer all funds weeks or month=
s later, in a covert bleed to not alert chain watchers. Q-Day may be only k=
nown much later if the attack withholds broadcasting transactions in order =
to postpone revealing their capabilities.</span></p></li></ul></li><li dir=
=3D"ltr" style=3D"list-style-type: disc; font-size: 11pt; font-family: &quo=
t;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: tran=
sparent; font-weight: 700; font-variant-numeric: normal; font-variant-east-=
asian: normal; font-variant-alternates: normal; vertical-align: baseline; w=
hite-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-to=
p: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-size=
: 11pt; background-color: transparent; font-variant-numeric: normal; font-v=
ariant-east-asian: normal; font-variant-alternates: normal; vertical-align:=
 baseline;">Private keys become public. </span></p><ul style=3D"margin-top:=
 0px; margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: circle=
; font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color: =
rgb(0, 0, 0); background-color: transparent; font-weight: 700; font-variant=
-numeric: normal; font-variant-east-asian: normal; font-variant-alternates:=
 normal; vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" s=
tyle=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" role=3D"pr=
esentation"><span style=3D"font-size: 11pt; background-color: transparent; =
font-weight: 400; font-variant-numeric: normal; font-variant-east-asian: no=
rmal; font-variant-alternates: normal; vertical-align: baseline;">Assuming =
that quantum computers are able to maintain their current trajectories and =
overcome existing engineering obstacles, there is a near certain chance tha=
t all P2PK (and other outputs with exposed pubkeys) private keys will be fo=
und and used to steal the funds.</span></p></li></ul></li><li dir=3D"ltr" s=
tyle=3D"list-style-type: disc; font-size: 11pt; font-family: &quot;Courier =
New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; f=
ont-weight: 700; font-variant-numeric: normal; font-variant-east-asian: nor=
mal; font-variant-alternates: normal; vertical-align: baseline; white-space=
: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; ma=
rgin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt; ba=
ckground-color: transparent; font-variant-numeric: normal; font-variant-eas=
t-asian: normal; font-variant-alternates: normal; vertical-align: baseline;=
">Impossible to know motivations. </span></p><ul style=3D"margin-top: 0px; =
margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: circle; font=
-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0,=
 0, 0); background-color: transparent; font-weight: 700; font-variant-numer=
ic: normal; font-variant-east-asian: normal; font-variant-alternates: norma=
l; vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=
=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presen=
tation"><span style=3D"font-size: 11pt; background-color: transparent; font=
-weight: 400; font-variant-numeric: normal; font-variant-east-asian: normal=
; font-variant-alternates: normal; vertical-align: baseline;">Prior to a qu=
antum attack, it is impossible to know the motivations of the attacker.  An=
 economically motivated attacker will try to remain undetected for as long =
as possible, while a malicious attacker will attempt to destroy as much val=
ue as possible.  </span></p></li></ul></li><li dir=3D"ltr" style=3D"list-st=
yle-type: disc; font-size: 11pt; font-family: &quot;Courier New&quot;, mono=
space; color: rgb(0, 0, 0); background-color: transparent; font-variant-num=
eric: normal; font-variant-east-asian: normal; font-variant-alternates: nor=
mal; vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=
=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presen=
tation"><span style=3D"font-size: 11pt; background-color: transparent; font=
-weight: 700; font-variant-numeric: normal; font-variant-east-asian: normal=
; font-variant-alternates: normal; vertical-align: baseline;">Upgrade inert=
ia.</span><span style=3D"font-size: 11pt; background-color: transparent; fo=
nt-variant-numeric: normal; font-variant-east-asian: normal; font-variant-a=
lternates: normal; vertical-align: baseline;"> </span></p><ul style=3D"marg=
in-top: 0px; margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-type:=
 circle; font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; =
color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: n=
ormal; font-variant-east-asian: normal; font-variant-alternates: normal; ve=
rtical-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"lin=
e-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"=
><span style=3D"font-size: 11pt; background-color: transparent; font-varian=
t-numeric: normal; font-variant-east-asian: normal; font-variant-alternates=
: normal; vertical-align: baseline;">Coordinating wallets, exchanges, miner=
s and custodians historically takes years.</span></p></li><li dir=3D"ltr" s=
tyle=3D"list-style-type: circle; font-size: 11pt; font-family: &quot;Courie=
r New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent;=
 font-variant-numeric: normal; font-variant-east-asian: normal; font-varian=
t-alternates: normal; vertical-align: baseline; white-space: pre-wrap;"><p =
dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 0p=
t; margin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11p=
t; background-color: transparent; font-variant-numeric: normal; font-varian=
t-east-asian: normal; font-variant-alternates: normal; vertical-align: base=
line;">The longer we postpone migration, the harder it becomes to coordinat=
e wallets, exchanges, miners, and custodians. A clear, time-boxed pathway i=
s the only credible defense.</span></p></li><li dir=3D"ltr" style=3D"list-s=
tyle-type: circle; font-size: 11pt; font-family: &quot;Courier New&quot;, m=
onospace; color: rgb(0, 0, 0); background-color: transparent; font-variant-=
numeric: normal; font-variant-east-asian: normal; font-variant-alternates: =
normal; vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" st=
yle=3D"line-height: 1.38; text-align: justify; margin-top: 0pt; margin-bott=
om: 12pt;" role=3D"presentation"><span style=3D"font-size: 11pt; background=
-color: transparent; font-variant-numeric: normal; font-variant-east-asian:=
 normal; font-variant-alternates: normal; vertical-align: baseline;">Coordi=
nating distributed groups is more prone to delay, even if everyone has simi=
lar motivations. Historically, Bitcoin has been slow to adopt code changes,=
 often taking multiple years to be approved.</span></p></li></ul></li></ul>=
<span dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-t=
op: 14pt; margin-bottom: 6pt;"><span style=3D"font-size: 16pt; font-family:=
 &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color:=
 transparent; font-variant-numeric: normal; font-variant-east-asian: normal=
; font-variant-alternates: normal; vertical-align: baseline;">Benefits at a=
 Glance</span></span><ul style=3D"margin-top: 0px; margin-bottom: 0px;"><li=
 dir=3D"ltr" style=3D"list-style-type: disc; font-size: 11pt; font-family: =
Arial, sans-serif; color: rgb(0, 0, 0); background-color: transparent; font=
-variant-numeric: normal; font-variant-east-asian: normal; font-variant-alt=
ernates: normal; vertical-align: baseline; white-space: pre-wrap;"><p dir=
=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 12pt;=
 margin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt;=
 font-family: &quot;Courier New&quot;, monospace; background-color: transpa=
rent; font-weight: 700; font-variant-numeric: normal; font-variant-east-asi=
an: normal; font-variant-alternates: normal; vertical-align: baseline;">Res=
ilience:</span><span style=3D"font-size: 11pt; font-family: &quot;Courier N=
ew&quot;, monospace; background-color: transparent; font-variant-numeric: n=
ormal; font-variant-east-asian: normal; font-variant-alternates: normal; ve=
rtical-align: baseline;"> Bitcoin protocol remains secure for the foreseeab=
le future without waiting for a last-minute emergency.</span></p></li><li d=
ir=3D"ltr" style=3D"list-style-type: disc; font-size: 11pt; font-family: Ar=
ial, sans-serif; color: rgb(0, 0, 0); background-color: transparent; font-v=
ariant-numeric: normal; font-variant-east-asian: normal; font-variant-alter=
nates: normal; vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"=
ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 0pt; marg=
in-bottom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt; font=
-family: &quot;Courier New&quot;, monospace; background-color: transparent;=
 font-weight: 700; font-variant-numeric: normal; font-variant-east-asian: n=
ormal; font-variant-alternates: normal; vertical-align: baseline;">Certaint=
y</span><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot=
;, monospace; background-color: transparent; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-alternates: normal; vertical-=
align: baseline;">: Bitcoin users and stakeholders gain certainty that a pl=
an is both in place and being implemented to effectively deal with the thre=
at of quantum theft of bitcoin.  </span></p></li><li dir=3D"ltr" style=3D"l=
ist-style-type: disc; font-size: 11pt; font-family: Arial, sans-serif; colo=
r: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: norma=
l; font-variant-east-asian: normal; font-variant-alternates: normal; vertic=
al-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-he=
ight: 1.38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt;" role=
=3D"presentation"><span style=3D"font-size: 11pt; font-family: &quot;Courie=
r New&quot;, monospace; background-color: transparent; font-weight: 700; fo=
nt-variant-numeric: normal; font-variant-east-asian: normal; font-variant-a=
lternates: normal; vertical-align: baseline;">Clarity:</span><span style=3D=
"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; backgrou=
nd-color: transparent; font-variant-numeric: normal; font-variant-east-asia=
n: normal; font-variant-alternates: normal; vertical-align: baseline;"> A s=
ingle, publicized timeline aligns the entire ecosystem (wallets, exchanges,=
 hardware vendors).</span></p></li><li dir=3D"ltr" style=3D"list-style-type=
: disc; font-size: 11pt; font-family: Arial, sans-serif; color: rgb(0, 0, 0=
); background-color: transparent; font-variant-numeric: normal; font-varian=
t-east-asian: normal; font-variant-alternates: normal; vertical-align: base=
line; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; te=
xt-align: justify; margin-top: 0pt; margin-bottom: 12pt;" role=3D"presentat=
ion"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, =
monospace; background-color: transparent; font-weight: 700; font-variant-nu=
meric: normal; font-variant-east-asian: normal; font-variant-alternates: no=
rmal; vertical-align: baseline;">Supply Discipline:</span><span style=3D"fo=
nt-size: 11pt; font-family: &quot;Courier New&quot;, monospace; background-=
color: transparent; font-variant-numeric: normal; font-variant-east-asian: =
normal; font-variant-alternates: normal; vertical-align: baseline;"> Abando=
ned keys that never migrate become unspendable, reducing supply, <a href=3D=
"https://bitcointalk.org/index.php?topic=3D198.msg1647#msg1647" rel=3D"nore=
ferrer nofollow noopener" target=3D"_blank">as Satoshi described</a></span>=
<span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monos=
pace; background-color: transparent; font-variant-numeric: normal; font-var=
iant-east-asian: normal; font-variant-alternates: normal; vertical-align: b=
aseline;">.  </span></p></li></ul><span dir=3D"ltr" style=3D"line-height: 1=
.38; text-align: justify; margin-top: 12pt; margin-bottom: 12pt;"><span sty=
le=3D"font-size: 16pt; font-family: &quot;Courier New&quot;, monospace; col=
or: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: norm=
al; font-variant-east-asian: normal; font-variant-alternates: normal; verti=
cal-align: baseline;">Specification</span></span><span dir=3D"ltr" style=3D=
"line-height: 1.38; text-align: justify; margin-top: 12pt; margin-bottom: 1=
2pt;"><span style=3D"font-weight: normal;"><div dir=3D"ltr" style=3D"margin=
-left: 0pt;" align=3D"left"><span style=3D"border: medium; border-collapse:=
 collapse;"><span><span width=3D"181"></span><span width=3D"224"></span><sp=
an width=3D"137"></span><span width=3D"130"></span></span><span><span style=
=3D"height: 0pt;"><span style=3D"border-width: 1pt; border-style: solid; bo=
rder-color: rgb(0, 0, 0); vertical-align: top; padding: 5pt; overflow: hidd=
en;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: center; margin-=
top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-family:=
 &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color:=
 transparent; font-weight: 700; font-variant-numeric: normal; font-variant-=
east-asian: normal; font-variant-alternates: normal; vertical-align: baseli=
ne;">Phase</span></p></span><span style=3D"border-width: 1pt; border-style:=
 solid; border-color: rgb(0, 0, 0); vertical-align: top; padding: 5pt; over=
flow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: cente=
r; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; fo=
nt-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); backgro=
und-color: transparent; font-weight: 700; font-variant-numeric: normal; fon=
t-variant-east-asian: normal; font-variant-alternates: normal; vertical-ali=
gn: baseline;">What Happens</span></p></span><span style=3D"border-width: 1=
pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align: top; p=
adding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; =
text-align: center; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"fo=
nt-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(=
0, 0, 0); background-color: transparent; font-weight: 700; font-variant-num=
eric: normal; font-variant-east-asian: normal; font-variant-alternates: nor=
mal; vertical-align: baseline;">Who Must Act</span></p></span><span style=
=3D"border-width: 1pt; border-style: solid; border-color: rgb(0, 0, 0); ver=
tical-align: top; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"=
line-height: 1.38; text-align: center; margin-top: 0pt; margin-bottom: 0pt;=
"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, mon=
ospace; color: rgb(0, 0, 0); background-color: transparent; font-weight: 70=
0; font-variant-numeric: normal; font-variant-east-asian: normal; font-vari=
ant-alternates: normal; vertical-align: baseline;">Time Horizon</span></p><=
/span></span><span style=3D"height: 0pt;"><span style=3D"border-width: 1pt;=
 border-style: solid; border-color: rgb(0, 0, 0); vertical-align: top; padd=
ing: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; mar=
gin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-fam=
ily: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-co=
lor: transparent; font-weight: 700; font-variant-numeric: normal; font-vari=
ant-east-asian: normal; font-variant-alternates: normal; vertical-align: ba=
seline;">Phase A - </span><span style=3D"font-size: 11pt; font-family: &quo=
t;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: tran=
sparent; font-variant-numeric: normal; font-variant-east-asian: normal; fon=
t-variant-alternates: normal; vertical-align: baseline;">Disallow spends to=
 legacy script types</span></p></span><span style=3D"border-width: 1pt; bor=
der-style: solid; border-color: rgb(0, 0, 0); vertical-align: middle; paddi=
ng: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; marg=
in-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 10pt; font-fami=
ly: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-col=
or: transparent; font-variant-numeric: normal; font-variant-east-asian: nor=
mal; font-variant-alternates: normal; vertical-align: baseline;">Permitted =
sends are from legacy scripts to P2QRH scripts</span></p></span><span style=
=3D"border-width: 1pt; border-style: solid; border-color: rgb(0, 0, 0); ver=
tical-align: middle; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=
=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D=
"font-size: 10pt; font-family: &quot;Courier New&quot;, monospace; color: r=
gb(0, 0, 0); background-color: transparent; font-style: italic; font-varian=
t-numeric: normal; font-variant-east-asian: normal; font-variant-alternates=
: normal; vertical-align: baseline;">Everyone</span><span style=3D"font-siz=
e: 10pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, =
0); background-color: transparent; font-variant-numeric: normal; font-varia=
nt-east-asian: normal; font-variant-alternates: normal; vertical-align: bas=
eline;"> holding or accepting BTC.</span></p></span><span style=3D"border-w=
idth: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align:=
 middle; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-heig=
ht: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 1=
0pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); =
background-color: transparent; font-variant-numeric: normal; font-variant-e=
ast-asian: normal; font-variant-alternates: normal; vertical-align: baselin=
e;">3 years after BIP-360 implementation</span></p></span></span><span styl=
e=3D"height: 0pt;"><span style=3D"border-width: 1pt; border-style: solid; b=
order-color: rgb(0, 0, 0); vertical-align: top; padding: 5pt; overflow: hid=
den;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bo=
ttom: 0pt;"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&=
quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; font-=
weight: 700; font-variant-numeric: normal; font-variant-east-asian: normal;=
 font-variant-alternates: normal; vertical-align: baseline;">Phase B =E2=80=
=93 </span><span style=3D"font-size: 11pt; font-family: &quot;Courier New&q=
uot;, monospace; color: rgb(0, 0, 0); background-color: transparent; font-v=
ariant-numeric: normal; font-variant-east-asian: normal; font-variant-alter=
nates: normal; vertical-align: baseline;">Disallow spends from quantum vuln=
erable outputs</span></p></span><span style=3D"border-width: 1pt; border-st=
yle: solid; border-color: rgb(0, 0, 0); vertical-align: middle; padding: 5p=
t; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top=
: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 10pt; font-family: &q=
uot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: tr=
ansparent; font-variant-numeric: normal; font-variant-east-asian: normal; f=
ont-variant-alternates: normal; vertical-align: baseline;">At a preset bloc=
k-height, nodes reject transactions that rely on ECDSA/Schnorr keys. </span=
></p></span><span style=3D"border-width: 1pt; border-style: solid; border-c=
olor: rgb(0, 0, 0); vertical-align: middle; padding: 5pt; overflow: hidden;=
"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom=
: 0pt;"><span style=3D"font-size: 10pt; font-family: &quot;Courier New&quot=
;, monospace; color: rgb(0, 0, 0); background-color: transparent; font-styl=
e: italic; font-variant-numeric: normal; font-variant-east-asian: normal; f=
ont-variant-alternates: normal; vertical-align: baseline;">Everyone</span><=
span style=3D"font-size: 10pt; font-family: &quot;Courier New&quot;, monosp=
ace; color: rgb(0, 0, 0); background-color: transparent; font-variant-numer=
ic: normal; font-variant-east-asian: normal; font-variant-alternates: norma=
l; vertical-align: baseline;"> holding or accepting BTC.</span></p></span><=
span style=3D"border-width: 1pt; border-style: solid; border-color: rgb(0, =
0, 0); vertical-align: middle; padding: 5pt; overflow: hidden;"><p dir=3D"l=
tr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span=
 style=3D"font-size: 10pt; font-family: &quot;Courier New&quot;, monospace;=
 color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: =
normal; font-variant-east-asian: normal; font-variant-alternates: normal; v=
ertical-align: baseline;">2 years after Phase A activation.</span></p></spa=
n></span><span style=3D"height: 0pt;"><span style=3D"border-width: 1pt; bor=
der-style: solid; border-color: rgb(0, 0, 0); vertical-align: top; padding:=
 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-=
top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-family:=
 &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color:=
 transparent; font-weight: 700; font-variant-numeric: normal; font-variant-=
east-asian: normal; font-variant-alternates: normal; vertical-align: baseli=
ne;">Phase C =E2=80=93 </span><span style=3D"font-size: 11pt; font-family: =
&quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: =
transparent; font-variant-numeric: normal; font-variant-east-asian: normal;=
 font-variant-alternates: normal; vertical-align: baseline;">Re-enable spen=
ds from quantum vulnerable outputs via ZK Proof</span></p></span><span styl=
e=3D"border-width: 1pt; border-style: solid; border-color: rgb(0, 0, 0); ve=
rtical-align: middle; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=
=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D=
"font-size: 10pt; font-family: &quot;Courier New&quot;, monospace; color: r=
gb(0, 0, 0); background-color: transparent; font-variant-numeric: normal; f=
ont-variant-east-asian: normal; font-variant-alternates: normal; vertical-a=
lign: baseline;">Users with frozen quantum vulnerable funds and a HD wallet=
 seed phrase can construct a quantum safe ZK proof to recover funds.</span>=
</p></span><span style=3D"border-width: 1pt; border-style: solid; border-co=
lor: rgb(0, 0, 0); vertical-align: middle; padding: 5pt; overflow: hidden;"=
><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom:=
 0pt;"><span style=3D"font-size: 10pt; font-family: &quot;Courier New&quot;=
, monospace; color: rgb(0, 0, 0); background-color: transparent; font-varia=
nt-numeric: normal; font-variant-east-asian: normal; font-variant-alternate=
s: normal; vertical-align: baseline;">Users who failed to migrate funds bef=
ore Phase B.</span></p></span><span style=3D"border-width: 1pt; border-styl=
e: solid; border-color: rgb(0, 0, 0); vertical-align: middle; padding: 5pt;=
 overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: =
0pt; margin-bottom: 0pt;"><span style=3D"font-size: 10pt; font-family: &quo=
t;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: tran=
sparent; font-variant-numeric: normal; font-variant-east-asian: normal; fon=
t-variant-alternates: normal; vertical-align: baseline;">TBD pending resear=
ch, demand, and consensus.</span></p></span></span></span></span></div></sp=
an></span><span dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 14pt; m=
argin-bottom: 6pt;"><span style=3D"font-size: 16pt; font-family: &quot;Cour=
ier New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparen=
t; font-weight: 700; font-style: normal; font-variant: normal; text-decorat=
ion: none; vertical-align: baseline; white-space: pre-wrap;">Rationale</spa=
n></span><ul style=3D"margin-top: 0px; margin-bottom: 0px;"><li dir=3D"ltr"=
 style=3D"list-style-type: disc; font-size: 11pt; font-family: &quot;Courie=
r New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent;=
 font-variant-numeric: normal; font-variant-east-asian: normal; font-varian=
t-alternates: normal; vertical-align: baseline; white-space: pre-wrap;"><p =
dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 12=
pt; margin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11=
pt; background-color: transparent; font-variant-numeric: normal; font-varia=
nt-east-asian: normal; font-variant-alternates: normal; vertical-align: bas=
eline;">Even if Bitcoin is not a primary initial target of a cryptographica=
lly relevant quantum computer, widespread knowledge that such a computer ex=
ists and is capable of breaking Bitcoin=E2=80=99s cryptography will damage =
faith in the network . </span></p></li><li dir=3D"ltr" style=3D"list-style-=
type: disc; font-size: 11pt; font-family: &quot;Courier New&quot;, monospac=
e; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric=
: normal; font-variant-east-asian: normal; font-variant-alternates: normal;=
 vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"=
line-height: 1.38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt=
;" role=3D"presentation"><span style=3D"font-size: 11pt; background-color: =
transparent; font-variant-numeric: normal; font-variant-east-asian: normal;=
 font-variant-alternates: normal; vertical-align: baseline;">An attack on B=
itcoin may not be economically motivated - an attacker may be politically o=
r maliciously motivated and may attempt to destroy value and trust in Bitco=
in rather than extract value.  There is no way to know in advance how, when=
, or why an attack may occur.  A defensive position must be taken well in a=
dvance of any attack.  </span></p></li><li dir=3D"ltr" style=3D"list-style-=
type: disc; font-size: 11pt; font-family: &quot;Courier New&quot;, monospac=
e; color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric=
: normal; font-variant-east-asian: normal; font-variant-alternates: normal;=
 vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"=
line-height: 1.38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt=
;" role=3D"presentation"><span style=3D"font-size: 11pt; background-color: =
transparent; font-variant-numeric: normal; font-variant-east-asian: normal;=
 font-variant-alternates: normal; vertical-align: baseline;">Bitcoin=E2=80=
=99s current signatures (ECDSA/Schnorr) will be a tantalizing target: any U=
TXO that has ever exposed its public key on-chain (roughly 25 % of all bitc=
oin) could be stolen by a cryptographically relevant quantum computer.</spa=
n></p></li><li dir=3D"ltr" style=3D"list-style-type: disc; font-size: 11pt;=
 font-family: Arial, sans-serif; color: rgb(0, 0, 0); background-color: tra=
nsparent; font-variant-numeric: normal; font-variant-east-asian: normal; fo=
nt-variant-alternates: normal; vertical-align: baseline; white-space: pre-w=
rap;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margi=
n-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-=
size: 11pt; font-family: &quot;Courier New&quot;, monospace; background-col=
or: transparent; font-weight: 700; font-variant-numeric: normal; font-varia=
nt-east-asian: normal; font-variant-alternates: normal; vertical-align: bas=
eline;">Existing Proposals are Insufficient.</span><span style=3D"font-size=
: 11pt; font-family: &quot;Courier New&quot;, monospace; background-color: =
transparent; font-variant-numeric: normal; font-variant-east-asian: normal;=
 font-variant-alternates: normal; vertical-align: baseline;">  </span></p><=
ol style=3D"margin-top: 0px; margin-bottom: 0px;"><li dir=3D"ltr" style=3D"=
list-style-type: lower-alpha; font-size: 11pt; font-family: &quot;Courier N=
ew&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; fo=
nt-variant-numeric: normal; font-variant-east-asian: normal; font-variant-a=
lternates: normal; vertical-align: baseline; white-space: pre-wrap;"><p dir=
=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 0pt; =
margin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt; =
background-color: transparent; font-variant-numeric: normal; font-variant-e=
ast-asian: normal; font-variant-alternates: normal; vertical-align: baselin=
e;">Any proposal that allows for the quantum theft of =E2=80=9Clost=E2=80=
=9D bitcoin is creating a redistribution dilemma. There are 3 types of prop=
osals:</span></p><ol style=3D"margin-top: 0px; margin-bottom: 0px;"><li dir=
=3D"ltr" style=3D"list-style-type: lower-roman; font-size: 11pt; font-famil=
y: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-colo=
r: transparent; font-variant-numeric: normal; font-variant-east-asian: norm=
al; font-variant-alternates: normal; vertical-align: baseline; white-space:=
 pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify;=
 margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span style=3D=
"font-size: 11pt; background-color: transparent; font-variant-numeric: norm=
al; font-variant-east-asian: normal; font-variant-alternates: normal; verti=
cal-align: baseline;">Allow anyone to steal vulnerable coins, benefitting t=
hose who reach quantum capability earliest.</span></p></li><li dir=3D"ltr" =
style=3D"list-style-type: lower-roman; font-size: 11pt; font-family: &quot;=
Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: transp=
arent; font-variant-numeric: normal; font-variant-east-asian: normal; font-=
variant-alternates: normal; vertical-align: baseline; white-space: pre-wrap=
;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-t=
op: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-siz=
e: 11pt; background-color: transparent; font-variant-numeric: normal; font-=
variant-east-asian: normal; font-variant-alternates: normal; vertical-align=
: baseline;">Allow throttled theft of coins, which leads to RBF battles and=
 ultimately miners subsidizing their revenue from lost coins.</span></p></l=
i><li dir=3D"ltr" style=3D"list-style-type: lower-roman; font-size: 11pt; f=
ont-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); backgr=
ound-color: transparent; font-variant-numeric: normal; font-variant-east-as=
ian: normal; font-variant-alternates: normal; vertical-align: baseline; whi=
te-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align:=
 justify; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span=
 style=3D"font-size: 11pt; background-color: transparent; font-variant-nume=
ric: normal; font-variant-east-asian: normal; font-variant-alternates: norm=
al; vertical-align: baseline;">Allow no one to steal vulnerable coins.</spa=
n></p></li></ol></li></ol></li><li dir=3D"ltr" style=3D"list-style-type: di=
sc; font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color=
: rgb(0, 0, 0); background-color: transparent; font-weight: 700; font-varia=
nt-numeric: normal; font-variant-east-asian: normal; font-variant-alternate=
s: normal; vertical-align: baseline; white-space: pre-wrap;"><p dir=3D"ltr"=
 style=3D"line-height: 1.38; text-align: justify; margin-top: 0pt; margin-b=
ottom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt; backgrou=
nd-color: transparent; font-variant-numeric: normal; font-variant-east-asia=
n: normal; font-variant-alternates: normal; vertical-align: baseline;">Mini=
mizes attack surface</span></p><ol style=3D"margin-top: 0px; margin-bottom:=
 0px;"><li dir=3D"ltr" style=3D"list-style-type: lower-alpha; font-size: 11=
pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); b=
ackground-color: transparent; font-variant-numeric: normal; font-variant-ea=
st-asian: normal; font-variant-alternates: normal; vertical-align: baseline=
; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-a=
lign: justify; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation">=
<span style=3D"font-size: 11pt; background-color: transparent; font-variant=
-numeric: normal; font-variant-east-asian: normal; font-variant-alternates:=
 normal; vertical-align: baseline;">By disallowing new spends to quantum vu=
lnerable script types, we minimize the attack surface with each new UTXO.  =
</span></p></li><li dir=3D"ltr" style=3D"list-style-type: lower-alpha; font=
-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0,=
 0, 0); background-color: transparent; font-variant-numeric: normal; font-v=
ariant-east-asian: normal; font-variant-alternates: normal; vertical-align:=
 baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.3=
8; text-align: justify; margin-top: 0pt; margin-bottom: 0pt;" role=3D"prese=
ntation"><span style=3D"font-size: 11pt; background-color: transparent; fon=
t-variant-numeric: normal; font-variant-east-asian: normal; font-variant-al=
ternates: normal; vertical-align: baseline;">Upgrades to Bitcoin have histo=
rically taken many years; this will hasten and speed up the adoption of new=
 quantum resistant script types. </span></p></li><li dir=3D"ltr" style=3D"l=
ist-style-type: lower-alpha; font-size: 11pt; font-family: &quot;Courier Ne=
w&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; fon=
t-variant-numeric: normal; font-variant-east-asian: normal; font-variant-al=
ternates: normal; vertical-align: baseline; white-space: pre-wrap;"><p dir=
=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 0pt; =
margin-bottom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt; =
background-color: transparent; font-variant-numeric: normal; font-variant-e=
ast-asian: normal; font-variant-alternates: normal; vertical-align: baselin=
e;">With a clear deadline, industry stakeholders will more readily upgrade =
existing infrastructure to ensure continuity of services.  </span></p></li>=
</ol></li><li dir=3D"ltr" style=3D"list-style-type: disc; font-size: 11pt; =
font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); backg=
round-color: transparent; font-weight: 700; font-variant-numeric: normal; f=
ont-variant-east-asian: normal; font-variant-alternates: normal; vertical-a=
lign: baseline; white-space: pre-wrap;"><p dir=3D"ltr" style=3D"line-height=
: 1.38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt;" role=3D"=
presentation"><span style=3D"font-size: 11pt; background-color: transparent=
; font-variant-numeric: normal; font-variant-east-asian: normal; font-varia=
nt-alternates: normal; vertical-align: baseline;">Minimizes loss of access =
to funds </span></p><ol style=3D"margin-top: 0px; margin-bottom: 0px;"><li =
dir=3D"ltr" style=3D"list-style-type: lower-alpha; font-size: 11pt; font-fa=
mily: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-c=
olor: transparent; font-variant-numeric: normal; font-variant-east-asian: n=
ormal; font-variant-alternates: normal; vertical-align: baseline; white-spa=
ce: pre-wrap;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: justi=
fy; margin-top: 0pt; margin-bottom: 12pt;" role=3D"presentation"><span styl=
e=3D"font-size: 11pt; background-color: transparent; font-variant-numeric: =
normal; font-variant-east-asian: normal; font-variant-alternates: normal; v=
ertical-align: baseline;">If there is sufficient demand and research proves=
 possible, submitting a ZK proof of knowledge of a BIP-39 seed phrase corre=
sponding to  a public key hash or script hash would provide a trustless mea=
ns for legacy outputs to be spent in a quantum resistant manner, even after=
 the sunset.  </span></p></li></ol></li></ul><br /><div dir=3D"ltr" style=
=3D"margin-left: 0pt;" align=3D"left"><span style=3D"border: medium; border=
-collapse: collapse;"><span><span width=3D"143"></span><span width=3D"539">=
</span></span><span><span style=3D"height: 27.4463pt;"><span style=3D"borde=
r-width: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-ali=
gn: top; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-heig=
ht: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 1=
1pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); =
background-color: transparent; font-weight: 700; font-variant-numeric: norm=
al; font-variant-east-asian: normal; font-variant-alternates: normal; verti=
cal-align: baseline;">Stakeholder</span></p></span><span style=3D"border-wi=
dth: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align: =
top; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: =
1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt;=
 font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); back=
ground-color: transparent; font-weight: 700; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-alternates: normal; vertical-=
align: baseline;">Incentive to Upgrade</span></p></span></span><span style=
=3D"height: 53.5388pt;"><span style=3D"border-width: 1pt; border-style: sol=
id; border-color: rgb(0, 0, 0); vertical-align: middle; padding: 5pt; overf=
low: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; m=
argin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-family: &quot;Cour=
ier New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparen=
t; font-weight: 700; font-variant-numeric: normal; font-variant-east-asian:=
 normal; font-variant-alternates: normal; vertical-align: baseline;">Miners=
</span></p></span><span style=3D"border-width: 1pt; border-style: solid; bo=
rder-color: rgb(0, 0, 0); vertical-align: top; padding: 5pt; overflow: hidd=
en;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bot=
tom: 0pt;"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&q=
uot;, monospace; color: rgb(0, 0, 0); background-color: transparent; font-v=
ariant-numeric: normal; font-variant-east-asian: normal; font-variant-alter=
nates: normal; vertical-align: baseline;">=E2=80=A2 Larger size PQ signatur=
es along with incentive for users to migrate will create more demand for bl=
ock space and thus higher fees collected by miners.</span></p><p dir=3D"ltr=
" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span s=
tyle=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; c=
olor: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: no=
rmal; font-variant-east-asian: normal; font-variant-alternates: normal; ver=
tical-align: baseline;">=E2=80=A2 Post-Phase B, non-upgraded miners produce=
 invalid blocks.</span></p><p dir=3D"ltr" style=3D"line-height: 1.38; margi=
n-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-famil=
y: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-colo=
r: transparent; font-variant-numeric: normal; font-variant-east-asian: norm=
al; font-variant-alternates: normal; vertical-align: baseline;">=E2=80=A2 A=
 quantum attack on Bitcoin will significantly devalue both their hardware a=
nd Bitcoin as a whole. </span></p></span></span><span style=3D"height: 52pt=
;"><span style=3D"border-width: 1pt; border-style: solid; border-color: rgb=
(0, 0, 0); vertical-align: middle; padding: 5pt; overflow: hidden;"><p dir=
=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;">=
<span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monos=
pace; color: rgb(0, 0, 0); background-color: transparent; font-weight: 700;=
 font-variant-numeric: normal; font-variant-east-asian: normal; font-varian=
t-alternates: normal; vertical-align: baseline;">Institutional Holders</spa=
n></p></span><span style=3D"border-width: 1pt; border-style: solid; border-=
color: rgb(0, 0, 0); vertical-align: top; padding: 5pt; overflow: hidden;">=
<p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: =
0pt;"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;,=
 monospace; color: rgb(0, 0, 0); background-color: transparent; font-varian=
t-numeric: normal; font-variant-east-asian: normal; font-variant-alternates=
: normal; vertical-align: baseline;">=E2=80=A2 Fiduciary duty: failing to a=
ct to prevent a quantum attack on Bitcoin would violate the fiduciary duty =
to shareholders.  </span></p><p dir=3D"ltr" style=3D"line-height: 1.38; mar=
gin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-fam=
ily: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-co=
lor: transparent; font-variant-numeric: normal; font-variant-east-asian: no=
rmal; font-variant-alternates: normal; vertical-align: baseline;">=E2=80=A2=
 Demonstrating Bitcoin=E2=80=99s ability to effectively mitigate emerging t=
hreats will prove Bitcoin to be an investment grade asset.</span></p></span=
></span><span style=3D"height: 52pt;"><span style=3D"border-width: 1pt; bor=
der-style: solid; border-color: rgb(0, 0, 0); vertical-align: middle; paddi=
ng: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; marg=
in-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-fami=
ly: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-col=
or: transparent; font-weight: 700; font-variant-numeric: normal; font-varia=
nt-east-asian: normal; font-variant-alternates: normal; vertical-align: bas=
eline;">Exchanges &amp; Custodians</span></p></span><span style=3D"border-w=
idth: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align:=
 top; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height:=
 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt=
; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); bac=
kground-color: transparent; font-variant-numeric: normal; font-variant-east=
-asian: normal; font-variant-alternates: normal; vertical-align: baseline;"=
>=E2=80=A2 Concentrated risk: a quantum hack could bankrupt them overnight.=
</span></p><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; marg=
in-bottom: 0pt;"><span style=3D"font-size: 11pt; font-family: &quot;Courier=
 New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; =
font-variant-numeric: normal; font-variant-east-asian: normal; font-variant=
-alternates: normal; vertical-align: baseline;">=E2=80=A2 Early migration i=
s cheap relative to potential losses, potential lawsuits over improper cust=
ody and reputational damage.</span></p></span></span><span style=3D"height:=
 52pt;"><span style=3D"border-width: 1pt; border-style: solid; border-color=
: rgb(0, 0, 0); vertical-align: middle; padding: 5pt; overflow: hidden;"><p=
 dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0p=
t;"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, m=
onospace; color: rgb(0, 0, 0); background-color: transparent; font-weight: =
700; font-variant-numeric: normal; font-variant-east-asian: normal; font-va=
riant-alternates: normal; vertical-align: baseline;">Everyday Users</span><=
/p></span><span style=3D"border-width: 1pt; border-style: solid; border-col=
or: rgb(0, 0, 0); vertical-align: top; padding: 5pt; overflow: hidden;"><p =
dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt=
;"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, mo=
nospace; color: rgb(0, 0, 0); background-color: transparent; font-variant-n=
umeric: normal; font-variant-east-asian: normal; font-variant-alternates: n=
ormal; vertical-align: baseline;">=E2=80=A2 Self-sovereign peace of mind.</=
span></p><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin=
-bottom: 0pt;"><span style=3D"font-size: 11pt; font-family: &quot;Courier N=
ew&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; fo=
nt-variant-numeric: normal; font-variant-east-asian: normal; font-variant-a=
lternates: normal; vertical-align: baseline;">=E2=80=A2 Sunset date creates=
 a clear deadline and incentive to improve their security rather than an op=
en-ended =E2=80=9Csome day=E2=80=9D that invites procrastination.</span></p=
></span></span><span style=3D"height: 43.7925pt;"><span style=3D"border-wid=
th: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align: m=
iddle; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height=
: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11p=
t; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); ba=
ckground-color: transparent; font-weight: 700; font-variant-numeric: normal=
; font-variant-east-asian: normal; font-variant-alternates: normal; vertica=
l-align: baseline;">Attackers</span></p></span><span style=3D"border-width:=
 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align: top;=
 padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38=
; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; fon=
t-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); backgrou=
nd-color: transparent; font-variant-numeric: normal; font-variant-east-asia=
n: normal; font-variant-alternates: normal; vertical-align: baseline;">=E2=
=80=A2 Economic incentive diminishes as sunset nears, stolen coins cannot b=
e spent after Q-day.</span></p></span></span></span></span></div><p dir=3D"=
ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 12pt; mar=
gin-bottom: 12pt;"><span style=3D"font-size: 11pt; font-family: &quot;Couri=
er New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent=
; font-weight: 700; font-variant-numeric: normal; font-variant-east-asian: =
normal; font-variant-alternates: normal; vertical-align: baseline;">Key Ins=
ight:</span><span style=3D"font-size: 11pt; font-family: &quot;Courier New&=
quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; font-=
variant-numeric: normal; font-variant-east-asian: normal; font-variant-alte=
rnates: normal; vertical-align: baseline;"> As mentioned earlier, the propo=
sal turns quantum security into a </span><span style=3D"font-size: 11pt; fo=
nt-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); backgro=
und-color: transparent; font-style: italic; font-variant-numeric: normal; f=
ont-variant-east-asian: normal; font-variant-alternates: normal; vertical-a=
lign: baseline;">private incentive to upgrade</span><span style=3D"font-siz=
e: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, =
0); background-color: transparent; font-variant-numeric: normal; font-varia=
nt-east-asian: normal; font-variant-alternates: normal; vertical-align: bas=
eline;">.  </span></p><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top=
: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-family: &q=
uot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: tr=
ansparent; font-variant-numeric: normal; font-variant-east-asian: normal; f=
ont-variant-alternates: normal; vertical-align: baseline;">This is not an o=
ffensive attack, rather, it is defensive: our thesis is that the Bitcoin ec=
osystem wishes to defend itself and its interests against those who would p=
refer to do nothing and allow a malicious actor to destroy both value and t=
rust.  </span></p><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0p=
t; margin-bottom: 0pt;"><span style=3D"background-color: transparent; color=
: rgb(0, 0, 0); font-family: &quot;Courier New&quot;, monospace; font-size:=
 11pt; text-align: center;"><br /></span></p><blockquote style=3D"margin: 0=
px 0px 0px 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: =
1ex;"><span style=3D"background-color: transparent; color: rgb(0, 0, 0); fo=
nt-family: &quot;Courier New&quot;, monospace; font-size: 11pt; text-align:=
 center;">"Lost coins only make everyone else's coins worth slightly more. =
Think of it as a donation to everyone." - Satoshi Nakamoto</span></blockquo=
te><br /><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin=
-bottom: 0pt;"><span style=3D"font-size: 11pt; font-family: &quot;Courier N=
ew&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; fo=
nt-variant-numeric: normal; font-variant-east-asian: normal; font-variant-a=
lternates: normal; vertical-align: baseline;">If true, the corollary is:</s=
pan></p><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-=
bottom: 0pt;"><span style=3D"background-color: transparent; color: rgb(0, 0=
, 0); font-family: &quot;Courier New&quot;, monospace; font-size: 11pt; tex=
t-align: center;"><br /></span></p><blockquote style=3D"margin: 0px 0px 0px=
 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><spa=
n style=3D"background-color: transparent; color: rgb(0, 0, 0); font-family:=
 &quot;Courier New&quot;, monospace; font-size: 11pt; text-align: center;">=
"Quantum recovered coins only make everyone else's coins worth less. Think =
of it as a theft from everyone."</span></blockquote><br /><p dir=3D"ltr" st=
yle=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style=
=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color=
: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: normal=
; font-variant-east-asian: normal; font-variant-alternates: normal; vertica=
l-align: baseline;">The timelines that we are proposing are meant to find t=
he best balance between giving ample ability for account owners to migrate =
while maintaining the integrity of the overall ecosystem to avoid catastrop=
hic attacks.  </span></p><br /><span dir=3D"ltr" style=3D"line-height: 1.38=
; margin-top: 18pt; margin-bottom: 4pt;"><span style=3D"font-size: 17pt; fo=
nt-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); backgro=
und-color: transparent; font-variant-numeric: normal; font-variant-east-asi=
an: normal; font-variant-alternates: normal; vertical-align: baseline;">Bac=
kward Compatibility</span></span><p dir=3D"ltr" style=3D"line-height: 1.38;=
 margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; font=
-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); backgroun=
d-color: transparent; font-variant-numeric: normal; font-variant-east-asian=
: normal; font-variant-alternates: normal; vertical-align: baseline;">As a =
series of soft forks, older nodes will continue to operate without modifica=
tion. Non-upgraded nodes, however, will consider all post-quantum witness p=
rograms as anyone-can-spend scripts. They are strongly encouraged to upgrad=
e in order to fully validate the new programs.</span></p><br /><p dir=3D"lt=
r" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span =
style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; =
color: rgb(0, 0, 0); background-color: transparent; font-variant-numeric: n=
ormal; font-variant-east-asian: normal; font-variant-alternates: normal; ve=
rtical-align: baseline;">Non-upgraded wallets can receive and send bitcoin =
from non-upgraded and upgraded wallets until Phase A. After Phase A, they c=
an no longer receive from any other wallets and can only send to upgraded w=
allets.  After Phase B, both senders and receivers will require upgraded wa=
llets. Phase C would likely require a loosening of consensus rules (a hard =
fork) to allow vulnerable funds recovery via ZK proofs.</span></p></span></=
div>

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