path: root/ec/bca2eeb610d18ea8e0b17637a4da15df8afb4e

Delivery-date: Sun, 20 Jul 2025 15:56:55 -0700
Received: from mail-oa1-f58.google.com ([209.85.160.58])
	by mail.fairlystable.org with esmtps  (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
	(Exim 4.94.2)
	(envelope-from <bitcoindev+bncBCYMD7OS6ECBBLHI6XBQMGQEEKDNKIQ@googlegroups.com>)
	id 1udcxi-0001W2-2v
	for bitcoindev@gnusha.org; Sun, 20 Jul 2025 15:56:55 -0700
Received: by mail-oa1-f58.google.com with SMTP id 586e51a60fabf-2ff9a569aebsf4486843fac.0
        for <bitcoindev@gnusha.org>; Sun, 20 Jul 2025 15:56:53 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=googlegroups.com; s=20230601; t=1753052208; x=1753657008; darn=gnusha.org;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:x-original-sender:mime-version
         :subject:references:in-reply-to:message-id:to:from:date:sender:from
         :to:cc:subject:date:message-id:reply-to;
        bh=y0QBDRSSotBQ6zE1cCFrAFdsd6QxJjgg9W9/ncyP3l0=;
        b=YDLGq8VkLXR45/go7DpFEtE41W2f3GBcnI4PM308qQVaPYoaqjK6iWB6NmFgX5PLsp
         cgO0RfC8sL4d5Uf64BfLhS4cKU0u2hdAiz4UueAUd2hjX/G0VGxTrSLNsvwrlNKzfdJR
         L2XbqtVkvd0hoA58xb3h+kMnU3WSdpylyq7Ps6L/gebHZ7sPTLMWoKiIxIqn7L/3zh5U
         T3XCGxglKPKKEgJaREQobCoBHHCA2rS+UynbToeuIZm7YCH7WfdNp6gFl0qvDTLgYQs2
         0Mhhxu8dyNxzUTM/w0VVZfMuKwcOWrUdmH5Nu/iHyGjq8vBGfc2DZmpPKRUaHXTSvLQy
         2igw==
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20230601; t=1753052208; x=1753657008; darn=gnusha.org;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:x-original-sender:mime-version
         :subject:references:in-reply-to:message-id:to:from:date:from:to:cc
         :subject:date:message-id:reply-to;
        bh=y0QBDRSSotBQ6zE1cCFrAFdsd6QxJjgg9W9/ncyP3l0=;
        b=EDXKgiZ08rZaqVgkaVaBrfSik9UWllYYSflzJmF+MWsNbWSOECJ2GesrTLrdcSQm13
         +QnmnTlQge5FzdDoOJXbEAH9dmv9RTQ+Jhyh+3ftfnLqwrllAPzOWYh4DxlrLr8Wi/vA
         b/wgRyudtURISI0J611BrJuZ1sBM6d7rDwSljG/apCkB/wYcuLclwjGNSla2sg6Mf4kc
         dsoVixcxNxYR1y9Tu25HSHwiHR1i6A0n1/r3AWDv2ppB8W0ecflhoiCh31QAVBBkZ5MV
         Lb4fnWg0KTrHEnubEqQ7HNVeGLVQ/oY4yIu9Dw557W2xUNtxNBk3cbM3K96XnvdSG89s
         0rNw==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20230601; t=1753052208; x=1753657008;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:x-original-sender:mime-version
         :subject:references:in-reply-to:message-id:to:from:date:x-beenthere
         :x-gm-message-state:sender:from:to:cc:subject:date:message-id
         :reply-to;
        bh=y0QBDRSSotBQ6zE1cCFrAFdsd6QxJjgg9W9/ncyP3l0=;
        b=SDM6j/EqmCLZqEQTJeS4JewORcyAxTGD8IfgnGs8l/pjMkDeukKNg25mZTu/8qw1WX
         A1WUQ4K3o1ys2bmLC+AYUeSqbf3/jA9oQU7+XqFOhSaipRCpmwYna2+8rG5vgKP6EfdJ
         Q0wyn9Zk48GxflE3sKNP6WdlX8bbesJi7Lau85jdYMTbvLelWrLNADLU2rRecxq6mHAU
         uq4vwvq6wChaQJKhCcka3AUgHkmy9BTJzpDxgxbxFmXEV9qCwKRXjdXuYoqto4ACvOhJ
         W41u+tUs5foM7nDBtnX4sH5h4e6vWlNxX2ErMUJhqf5aht1Ub546FLPVtWviZ2tFhqeS
         +BfQ==
Sender: bitcoindev@googlegroups.com
X-Forwarded-Encrypted: i=1; AJvYcCVpQjrWegbo+LRhZ0Te0TUojO2VM4I8Ygsar3pLBoxJChTU9Ql9STzmlZ/n67jpOSKQvG5YkibgcCT9@gnusha.org
X-Gm-Message-State: AOJu0Yxc/AHPyXyd78MjGk74baLUe+NFafYinD9s4gI9EasyQWnJrwqt
	u4Fw1n0cRjUEVUupYQYyJy6EiRgmYYR9lZzCdDuCYM8MnuHl+QIqsumA
X-Google-Smtp-Source: AGHT+IH4q9XC1kWgDwMz1hu3NE/FVBGRmh0KUQIwJQ1tDldqFQt0i7e/yiLgNstYoOsO2hqQUPo4jw==
X-Received: by 2002:a05:6870:d390:b0:2da:b440:5b1 with SMTP id 586e51a60fabf-2ffcc17730emr10304613fac.5.1753052207900;
        Sun, 20 Jul 2025 15:56:47 -0700 (PDT)
X-BeenThere: bitcoindev@googlegroups.com; h=AZMbMZcVhFttopjCm7RsrY5No8ZaCrZXPfWswYnC6w6ZzYRmBw==
Received: by 2002:a05:6870:6c02:b0:2ff:8cb6:b720 with SMTP id
 586e51a60fabf-2ffca3d2a0als2760999fac.0.-pod-prod-05-us; Sun, 20 Jul 2025
 15:56:44 -0700 (PDT)
X-Received: by 2002:a05:6808:6c88:b0:40c:fe59:8405 with SMTP id 5614622812f47-41d056571d1mr13980455b6e.31.1753052204068;
        Sun, 20 Jul 2025 15:56:44 -0700 (PDT)
Received: by 2002:a05:690c:9989:b0:711:63b1:720 with SMTP id 00721157ae682-7194e2f0e64ms7b3;
        Sun, 20 Jul 2025 15:54:40 -0700 (PDT)
X-Received: by 2002:a05:690c:f8b:b0:719:671d:255 with SMTP id 00721157ae682-719671d039cmr83766007b3.3.1753052079837;
        Sun, 20 Jul 2025 15:54:39 -0700 (PDT)
Date: Sun, 20 Jul 2025 15:54:39 -0700 (PDT)
From: Boris Nagaev <bnagaev@gmail.com>
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Message-Id: <cfb00fb3-1eeb-40c5-acc3-50d1919d7dben@googlegroups.com>
In-Reply-To: <CADL_X_fpv-aXBxX+eJ_EVTirkAJGyPRUNqOCYdz5um8zu6ma5Q@mail.gmail.com>
References: <CADL_X_fpv-aXBxX+eJ_EVTirkAJGyPRUNqOCYdz5um8zu6ma5Q@mail.gmail.com>
Subject: [bitcoindev] Re: A Post Quantum Migration Proposal
MIME-Version: 1.0
Content-Type: multipart/mixed; 
	boundary="----=_Part_267154_1311451799.1753052079455"
X-Original-Sender: bnagaev@gmail.com
Precedence: list
Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com
List-ID: <bitcoindev.googlegroups.com>
X-Google-Group-Id: 786775582512
List-Post: <https://groups.google.com/group/bitcoindev/post>, <mailto:bitcoindev@googlegroups.com>
List-Help: <https://groups.google.com/support/>, <mailto:bitcoindev+help@googlegroups.com>
List-Archive: <https://groups.google.com/group/bitcoindev
List-Subscribe: <https://groups.google.com/group/bitcoindev/subscribe>, <mailto:bitcoindev+subscribe@googlegroups.com>
List-Unsubscribe: <mailto:googlegroups-manage+786775582512+unsubscribe@googlegroups.com>,
 <https://groups.google.com/group/bitcoindev/subscribe>
X-Spam-Score: -0.5 (/)

------=_Part_267154_1311451799.1753052079455
Content-Type: multipart/alternative; 
	boundary="----=_Part_267155_1449090592.1753052079455"

------=_Part_267155_1449090592.1753052079455
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Hi Jameson, hi all!

I have a couple of ideas on how to preserve more funds during any kind of=
=20
fork that constrains or blocks currently used spending scenarios. This=20
applies to both freezing and commit/reveal schemes; the latter may result=
=20
in lost funds if the public key is leaked. I realized that this also=20
applies to the commit/reveal scheme I proposed in another thread [1].

The idea is to *roll out such forks incrementally across the UTXO set*.=20
Instead of freezing or constraining all UTXOs at once, we split the UTXO=20
set into 256 groups deterministically (for example, by looking at the first=
=20
byte of the TXID) and apply the constraints over 256 days, processing one=
=20
group per day. Procrastinators will learn what is happening through word of=
=20
mouth, act to save their funds, and only a small percentage of coin owners=
=20
will be harmed.

Another approach is to *provide a temporary opt-out option*. If someone=20
finds themselves blocked, they would still have a limited time to take an=
=20
action, without requiring any extra knowledge, to get unblocked. This would=
=20
help raise awareness. After being temporarily blocked and recovering their=
=20
funds through the opt-out mechanism, the person would understand that they=
=20
need to take further steps with their remaining coins to avoid being=20
permanently blocked once the opt-out period ends. The action to unblock the=
=20
funds could be as simple as sending a transaction with OP_RETURN "opt-out=
=20
<txid>", which would enable the old acceptance rules for the transaction=20
with that txid for a period of 2016 blocks.


[1] https://groups.google.com/g/bitcoindev/c/uUK6py0Yjq0/m/57bQJ3VSCQAJ
In that scheme if the pubkey is leaked, anyone can post a valid commitment=
=20
with a random TXID blocking the coin forever.

Best,
Boris

On Saturday, July 12, 2025 at 9:46:09=E2=80=AFPM UTC-3 Jameson Lopp 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 rema=
in=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 mus=
t=20
   be 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.

--=20
You received this message because you are subscribed to the Google Groups "=
Bitcoin Development Mailing List" group.
To unsubscribe from this group and stop receiving emails from it, send an e=
mail to bitcoindev+unsubscribe@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/=
cfb00fb3-1eeb-40c5-acc3-50d1919d7dben%40googlegroups.com.

------=_Part_267155_1449090592.1753052079455
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Hi Jameson, hi all!<br /><br />I have a couple of ideas on how to preserve =
more funds during any kind of fork that constrains or blocks currently used=
 spending scenarios. This applies to both freezing and commit/reveal scheme=
s; the latter may result in lost funds if the public key is leaked. I reali=
zed that this also applies to the commit/reveal scheme I proposed in anothe=
r thread [1].<br /><br /><div>The idea is to <b>roll out such forks increme=
ntally across the UTXO set</b>. Instead of freezing or constraining all UTX=
Os at once, we split the UTXO set into 256 groups deterministically (for ex=
ample, by looking at the first byte of the TXID) and apply the constraints =
over 256 days, processing one group per day. Procrastinators will learn wha=
t is happening through word of mouth, act to save their funds, and only a s=
mall percentage of coin owners will be harmed.</div><div><br /></div><div>A=
nother approach is to <b>provide a temporary opt-out option</b>. If someone=
 finds themselves blocked, they would still have a limited time to take an =
action, without requiring any extra knowledge, to get unblocked. This would=
 help raise awareness. After being temporarily blocked and recovering their=
 funds through the opt-out mechanism, the person would understand that they=
 need to take further steps with their remaining coins to avoid being perma=
nently blocked once the opt-out period ends.=C2=A0The action to unblock the=
 funds could be as simple as sending a transaction with OP_RETURN "opt-out =
&lt;txid&gt;", which would enable the old acceptance rules for the transact=
ion with that txid for a period of 2016 blocks.</div><div><br /></div><div>=
<br /></div><div>[1]=C2=A0https://groups.google.com/g/bitcoindev/c/uUK6py0Y=
jq0/m/57bQJ3VSCQAJ</div><div>In that scheme if the pubkey is leaked, anyone=
 can post a valid commitment with a random TXID blocking the coin forever.<=
/div><div><br /></div>Best,<br /><div>Boris</div><div><br /></div><div><div=
 dir=3D"auto">On Saturday, July 12, 2025 at 9:46:09=E2=80=AFPM UTC-3 Jameso=
n Lopp wrote:<br /></div><blockquote style=3D"margin: 0px 0px 0px 0.8ex; bo=
rder-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div dir=3D"lt=
r"><span><p dir=3D"ltr" style=3D"line-height: 1.44; background-color: rgb(2=
55, 255, 255); margin-top: 12pt; margin-bottom: 0pt; padding: 0pt 0pt 12pt;=
"><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;">Building upon my earlier essa=
y </span><a href=3D"https://groups.google.com/g/bitcoindev/c/uUK6py0Yjq0/m/=
6peEaa90AQAJ" style=3D"text-decoration: none;" target=3D"_blank" rel=3D"nof=
ollow"><span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;=
, monospace; color: rgb(17, 85, 204); background-color: transparent; font-w=
eight: 400; font-style: normal; font-variant: normal; text-decoration: unde=
rline; vertical-align: baseline; white-space: pre-wrap;">against allowing q=
uantum recovery of bitcoin</span></a><span style=3D"font-size: 11pt; font-f=
amily: &quot;Courier New&quot;, monospace; color: rgb(34, 34, 34); backgrou=
nd-color: transparent; font-weight: 400; font-style: normal; font-variant: =
normal; text-decoration: none; vertical-align: baseline; white-space: pre-w=
rap;"> I wish to formalize a proposal after several months of discussions.<=
/span></p><p dir=3D"ltr" style=3D"line-height: 1.44; background-color: rgb(=
255, 255, 255); margin-top: 0pt; margin-bottom: 0pt; padding: 0pt 0pt 12pt;=
"><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;">This proposal does not delve =
into the multitude of issues regarding post quantum cryptography and trade-=
offs of different schemes, but rather is meant to specifically address the =
issues of incentivizing adoption and migration of funds </span><span style=
=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color=
: rgb(34, 34, 34); background-color: transparent; font-weight: 400; font-va=
riant: normal; text-decoration: none; vertical-align: baseline; white-space=
: pre-wrap;"><i>after</i></span><span style=3D"font-size: 11pt; font-family=
: &quot;Courier New&quot;, monospace; color: rgb(34, 34, 34); background-co=
lor: transparent; font-weight: 400; font-style: normal; font-variant: norma=
l; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"=
> consensus is established that it is prudent to do so.</span></p><p dir=3D=
"ltr" style=3D"line-height: 1.44; background-color: rgb(255, 255, 255); mar=
gin-top: 0pt; margin-bottom: 12pt;"><span style=3D"font-size: 11pt; font-fa=
mily: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-c=
olor: transparent; font-weight: 400; font-style: normal; font-variant: norm=
al; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;=
">As such, this proposal requires P2QRH as described in BIP-360 or potentia=
l future proposals.</span></p><span dir=3D"ltr" style=3D"line-height: 1.38;=
 margin-top: 18pt; margin-bottom: 4pt;"><span style=3D"font-size: 17pt; 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;">Abst=
ract</span></span><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 12=
pt; margin-bottom: 12pt;"><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;">This proposal foll=
ows the implementation of post-quantum (PQ) output type (P2QRH) and introdu=
ces a pre-announced sunset of legacy ECDSA/Schnorr signatures. It turns qua=
ntum security into a </span><span style=3D"font-size: 11pt; font-family: &q=
uot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: tr=
ansparent; font-style: italic; font-variant-numeric: normal; font-variant-e=
ast-asian: normal; font-variant-alternates: normal; vertical-align: baselin=
e;">private incentive</span><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;">: fail to upgrad=
e and you will certainly lose access to your funds, creating a certainty wh=
ere none previously existed.=C2=A0</span></p><ul style=3D"margin-top: 0px; =
margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: disc; font-s=
ize: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0=
, 0); background-color: transparent; font-variant-numeric: normal; font-var=
iant-east-asian: normal; font-variant-alternates: normal; vertical-align: b=
aseline; white-space: pre;"><p dir=3D"ltr" style=3D"line-height: 1.38; marg=
in-top: 0pt; margin-bottom: 0pt;" 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: baseline;">Phase A:</span><span style=3D"font-size:=
 11pt; background-color: transparent; font-variant-numeric: normal; font-va=
riant-east-asian: normal; font-variant-alternates: normal; vertical-align: =
baseline;"> Disallows sending of any funds to quantum-vulnerable addresses,=
 hastening the adoption of P2QRH address types.</span></p></li><li dir=3D"l=
tr" style=3D"list-style-type: disc; font-size: 11pt; font-family: &quot;Cou=
rier New&quot;, monospace; color: rgb(0, 0, 0); background-color: transpare=
nt; font-variant-numeric: normal; font-variant-east-asian: normal; font-var=
iant-alternates: normal; vertical-align: baseline; white-space: pre;"><p di=
r=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: tr=
ansparent; font-weight: 700; font-variant-numeric: normal; font-variant-eas=
t-asian: normal; font-variant-alternates: normal; vertical-align: baseline;=
">Phase B:</span><span style=3D"font-size: 11pt; background-color: transpar=
ent; font-variant-numeric: normal; font-variant-east-asian: normal; font-va=
riant-alternates: normal; vertical-align: baseline;"> Renders ECDSA/Schnorr=
 spends invalid, preventing all spending of funds in quantum-vulnerable UTX=
Os. This is triggered by a well-publicized flag-day roughly five years afte=
r activation.</span></p></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); background-color: transparent; font-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-alternates: normal; vertical-=
align: baseline; white-space: pre;"><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: normal; font-variant-east-asian: normal; font-variant-alte=
rnates: normal; vertical-align: baseline;">Phase C (optional):</span><span =
style=3D"font-size: 11pt; background-color: transparent; font-variant-numer=
ic: normal; font-variant-east-asian: normal; font-variant-alternates: norma=
l; vertical-align: baseline;"> Pending further research and demand, a separ=
ate BIP proposing a fork to allow recovery of legacy UTXOs through ZK proof=
 of possession of BIP-39 seed phrase.=C2=A0=C2=A0</span></p></li></ul><span=
 dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 1=
4pt; margin-bottom: 6pt;"><span style=3D"font-size: 16pt; 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;">Motivation</span><=
/span><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margi=
n-top: 12pt; margin-bottom: 12pt;"><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;">We seek t=
o secure the value of the UTXO set</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-weight: 700; font-variant-numeric: normal; fon=
t-variant-east-asian: normal; font-variant-alternates: normal; vertical-ali=
gn: baseline;"> </span><span style=3D"font-size: 11pt; font-family: &quot;C=
ourier New&quot;, monospace; color: rgb(0, 0, 0); background-color: transpa=
rent; font-variant-numeric: normal; font-variant-east-asian: normal; font-v=
ariant-alternates: normal; vertical-align: baseline;">and minimize incentiv=
es for quantum attacks. This proposal is radically different from any in Bi=
tcoin=E2=80=99s history just as the threat posed by quantum computing is ra=
dically different from any other threat in Bitcoin=E2=80=99s history.=C2=A0=
 Never before has Bitcoin faced an existential threat to its cryptographic =
primitives. A successful quantum attack on Bitcoin would result in signific=
ant economic disruption and damage across the entire ecosystem. Beyond its =
impact on price, the ability of miners to provide network security may be s=
ignificantly impacted.=C2=A0=C2=A0</span></p><ul style=3D"margin-top: 0px; =
margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: disc; font-s=
ize: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0=
, 0); background-color: transparent; font-variant-numeric: normal; font-var=
iant-east-asian: normal; font-variant-alternates: normal; vertical-align: b=
aseline; white-space: pre;"><p dir=3D"ltr" style=3D"line-height: 1.38; marg=
in-top: 12pt; margin-bottom: 0pt;" role=3D"presentation"><span style=3D"fon=
t-size: 11pt; background-color: transparent; font-weight: 700; font-variant=
-numeric: normal; font-variant-east-asian: normal; font-variant-alternates:=
 normal; vertical-align: baseline;">Accelerating quantum progress.</span><s=
pan style=3D"font-size: 11pt; background-color: transparent; font-variant-n=
umeric: normal; font-variant-east-asian: normal; font-variant-alternates: n=
ormal; vertical-align: baseline;">=C2=A0</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-variant-numeric: normal; =
font-variant-east-asian: normal; font-variant-alternates: normal; vertical-=
align: baseline; white-space: pre;"><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: n=
ormal; font-variant-east-asian: normal; font-variant-alternates: normal; ve=
rtical-align: baseline;">NIST ratified three production-grade PQ signature =
schemes in 2024; academic road-maps now estimate a cryptographically-releva=
nt quantum computer as early as 2027-2030. [</span><a href=3D"https://www.m=
ckinsey.com/~/media/mckinsey/business%20functions/mckinsey%20digital/our%20=
insights/the%20year%20of%20quantum%20from%20concept%20to%20reality%20in%202=
025/quantum-monitor-2025.pdf?shouldIndex=3Dfalse" style=3D"text-decoration-=
line: none;" target=3D"_blank" rel=3D"nofollow"><span style=3D"font-size: 1=
1pt; background-color: transparent; font-variant-numeric: normal; font-vari=
ant-east-asian: normal; font-variant-alternates: normal; text-decoration-li=
ne: underline; vertical-align: baseline;">McKinsey</span></a><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;">]</span></p></li></ul></li><li dir=3D"ltr" style=3D"l=
ist-style-type: disc; font-size: 11pt; font-family: &quot;Courier New&quot;=
, monospace; color: rgb(0, 0, 0); background-color: transparent; font-weigh=
t: 700; font-variant-numeric: normal; font-variant-east-asian: normal; font=
-variant-alternates: normal; vertical-align: baseline; white-space: pre;"><=
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: 1=
1pt; background-color: transparent; font-variant-numeric: normal; font-vari=
ant-east-asian: normal; font-variant-alternates: normal; vertical-align: ba=
seline;">Quantum algorithms are rapidly improving</span></p><ul style=3D"ma=
rgin-top: 0px; margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-typ=
e: circle; 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; white-space: pre;"><p dir=3D"ltr" style=3D"line-h=
eight: 1.38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt;" rol=
e=3D"presentation"><span style=3D"font-size: 11pt; background-color: transp=
arent; font-variant-numeric: normal; font-variant-east-asian: normal; font-=
variant-alternates: normal; vertical-align: baseline;">The safety envelope =
is shrinking by dramatic increases in algorithms even if the pace of hardwa=
re improvements is slower. Algorithms are <a href=3D"https://security.googl=
eblog.com/2025/05/tracking-cost-of-quantum-factori.html" target=3D"_blank" =
rel=3D"nofollow">improving up to 20X</a>, lowering the theoretical 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); background-color=
: transparent; font-variant-numeric: normal; font-variant-east-asian: norma=
l; font-variant-alternates: normal; vertical-align: baseline; white-space: =
pre;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bo=
ttom: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt; backgroun=
d-color: transparent; font-weight: 700; font-variant-numeric: normal; font-=
variant-east-asian: normal; font-variant-alternates: normal; vertical-align=
: baseline;">Bitcoin=E2=80=99s exposed public keys.</span><span style=3D"fo=
nt-size: 11pt; background-color: transparent; font-variant-numeric: normal;=
 font-variant-east-asian: normal; font-variant-alternates: normal; vertical=
-align: baseline;">=C2=A0</span></p><ul style=3D"margin-top: 0px; margin-bo=
ttom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: circle; 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;"><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-var=
iant-east-asian: normal; font-variant-alternates: normal; vertical-align: b=
aseline;">Roughly 25% of all bitcoin have revealed a public key on-chain; t=
hose UTXOs could be stolen with sufficient quantum power.=C2=A0=C2=A0</span=
></p></li></ul></li><li dir=3D"ltr" style=3D"list-style-type: disc; 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;"><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-weight=
: 700; font-variant-numeric: normal; font-variant-east-asian: normal; font-=
variant-alternates: normal; vertical-align: baseline;">We may not know the =
attack is underway.=C2=A0</span></p><ul style=3D"margin-top: 0px; margin-bo=
ttom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: circle; 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;"><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;">Quantum attackers could compute the private =
key for known public keys then transfer all funds weeks or months later, in=
 a covert bleed to not alert chain watchers. Q-Day may be only known much l=
ater if the attack withholds broadcasting transactions in order to postpone=
 revealing their capabilities.</span></p></li></ul></li><li dir=3D"ltr" sty=
le=3D"list-style-type: disc; font-size: 11pt; font-family: &quot;Courier Ne=
w&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; fon=
t-weight: 700; font-variant-numeric: normal; font-variant-east-asian: norma=
l; font-variant-alternates: normal; vertical-align: baseline; white-space: =
pre;"><p dir=3D"ltr" style=3D"line-height: 1.38; 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;">Priva=
te keys become public.=C2=A0</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: no=
rmal; font-variant-east-asian: normal; font-variant-alternates: normal; ver=
tical-align: baseline; white-space: pre;"><p dir=3D"ltr" style=3D"line-heig=
ht: 1.38; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span=
 style=3D"font-size: 11pt; background-color: transparent; font-weight: 400;=
 font-variant-numeric: normal; font-variant-east-asian: normal; font-varian=
t-alternates: normal; vertical-align: baseline;">Assuming that quantum comp=
uters are able to maintain their current trajectories and overcome existing=
 engineering obstacles, there is a near certain chance that all P2PK (and o=
ther outputs with exposed pubkeys) private keys will be found and used to s=
teal the funds.</span></p></li></ul></li><li dir=3D"ltr" style=3D"list-styl=
e-type: disc; font-size: 11pt; font-family: &quot;Courier New&quot;, monosp=
ace; 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;"><p dir=3D=
"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" rol=
e=3D"presentation"><span style=3D"font-size: 11pt; background-color: transp=
arent; font-variant-numeric: normal; font-variant-east-asian: normal; font-=
variant-alternates: normal; vertical-align: baseline;">Impossible to know m=
otivations.=C2=A0</span></p><ul style=3D"margin-top: 0px; margin-bottom: 0p=
x;"><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); backgroun=
d-color: transparent; font-weight: 700; font-variant-numeric: normal; font-=
variant-east-asian: normal; font-variant-alternates: normal; vertical-align=
: baseline; white-space: pre;"><p dir=3D"ltr" style=3D"line-height: 1.38; m=
argin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span style=3D"f=
ont-size: 11pt; background-color: transparent; font-weight: 400; font-varia=
nt-numeric: normal; font-variant-east-asian: normal; font-variant-alternate=
s: normal; vertical-align: baseline;">Prior to a quantum attack, it is impo=
ssible to know the motivations of the attacker.=C2=A0 An economically motiv=
ated attacker will try to remain undetected for as long as possible, while =
a malicious attacker will attempt to destroy as much value as possible.=C2=
=A0=C2=A0</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; 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; white-space: pre;"><p dir=3D"ltr" style=3D"line-heig=
ht: 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-numeric: normal; font-variant-east-asian: normal; font-varian=
t-alternates: normal; vertical-align: baseline;">Upgrade inertia.</span><sp=
an style=3D"font-size: 11pt; background-color: transparent; font-variant-nu=
meric: normal; font-variant-east-asian: normal; font-variant-alternates: no=
rmal; vertical-align: baseline;">=C2=A0</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: 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; white-space: pre;"><p dir=3D"ltr" style=3D"line-height: 1.3=
8; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span style=
=3D"font-size: 11pt; background-color: transparent; font-variant-numeric: n=
ormal; font-variant-east-asian: normal; font-variant-alternates: normal; ve=
rtical-align: baseline;">Coordinating wallets, exchanges, miners and custod=
ians historically takes years.</span></p></li><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-varian=
t-numeric: normal; font-variant-east-asian: normal; font-variant-alternates=
: normal; vertical-align: baseline; white-space: pre;"><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-col=
or: transparent; font-variant-numeric: normal; font-variant-east-asian: nor=
mal; font-variant-alternates: normal; vertical-align: baseline;">The longer=
 we postpone migration, the harder it becomes to coordinate wallets, exchan=
ges, miners, and custodians. A clear, time-boxed pathway is the only credib=
le defense.</span></p></li><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: normal; =
font-variant-east-asian: normal; font-variant-alternates: normal; vertical-=
align: baseline; white-space: pre;"><p dir=3D"ltr" style=3D"line-height: 1.=
38; text-align: justify; margin-top: 0pt; margin-bottom: 12pt;" role=3D"pre=
sentation"><span style=3D"font-size: 11pt; background-color: transparent; f=
ont-variant-numeric: normal; font-variant-east-asian: normal; font-variant-=
alternates: normal; vertical-align: baseline;">Coordinating distributed gro=
ups is more prone to delay, even if everyone has similar motivations. Histo=
rically, 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" styl=
e=3D"line-height: 1.38; text-align: justify; margin-top: 14pt; margin-botto=
m: 6pt;"><span style=3D"font-size: 16pt; 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;">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; 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;"><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 N=
ew&quot;, monospace; background-color: transparent; font-weight: 700; font-=
variant-numeric: normal; font-variant-east-asian: normal; font-variant-alte=
rnates: normal; vertical-align: baseline;">Resilience:</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;"> Bit=
coin protocol remains secure for the foreseeable future without waiting for=
 a last-minute emergency.</span></p></li><li dir=3D"ltr" style=3D"list-styl=
e-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-alternates: normal; vertical-align=
: baseline; white-space: pre;"><p dir=3D"ltr" style=3D"line-height: 1.38; t=
ext-align: justify; margin-top: 0pt; margin-bottom: 0pt;" 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;">Certainty</span><span style=3D"font-size: =
11pt; font-family: &quot;Courier New&quot;, monospace; background-color: tr=
ansparent; font-variant-numeric: normal; font-variant-east-asian: normal; f=
ont-variant-alternates: normal; vertical-align: baseline;">: Bitcoin users =
and stakeholders gain certainty that a plan is both in place and being impl=
emented to effectively deal with the threat of quantum theft of bitcoin.=C2=
=A0=C2=A0</span></p></li><li dir=3D"ltr" style=3D"list-style-type: disc; fo=
nt-size: 11pt; font-family: Arial, sans-serif; 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; whit=
e-space: pre;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: justi=
fy; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span style=
=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; 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;">Clarity:</span><span style=3D"font-size: 11pt; font-family=
: &quot;Courier New&quot;, monospace; background-color: transparent; font-v=
ariant-numeric: normal; font-variant-east-asian: normal; font-variant-alter=
nates: normal; vertical-align: baseline;"> A single, publicized timeline al=
igns 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: transpar=
ent; font-variant-numeric: normal; font-variant-east-asian: normal; font-va=
riant-alternates: normal; vertical-align: baseline; white-space: pre;"><p d=
ir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 0pt=
; margin-bottom: 12pt;" role=3D"presentation"><span style=3D"font-size: 11p=
t; font-family: &quot;Courier New&quot;, monospace; background-color: trans=
parent; font-weight: 700; font-variant-numeric: normal; font-variant-east-a=
sian: normal; font-variant-alternates: normal; vertical-align: baseline;">S=
upply Discipline:</span><span style=3D"font-size: 11pt; font-family: &quot;=
Courier New&quot;, monospace; background-color: transparent; font-variant-n=
umeric: normal; font-variant-east-asian: normal; font-variant-alternates: n=
ormal; vertical-align: baseline;"> Abandoned keys that never migrate become=
 unspendable, reducing supply, <a href=3D"https://bitcointalk.org/index.php=
?topic=3D198.msg1647#msg1647" target=3D"_blank" rel=3D"nofollow">as Satoshi=
 described</a></span><span style=3D"font-size: 11pt; font-family: &quot;Cou=
rier New&quot;, monospace; background-color: transparent; font-variant-nume=
ric: normal; font-variant-east-asian: normal; font-variant-alternates: norm=
al; vertical-align: baseline;">.=C2=A0=C2=A0</span></p></li></ul><span dir=
=3D"ltr" style=3D"line-height: 1.38; text-align: justify; margin-top: 12pt;=
 margin-bottom: 12pt;"><span style=3D"font-size: 16pt; font-family: &quot;C=
ourier New&quot;, monospace; color: rgb(0, 0, 0); background-color: transpa=
rent; font-variant-numeric: normal; font-variant-east-asian: normal; font-v=
ariant-alternates: normal; vertical-align: baseline;">Specification</span><=
/span><span dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; ma=
rgin-top: 12pt; margin-bottom: 12pt;"><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"></spa=
n><span width=3D"224"></span><span width=3D"137"></span><span width=3D"130"=
></span></span><span><span style=3D"height: 0pt;"><span style=3D"border-wid=
th: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align: t=
op; 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;, 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;">Phase</span></p></span><span style=3D=
"border-width: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertic=
al-align: top; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"lin=
e-height: 1.38; text-align: center; margin-top: 0pt; margin-bottom: 0pt;"><=
span style=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monosp=
ace; 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;">What Happens</span></p></sp=
an><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; text-align: center; margin-top: 0pt; margi=
n-bottom: 0pt;"><span style=3D"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;">Who Must A=
ct</span></p></span><span style=3D"border-width: 1pt; border-style: solid; =
border-color: rgb(0, 0, 0); vertical-align: top; padding: 5pt; overflow: hi=
dden;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: center; 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-weight: 700; font-variant-numeric: normal; font-varian=
t-east-asian: normal; font-variant-alternates: normal; vertical-align: base=
line;">Time Horizon</span></p></span></span><span style=3D"height: 0pt;"><s=
pan 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 sty=
le=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; col=
or: rgb(0, 0, 0); background-color: transparent; font-weight: 700; font-var=
iant-numeric: normal; font-variant-east-asian: normal; font-variant-alterna=
tes: normal; vertical-align: baseline;">Phase A - </span><span style=3D"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;">Disallow spends to legacy script types</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"ltr" s=
tyle=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span styl=
e=3D"font-size: 10pt; font-family: &quot;Courier New&quot;, monospace; 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;">Permitted sends are from legacy scripts to P2QRH scrip=
ts</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"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margi=
n-bottom: 0pt;"><span style=3D"font-size: 10pt; font-family: &quot;Courier =
New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent; f=
ont-style: italic; font-variant-numeric: normal; font-variant-east-asian: n=
ormal; font-variant-alternates: normal; vertical-align: baseline;">Everyone=
</span><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;"> 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"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;, 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;">3 years after BIP-360 implementation</spa=
n></p></span></span><span style=3D"height: 0pt;"><span style=3D"border-widt=
h: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align: to=
p; 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; f=
ont-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); backgr=
ound-color: transparent; font-weight: 700; font-variant-numeric: normal; fo=
nt-variant-east-asian: normal; font-variant-alternates: normal; vertical-al=
ign: baseline;">Phase B =E2=80=93 </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-variant-numeric: normal; font-variant-east-asi=
an: normal; font-variant-alternates: normal; vertical-align: baseline;">Dis=
allow spends from quantum vulnerable outputs</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-variant-numeric: normal; f=
ont-variant-east-asian: normal; font-variant-alternates: normal; vertical-a=
lign: baseline;">At a preset block-height, nodes reject transactions that r=
ely on ECDSA/Schnorr keys.=C2=A0</span></p></span><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: 10p=
t; font-family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); ba=
ckground-color: transparent; font-style: italic; font-variant-numeric: norm=
al; font-variant-east-asian: normal; font-variant-alternates: normal; verti=
cal-align: baseline;">Everyone</span><span style=3D"font-size: 10pt; 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;"> holdin=
g or accepting BTC.</span></p></span><span style=3D"border-width: 1pt; bord=
er-style: solid; border-color: rgb(0, 0, 0); vertical-align: middle; paddin=
g: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; margi=
n-top: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 10pt; 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;">2 years aft=
er Phase A activation.</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; padding: 5pt; overflow: hidden;"><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-weight: 700; font-=
variant-numeric: normal; font-variant-east-asian: normal; font-variant-alte=
rnates: normal; vertical-align: baseline;">Phase C =E2=80=93 </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;">Re-enable spends from quantum vulnerable outputs vi=
a ZK Proof</span></p></span><span style=3D"border-width: 1pt; border-style:=
 solid; border-color: rgb(0, 0, 0); vertical-align: middle; padding: 5pt; o=
verflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0p=
t; margin-bottom: 0pt;"><span style=3D"font-size: 10pt; 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;">Users with frozen qu=
antum 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-widt=
h: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align: mi=
ddle; 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); bac=
kground-color: transparent; font-variant-numeric: normal; font-variant-east=
-asian: normal; font-variant-alternates: normal; vertical-align: baseline;"=
>Users who failed to migrate funds before Phase B.</span></p></span><span s=
tyle=3D"border-width: 1pt; border-style: solid; border-color: rgb(0, 0, 0);=
 vertical-align: middle; padding: 5pt; overflow: hidden;"><p dir=3D"ltr" st=
yle=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; vertica=
l-align: baseline;">TBD pending research, demand, and consensus.</span></p>=
</span></span></span></span></div></span></span><span dir=3D"ltr" style=3D"=
line-height: 1.38; margin-top: 14pt; margin-bottom: 6pt;"><span style=3D"fo=
nt-size: 16pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(=
0, 0, 0); background-color: transparent; font-weight: 700; font-style: norm=
al; font-variant: normal; text-decoration: none; vertical-align: baseline; =
white-space: pre-wrap;">Rationale</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: &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;"><p dir=3D"ltr" style=3D"line-height: 1.38; te=
xt-align: justify; margin-top: 12pt; margin-bottom: 0pt;" role=3D"presentat=
ion"><span style=3D"font-size: 11pt; background-color: transparent; font-va=
riant-numeric: normal; font-variant-east-asian: normal; font-variant-altern=
ates: normal; vertical-align: baseline;">Even if Bitcoin is not a primary i=
nitial target of a cryptographically relevant quantum computer, widespread =
knowledge that such a computer exists and is capable of breaking Bitcoin=E2=
=80=99s cryptography will damage faith in the network .=C2=A0</span></p></l=
i><li dir=3D"ltr" style=3D"list-style-type: disc; 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; white-spac=
e: pre;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: justify; ma=
rgin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><span style=3D"fo=
nt-size: 11pt; background-color: transparent; font-variant-numeric: normal;=
 font-variant-east-asian: normal; font-variant-alternates: normal; vertical=
-align: baseline;">An attack on Bitcoin may not be economically motivated -=
 an attacker may be politically or maliciously motivated and may attempt to=
 destroy value and trust in Bitcoin rather than extract value.=C2=A0 There =
is no way to know in advance how, when, or why an attack may occur.=C2=A0 A=
 defensive position must be taken well in advance of any attack.=C2=A0=C2=
=A0</span></p></li><li dir=3D"ltr" style=3D"list-style-type: disc; 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; white-space: pre;"><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;">Bitcoin=E2=80=99s current signatures (E=
CDSA/Schnorr) will be a tantalizing target: any UTXO that has ever exposed =
its public key on-chain (roughly 25 % of all bitcoin) could be stolen by a =
cryptographically relevant quantum computer.</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-num=
eric: normal; font-variant-east-asian: normal; font-variant-alternates: nor=
mal; vertical-align: baseline; white-space: pre;"><p dir=3D"ltr" style=3D"l=
ine-height: 1.38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt;=
" role=3D"presentation"><span style=3D"font-size: 11pt; font-family: &quot;=
Courier New&quot;, monospace; background-color: transparent; font-weight: 7=
00; font-variant-numeric: normal; font-variant-east-asian: normal; font-var=
iant-alternates: normal; vertical-align: baseline;">Existing Proposals are =
Insufficient.</span><span style=3D"font-size: 11pt; font-family: &quot;Cour=
ier New&quot;, monospace; background-color: transparent; font-variant-numer=
ic: normal; font-variant-east-asian: normal; font-variant-alternates: norma=
l; vertical-align: baseline;">=C2=A0=C2=A0</span></p><ol style=3D"margin-to=
p: 0px; margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-style-type: lowe=
r-alpha; 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;"><p dir=3D"ltr" style=3D"line-hei=
ght: 1.38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt;" role=
=3D"presentation"><span style=3D"font-size: 11pt; background-color: transpa=
rent; font-variant-numeric: normal; font-variant-east-asian: normal; font-v=
ariant-alternates: normal; vertical-align: baseline;">Any proposal that all=
ows for the quantum theft of =E2=80=9Clost=E2=80=9D bitcoin is creating a r=
edistribution dilemma. There are 3 types of proposals:</span></p><ol style=
=3D"margin-top: 0px; margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-sty=
le-type: lower-roman; font-size: 11pt; 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; white-space: pre;"><p dir=3D"ltr" styl=
e=3D"line-height: 1.38; text-align: justify; margin-top: 0pt; margin-bottom=
: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt; background-co=
lor: transparent; font-variant-numeric: normal; font-variant-east-asian: no=
rmal; font-variant-alternates: normal; vertical-align: baseline;">Allow any=
one to steal vulnerable coins, benefitting those who reach quantum capabili=
ty 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; 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; white-space: pre;"><p dir=3D"ltr" style=3D"line-heig=
ht: 1.38; text-align: justify; margin-top: 0pt; margin-bottom: 0pt;" role=
=3D"presentation"><span style=3D"font-size: 11pt; background-color: transpa=
rent; font-variant-numeric: normal; font-variant-east-asian: normal; font-v=
ariant-alternates: normal; vertical-align: baseline;">Allow throttled theft=
 of coins, which leads to RBF battles and ultimately miners subsidizing the=
ir revenue from lost coins.</span></p></li><li dir=3D"ltr" style=3D"list-st=
yle-type: lower-roman; font-size: 11pt; font-family: &quot;Courier New&quot=
;, monospace; color: rgb(0, 0, 0); background-color: transparent; font-vari=
ant-numeric: normal; font-variant-east-asian: normal; font-variant-alternat=
es: normal; vertical-align: baseline; white-space: pre;"><p dir=3D"ltr" sty=
le=3D"line-height: 1.38; text-align: justify; margin-top: 0pt; margin-botto=
m: 0pt;" role=3D"presentation"><span style=3D"font-size: 11pt; background-c=
olor: transparent; font-variant-numeric: normal; font-variant-east-asian: n=
ormal; font-variant-alternates: normal; vertical-align: baseline;">Allow no=
 one to steal vulnerable coins.</span></p></li></ol></li></ol></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;"><p dir=3D"ltr" style=3D"line-height: 1.38; text-align: ju=
stify; margin-top: 0pt; margin-bottom: 0pt;" role=3D"presentation"><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;">Minimizes 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: 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;"><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-col=
or: transparent; font-variant-numeric: normal; font-variant-east-asian: nor=
mal; font-variant-alternates: normal; vertical-align: baseline;">By disallo=
wing new spends to quantum vulnerable script types, we minimize the attack =
surface with each new UTXO.=C2=A0=C2=A0</span></p></li><li dir=3D"ltr" styl=
e=3D"list-style-type: lower-alpha; font-size: 11pt; font-family: &quot;Cour=
ier New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparen=
t; font-variant-numeric: normal; font-variant-east-asian: normal; font-vari=
ant-alternates: normal; vertical-align: baseline; white-space: pre;"><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;">Upgrades to Bitcoin have historically taken many years; this will haste=
n and speed up the adoption of new quantum resistant script types.=C2=A0</s=
pan></p></li><li dir=3D"ltr" style=3D"list-style-type: lower-alpha; 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;"><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-varian=
t-numeric: normal; font-variant-east-asian: normal; font-variant-alternates=
: normal; vertical-align: baseline;">With a clear deadline, industry stakeh=
olders will more readily upgrade existing infrastructure to ensure continui=
ty of services.=C2=A0=C2=A0</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); background-color: transparent; font-=
weight: 700; font-variant-numeric: normal; font-variant-east-asian: normal;=
 font-variant-alternates: normal; vertical-align: baseline; white-space: pr=
e;"><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-si=
ze: 11pt; background-color: transparent; font-variant-numeric: normal; font=
-variant-east-asian: normal; font-variant-alternates: normal; vertical-alig=
n: baseline;">Minimizes loss of access to funds=C2=A0</span></p><ol style=
=3D"margin-top: 0px; margin-bottom: 0px;"><li dir=3D"ltr" style=3D"list-sty=
le-type: lower-alpha; font-size: 11pt; 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; white-space: pre;"><p dir=3D"ltr" styl=
e=3D"line-height: 1.38; text-align: justify; margin-top: 0pt; margin-bottom=
: 12pt;" role=3D"presentation"><span style=3D"font-size: 11pt; background-c=
olor: transparent; font-variant-numeric: normal; font-variant-east-asian: n=
ormal; font-variant-alternates: normal; vertical-align: baseline;">If there=
 is sufficient demand and research proves possible, submitting a ZK proof o=
f knowledge of a BIP-39 seed phrase corresponding to  a public key hash or =
script hash would provide a trustless means for legacy outputs to be spent =
in a quantum resistant manner, even after the sunset.=C2=A0=C2=A0</span></p=
></li></ol></li></ul><br /><div dir=3D"ltr" style=3D"margin-left: 0pt;" ali=
gn=3D"left"><span style=3D"border: medium; border-collapse: collapse;"><spa=
n><span width=3D"143"></span><span width=3D"539"></span></span><span><span =
style=3D"height: 27.4463pt;"><span style=3D"border-width: 1pt; border-style=
: solid; border-color: rgb(0, 0, 0); vertical-align: top; padding: 5pt; ove=
rflow: 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;Co=
urier New&quot;, monospace; color: rgb(0, 0, 0); background-color: transpar=
ent; font-weight: 700; font-variant-numeric: normal; font-variant-east-asia=
n: normal; font-variant-alternates: normal; vertical-align: baseline;">Stak=
eholder</span></p></span><span style=3D"border-width: 1pt; border-style: so=
lid; border-color: rgb(0, 0, 0); vertical-align: top; padding: 5pt; overflo=
w: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; mar=
gin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-family: &quot;Courie=
r New&quot;, monospace; color: rgb(0, 0, 0); background-color: transparent;=
 font-weight: 700; font-variant-numeric: normal; font-variant-east-asian: n=
ormal; font-variant-alternates: normal; vertical-align: baseline;">Incentiv=
e to Upgrade</span></p></span></span><span style=3D"height: 53.5388pt;"><sp=
an 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 s=
tyle=3D"font-size: 11pt; font-family: &quot;Courier New&quot;, monospace; c=
olor: rgb(0, 0, 0); background-color: transparent; font-weight: 700; font-v=
ariant-numeric: normal; font-variant-east-asian: normal; font-variant-alter=
nates: normal; vertical-align: baseline;">Miners</span></p></span><span sty=
le=3D"border-width: 1pt; border-style: solid; border-color: rgb(0, 0, 0); v=
ertical-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: 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;">=E2=80=A2 Larger size PQ signatures along with incentive f=
or users to migrate will create more demand for block 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 style=3D"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;">=
=E2=80=A2 Post-Phase B, non-upgraded miners produce invalid blocks.</span><=
/p><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-botto=
m: 0pt;"><span style=3D"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;">=E2=80=A2 A quantum attack on Bitco=
in will significantly devalue both their hardware and Bitcoin as a whole.=
=C2=A0</span></p></span></span><span style=3D"height: 52pt;"><span style=3D=
"border-width: 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertic=
al-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"fon=
t-size: 11pt; font-family: &quot;Courier New&quot;, monospace; color: rgb(0=
, 0, 0); background-color: transparent; font-weight: 700; font-variant-nume=
ric: normal; font-variant-east-asian: normal; font-variant-alternates: norm=
al; vertical-align: baseline;">Institutional Holders</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" sty=
le=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;">=E2=80=A2 Fiduciary duty: failing to act to prevent a q=
uantum attack on Bitcoin would violate the fiduciary duty to shareholders.=
=C2=A0=C2=A0</span></p><p dir=3D"ltr" style=3D"line-height: 1.38; margin-to=
p: 0pt; margin-bottom: 0pt;"><span style=3D"font-size: 11pt; font-family: &=
quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: t=
ransparent; font-variant-numeric: normal; font-variant-east-asian: normal; =
font-variant-alternates: normal; vertical-align: baseline;">=E2=80=A2 Demon=
strating Bitcoin=E2=80=99s ability to effectively mitigate emerging threats=
 will prove Bitcoin to be an investment grade asset.</span></p></span></spa=
n><span style=3D"height: 52pt;"><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: 11pt; font-family: &q=
uot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background-color: tr=
ansparent; font-weight: 700; font-variant-numeric: normal; font-variant-eas=
t-asian: normal; font-variant-alternates: normal; vertical-align: baseline;=
">Exchanges &amp; Custodians</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; 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;">=E2=
=80=A2 Concentrated risk: a quantum hack could bankrupt them overnight.</sp=
an></p><p dir=3D"ltr" style=3D"line-height: 1.38; margin-top: 0pt; margin-b=
ottom: 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-alt=
ernates: normal; vertical-align: baseline;">=E2=80=A2 Early migration is ch=
eap relative to potential losses, potential lawsuits over improper custody =
and reputational damage.</span></p></span></span><span style=3D"height: 52p=
t;"><span style=3D"border-width: 1pt; border-style: solid; border-color: rg=
b(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;">Everyday Users</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; font-family: &quot;Courier New&quot;, monos=
pace; color: rgb(0, 0, 0); background-color: transparent; font-variant-nume=
ric: normal; font-variant-east-asian: normal; font-variant-alternates: norm=
al; vertical-align: baseline;">=E2=80=A2 Self-sovereign peace of mind.</spa=
n></p><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-=
variant-numeric: normal; font-variant-east-asian: normal; font-variant-alte=
rnates: normal; vertical-align: baseline;">=E2=80=A2 Sunset date creates a =
clear deadline and incentive to improve their security rather than an open-=
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-width:=
 1pt; border-style: solid; border-color: rgb(0, 0, 0); vertical-align: midd=
le; 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); 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;">Attackers</span></p></span><span style=3D"border-width: 1p=
t; border-style: solid; border-color: rgb(0, 0, 0); vertical-align: top; pa=
dding: 5pt; overflow: hidden;"><p dir=3D"ltr" style=3D"line-height: 1.38; m=
argin-top: 0pt; margin-bottom: 0pt;"><span style=3D"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;">=E2=80=
=A2 Economic incentive diminishes as sunset nears, stolen coins cannot be s=
pent 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; margin=
-bottom: 12pt;"><span style=3D"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;">Key Insigh=
t:</span><span style=3D"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;"> As mentioned earlier, the proposal=
 turns quantum security into a </span><span style=3D"font-size: 11pt; font-=
family: &quot;Courier New&quot;, monospace; color: rgb(0, 0, 0); background=
-color: transparent; font-style: italic; font-variant-numeric: normal; font=
-variant-east-asian: normal; font-variant-alternates: normal; vertical-alig=
n: baseline;">private incentive to upgrade</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: baseli=
ne;">.=C2=A0=C2=A0</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;">This is n=
ot an offensive attack, rather, it is defensive: our thesis is that the Bit=
coin ecosystem wishes to defend itself and its interests against those who =
would prefer to do nothing and allow a malicious actor to destroy both valu=
e and trust.=C2=A0=C2=A0</span></p><p dir=3D"ltr" style=3D"line-height: 1.3=
8; margin-top: 0pt; margin-bottom: 0pt;"><span style=3D"background-color: t=
ransparent; color: rgb(0, 0, 0); font-family: &quot;Courier New&quot;, mono=
space; font-size: 11pt; text-align: center;"><br /></span></p><blockquote s=
tyle=3D"margin: 0px 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); font-family: &quot;Courier New&quot;, monospace; font-size: =
11pt; text-align: center;">"Lost coins only make everyone else's coins wort=
h slightly more. Think of it as a donation to everyone." - Satoshi Nakamoto=
</span></blockquote><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 New&quot;, monospace; color: rgb(0, 0, 0); background-color=
: transparent; font-variant-numeric: normal; font-variant-east-asian: norma=
l; font-variant-alternates: normal; vertical-align: baseline;">If true, the=
 corollary is:</span></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; fon=
t-size: 11pt; text-align: center;"><br /></span></p><blockquote style=3D"ma=
rgin: 0px 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); font-family: &quot;Courier New&quot;, monospace; font-size: 11pt; text=
-align: center;">"Quantum recovered coins only make everyone else's coins w=
orth less. Think of it as a theft from everyone."</span></blockquote><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 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;">The timelines that we are proposing ar=
e meant to find the best balance between giving ample ability for account o=
wners to migrate while maintaining the integrity of the overall ecosystem t=
o avoid catastrophic attacks.=C2=A0=C2=A0</span></p><br /><span dir=3D"ltr"=
 style=3D"line-height: 1.38; margin-top: 18pt; margin-bottom: 4pt;"><span s=
tyle=3D"font-size: 17pt; 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;">Backward Compatibility</span></span><p dir=3D"ltr" =
style=3D"line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span sty=
le=3D"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;">As a series of soft forks, older nodes will continue =
to operate without modification. Non-upgraded nodes, however, will consider=
 all post-quantum witness programs as anyone-can-spend scripts. They are st=
rongly encouraged to upgrade in order to fully validate the new programs.</=
span></p><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;Cou=
rier New&quot;, monospace; color: rgb(0, 0, 0); background-color: transpare=
nt; font-variant-numeric: normal; font-variant-east-asian: normal; font-var=
iant-alternates: normal; vertical-align: baseline;">Non-upgraded wallets ca=
n receive and send bitcoin from non-upgraded and upgraded wallets until Pha=
se A. After Phase A, they can no longer receive from any other wallets and =
can only send to upgraded wallets.=C2=A0 After Phase B, both senders and re=
ceivers will require upgraded wallets.=C2=A0Phase C would likely require a =
loosening of consensus rules (a hard fork) to allow vulnerable funds recove=
ry via ZK proofs.</span></p></span></div>
</blockquote></div>

<p></p>

-- <br />
You received this message because you are subscribed to the Google Groups &=
quot;Bitcoin Development Mailing List&quot; group.<br />
To unsubscribe from this group and stop receiving emails from it, send an e=
mail to <a href=3D"mailto:bitcoindev+unsubscribe@googlegroups.com">bitcoind=
ev+unsubscribe@googlegroups.com</a>.<br />
To view this discussion visit <a href=3D"https://groups.google.com/d/msgid/=
bitcoindev/cfb00fb3-1eeb-40c5-acc3-50d1919d7dben%40googlegroups.com?utm_med=
ium=3Demail&utm_source=3Dfooter">https://groups.google.com/d/msgid/bitcoind=
ev/cfb00fb3-1eeb-40c5-acc3-50d1919d7dben%40googlegroups.com</a>.<br />

------=_Part_267155_1449090592.1753052079455--

------=_Part_267154_1311451799.1753052079455--