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Date: Sun, 13 Jul 2025 16:19:45 -0700 (PDT)
From: Tadge Dryja <rx@awsomnet.org>
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
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Subject: [bitcoindev] Re: A Post Quantum Migration Proposal
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Hi  =20

While I generally agree that "freeze" beats "steal", and that a lot of lead=
=20
time is good, I don't think this plan is viable.
To me the biggest problem is that it ties activation of a PQ output type to=
=20
*de*activation of EC output types.  That would mean that someone who wants=
=20
to keep using all the great stuff in libsecp256k1 should try to prevent=20
BIP360 from being activated.

Sure, there can be risks from CRQCs.  But this proposal would go the other=
=20
direction, disabling important functionality and even destroying coins=20
preemptively, in anticipation of something that may never happen.

Also, how do you define "quantum-vulnerable UTXO"?  Would any P2PKH, or=20
P2WPKH output count?  Or only P2PKH / P2WPKH outputs where the public key=
=20
is already known?  I can understand disabling spends from known-pubkey=20
outputs, but for addresses where the public key has never been revealed,=20
commit/reveal schemes (like the one I posted about & am working on a=20
follow-up post for) should safely let people spend from those outputs=20
indefinitely.

With no evidence of a QRQC, I can see how there would be people who'd say=
=20
"We might never really know if a CRQC exists, so we need to disable EC=20
spends out of caution" and others who'd say "Don't disable EC spends, since=
=20
that's destroying coins", and that could be a persistent disagreement.  But=
=20
I hope if we did in fact have a proof that a CRQC has broken secp256k1,=20
there would be significant agreement on freezing known-pubkey EC outputs.

-Tadge
On Saturday, July 12, 2025 at 8:46:09=E2=80=AFPM UTC-4 Jameson Lopp wrote:

> Building upon my earlier essay against allowing quantum recovery of=20
> 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 potentia=
l=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=20
>    addresses, 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=20
>    BIP proposing a fork to allow recovery of legacy UTXOs through ZK proo=
f 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 befo=
re 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 quantu=
m=20
>       computer as early as 2027-2030. [McKinsey=20
>       <https://www.mckinsey.com/~/media/mckinsey/business%20functions/mck=
insey%20digital/our%20insights/the%20year%20of%20quantum%20from%20concept%2=
0to%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=20
>       algorithms even if the pace of hardware improvements is slower. Alg=
orithms=20
>       are improving up to 20X=20
>       <https://security.googleblog.com/2025/05/tracking-cost-of-quantum-f=
actori.html>,=20
>       lowering the theoretical hardware requirements for breaking classic=
al=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;=20
>       those 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=20
>       keys then transfer all funds weeks or months later, in a covert ble=
ed to=20
>       not alert chain watchers. Q-Day may be only known much later if the=
 attack=20
>       withholds broadcasting transactions in order to postpone revealing =
their=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 pubkey=
s)=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 re=
main=20
>       undetected for as long as possible, while a malicious attacker will=
 attempt=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=20
>       coordinate wallets, exchanges, miners, and custodians. A clear, tim=
e-boxed=20
>       pathway is 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 sl=
ow 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=
=20
>    is both in place and being implemented to effectively deal with the th=
reat=20
>    of 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=20
>    unspendable, 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=
 Proof
>
> Users with frozen quantum vulnerable funds and a HD wallet seed phrase ca=
n=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 e=
xists=20
>    and is capable of breaking Bitcoin=E2=80=99s cryptography will damage =
faith in the=20
>    network .=20
>    -=20
>   =20
>    An attack on Bitcoin may not be economically motivated - an attacker=
=20
>    may be politically or maliciously motivated and may attempt to destroy=
=20
>    value and trust in Bitcoin rather than extract value.  There is no way=
 to=20
>    know in advance how, when, or why an attack may occur.  A defensive=20
>    position must be taken well in advance of any attack. =20
>    -=20
>   =20
>    Bitcoin=E2=80=99s current signatures (ECDSA/Schnorr) will be a tantali=
zing=20
>    target: any UTXO that has ever exposed its public key on-chain (roughl=
y 25=20
>    % of all bitcoin) could be stolen by a cryptographically relevant quan=
tum=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 ty=
pes.=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 correspo=
nding to=20
>       a public key hash or script hash would provide a trustless means fo=
r legacy=20
>       outputs to be spent in a quantum resistant manner, even after the s=
unset. =20
>      =20
>
> Stakeholder
>
> Incentive to Upgrade
>
> Miners
>
> =E2=80=A2 Larger size PQ signatures along with incentive for users to mig=
rate will=20
> create more demand for block space and thus higher fees collected by mine=
rs.
>
> =E2=80=A2 Post-Phase B, non-upgraded miners produce invalid blocks.
>
> =E2=80=A2 A quantum attack on Bitcoin will significantly devalue both the=
ir=20
> hardware and Bitcoin as a whole.=20
>
> Institutional Holders
>
> =E2=80=A2 Fiduciary duty: failing to act to prevent a quantum attack on B=
itcoin=20
> would violate the fiduciary duty to shareholders. =20
>
> =E2=80=A2 Demonstrating Bitcoin=E2=80=99s ability to effectively mitigate=
 emerging 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, potentia=
l=20
> lawsuits 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 t=
heir=20
> security rather than an open-ended =E2=80=9Csome day=E2=80=9D that invite=
s procrastination.
>
> Attackers
>
> =E2=80=A2 Economic incentive diminishes as sunset nears, stolen coins can=
not be=20
> spent after Q-day.
>
> Key Insight: As mentioned earlier, the proposal turns quantum security=20
> into 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. Thin=
k=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 encourage=
d=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 Phas=
e=20
> B, both senders and receivers will require upgraded wallets. Phase C woul=
d=20
> likely require a loosening of consensus rules (a hard fork) to allow=20
> vulnerable funds recovery via ZK proofs.
>

--=20
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Hi =C2=A0 <br /><br />While I generally agree that "freeze" beats "steal", =
and that a lot of lead time is good, I don't think this plan is viable.<br =
/>To me the biggest problem is that it ties activation of a PQ output type =
to *de*activation of EC output types. =C2=A0That would mean that someone wh=
o wants to keep using all the great stuff in libsecp256k1 should try to pre=
vent BIP360 from being activated.<br /><br />Sure, there can be risks from =
CRQCs. =C2=A0But this proposal would go the other direction, disabling impo=
rtant functionality and even destroying coins preemptively, in anticipation=
 of something that may never happen.<br /><br />Also, how do you define "qu=
antum-vulnerable UTXO"? =C2=A0Would any P2PKH, or P2WPKH output count? =C2=
=A0Or only P2PKH / P2WPKH outputs where the public key is already known? =
=C2=A0I can understand disabling spends from known-pubkey outputs, but for =
addresses where the public key has never been revealed, commit/reveal schem=
es (like the one I posted about &amp; am working on a follow-up post for) s=
hould safely let people spend from those outputs indefinitely.<br /><br />W=
ith no evidence of a QRQC, I can see how there would be people who'd say "W=
e might never really know if a CRQC exists, so we need to disable EC spends=
 out of caution" and others who'd say "Don't disable EC spends, since that'=
s destroying coins", and that could be a persistent disagreement. =C2=A0But=
 I hope if we did in fact have a proof that a CRQC has broken secp256k1, th=
ere would be significant agreement on freezing known-pubkey EC outputs.<br =
/><div><br /></div><div>-Tadge</div><div class=3D"gmail_quote"><div dir=3D"=
auto" class=3D"gmail_attr">On Saturday, July 12, 2025 at 8:46:09=E2=80=AFPM=
 UTC-4 Jameson Lopp wrote:<br/></div><blockquote class=3D"gmail_quote" styl=
e=3D"margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); paddin=
g-left: 1ex;"><div dir=3D"ltr"><span><p dir=3D"ltr" style=3D"line-height:1.=
44;background-color:rgb(255,255,255);margin-top:12pt;margin-bottom:0pt;padd=
ing:0pt 0pt 12pt"><span style=3D"font-size:11pt;font-family:&quot;Courier N=
ew&quot;,monospace;color:rgb(34,34,34);background-color:transparent;font-we=
ight:400;font-style:normal;font-variant:normal;text-decoration:none;vertica=
l-align:baseline;white-space:pre-wrap">Building upon my earlier essay </spa=
n><a href=3D"https://groups.google.com/g/bitcoindev/c/uUK6py0Yjq0/m/6peEaa9=
0AQAJ" style=3D"text-decoration:none" target=3D"_blank" rel=3D"nofollow" da=
ta-saferedirecturl=3D"https://www.google.com/url?hl=3Den&amp;q=3Dhttps://gr=
oups.google.com/g/bitcoindev/c/uUK6py0Yjq0/m/6peEaa90AQAJ&amp;source=3Dgmai=
l&amp;ust=3D1752534687424000&amp;usg=3DAOvVaw1JYFVJnNr4LjNmOn88N0Wh"><span =
style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;color=
:rgb(17,85,204);background-color:transparent;font-weight:400;font-style:nor=
mal;font-variant:normal;text-decoration:underline;vertical-align:baseline;w=
hite-space:pre-wrap">against allowing quantum recovery of bitcoin</span></a=
><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospac=
e;color:rgb(34,34,34);background-color:transparent;font-weight:400;font-sty=
le:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;=
white-space:pre-wrap"> I wish to formalize a proposal after several months =
of discussions.</span></p><p dir=3D"ltr" style=3D"line-height:1.44;backgrou=
nd-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;fon=
t-style:normal;font-variant:normal;text-decoration:none;vertical-align:base=
line;white-space:pre-wrap">This proposal does not delve into the multitude =
of issues regarding post quantum cryptography and trade-offs of different s=
chemes, but rather is meant to specifically address the issues of incentivi=
zing adoption and migration of funds </span><span style=3D"font-size:11pt;f=
ont-family:&quot;Courier New&quot;,monospace;color:rgb(34,34,34);background=
-color:transparent;font-weight:400;font-variant:normal;text-decoration:none=
;vertical-align:baseline;white-space:pre-wrap"><i>after</i></span><span sty=
le=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rg=
b(34,34,34);background-color:transparent;font-weight:400;font-style:normal;=
font-variant:normal;text-decoration:none;vertical-align:baseline;white-spac=
e: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=
);margin-top:0pt;margin-bottom:12pt"><span style=3D"font-size:11pt;font-fam=
ily:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:tra=
nsparent;font-weight:400;font-style:normal;font-variant:normal;text-decorat=
ion:none;vertical-align:baseline;white-space:pre-wrap">As such, this propos=
al requires P2QRH as described in BIP-360 or potential future proposals.</s=
pan></p><h2 dir=3D"ltr" style=3D"line-height:1.38;margin-top:18pt;margin-bo=
ttom:4pt"><span style=3D"font-size:17pt;font-family:&quot;Courier New&quot;=
,monospace;color:rgb(0,0,0);background-color:transparent;font-variant-numer=
ic:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ver=
tical-align:baseline">Abstract</span></h2><p dir=3D"ltr" style=3D"line-heig=
ht:1.38;margin-top:12pt;margin-bottom:12pt"><span style=3D"font-size:11pt;f=
ont-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-co=
lor:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;=
font-variant-alternates:normal;vertical-align:baseline">This proposal follo=
ws the implementation of post-quantum (PQ) output type (P2QRH) and introduc=
es a pre-announced sunset of legacy ECDSA/Schnorr signatures. It turns quan=
tum 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;f=
ont-style:italic;font-variant-numeric:normal;font-variant-east-asian:normal=
;font-variant-alternates:normal;vertical-align:baseline">private incentive<=
/span><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,mon=
ospace;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:n=
ormal;font-variant-east-asian:normal;font-variant-alternates:normal;vertica=
l-align:baseline">: fail to upgrade and you will certainly lose access to y=
our funds, creating a certainty where 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-size:11pt;font-family:&quot;Courier New&quot;,mo=
nospace;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:=
normal;font-variant-east-asian:normal;font-variant-alternates:normal;vertic=
al-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"fon=
t-size:11pt;background-color:transparent;font-weight:700;font-variant-numer=
ic:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ver=
tical-align:baseline">Phase A:</span><span style=3D"font-size:11pt;backgrou=
nd-color:transparent;font-variant-numeric:normal;font-variant-east-asian:no=
rmal;font-variant-alternates:normal;vertical-align:baseline"> Disallows sen=
ding of any funds to quantum-vulnerable addresses, hastening the adoption o=
f P2QRH address types.</span></p></li><li dir=3D"ltr" style=3D"list-style-t=
ype: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:base=
line;white-space:pre"><p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0=
pt;margin-bottom:0pt" role=3D"presentation"><span style=3D"font-size:11pt;b=
ackground-color:transparent;font-weight:700;font-variant-numeric:normal;fon=
t-variant-east-asian:normal;font-variant-alternates:normal;vertical-align:b=
aseline">Phase B:</span><span style=3D"font-size:11pt;background-color:tran=
sparent;font-variant-numeric:normal;font-variant-east-asian:normal;font-var=
iant-alternates:normal;vertical-align:baseline"> Renders ECDSA/Schnorr spen=
ds invalid, preventing all spending of funds in quantum-vulnerable UTXOs. T=
his is triggered by a well-publicized flag-day roughly five years after act=
ivation.</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);ba=
ckground-color:transparent;font-variant-numeric:normal;font-variant-east-as=
ian:normal;font-variant-alternates:normal;vertical-align:baseline;white-spa=
ce:pre"><p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-bott=
om:6pt" role=3D"presentation"><span style=3D"font-size:11pt;background-colo=
r:transparent;font-weight:700;font-variant-numeric:normal;font-variant-east=
-asian:normal;font-variant-alternates:normal;vertical-align:baseline">Phase=
 C (optional):</span><span style=3D"font-size:11pt;background-color:transpa=
rent;font-variant-numeric:normal;font-variant-east-asian:normal;font-varian=
t-alternates:normal;vertical-align:baseline"> Pending further research and =
demand, a separate BIP proposing a fork to allow recovery of legacy UTXOs t=
hrough ZK proof of possession of BIP-39 seed phrase.=C2=A0=C2=A0</span></p>=
</li></ul><h2 dir=3D"ltr" style=3D"line-height:1.38;text-align:justify;marg=
in-top:14pt;margin-bottom:6pt"><span style=3D"font-size:16pt;font-family:&q=
uot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transpare=
nt;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-=
alternates:normal;vertical-align:baseline">Motivation</span></h2><p dir=3D"=
ltr" style=3D"line-height:1.38;text-align:justify;margin-top:12pt;margin-bo=
ttom:12pt"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot=
;,monospace;color:rgb(0,0,0);background-color:transparent;font-variant-nume=
ric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ve=
rtical-align:baseline">We seek to secure the value of the UTXO set</span><s=
pan style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;c=
olor:rgb(0,0,0);background-color:transparent;font-weight:700;font-variant-n=
umeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal=
;vertical-align:baseline"> </span><span style=3D"font-size:11pt;font-family=
:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transp=
arent;font-variant-numeric:normal;font-variant-east-asian:normal;font-varia=
nt-alternates:normal;vertical-align:baseline">and minimize incentives for q=
uantum attacks. This proposal is radically different from any in Bitcoin=E2=
=80=99s history just as the threat posed by quantum computing is radically =
different from any other threat in Bitcoin=E2=80=99s history.=C2=A0 Never b=
efore has Bitcoin faced an existential threat to its cryptographic primitiv=
es. A successful quantum attack on Bitcoin would result in significant econ=
omic disruption and damage across the entire ecosystem. Beyond its impact o=
n price, the ability of miners to provide network security may be significa=
ntly impacted.=C2=A0=C2=A0</span></p><ul style=3D"margin-top:0px;margin-bot=
tom: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-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:12pt;margin-bottom:0pt" role=
=3D"presentation"><span style=3D"font-size:11pt;background-color:transparen=
t;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:norma=
l;font-variant-alternates:normal;vertical-align:baseline">Accelerating quan=
tum progress.</span><span style=3D"font-size:11pt;background-color:transpar=
ent;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant=
-alternates:normal;vertical-align:baseline">=C2=A0</span></p></li><ul style=
=3D"margin-top:0px;margin-bottom:0px"><li dir=3D"ltr" style=3D"list-style-t=
ype:circle;font-size:11pt;font-family:&quot;Courier New&quot;,monospace;col=
or:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font=
-variant-east-asian:normal;font-variant-alternates:normal;vertical-align:ba=
seline;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-variant-east=
-asian:normal;font-variant-alternates:normal;vertical-align:baseline">NIST =
ratified three production-grade PQ signature schemes in 2024; academic road=
-maps now estimate a cryptographically-relevant quantum computer as early a=
s 2027-2030. [</span><a href=3D"https://www.mckinsey.com/~/media/mckinsey/b=
usiness%20functions/mckinsey%20digital/our%20insights/the%20year%20of%20qua=
ntum%20from%20concept%20to%20reality%20in%202025/quantum-monitor-2025.pdf?s=
houldIndex=3Dfalse" style=3D"text-decoration-line:none" target=3D"_blank" r=
el=3D"nofollow" data-saferedirecturl=3D"https://www.google.com/url?hl=3Den&=
amp;q=3Dhttps://www.mckinsey.com/~/media/mckinsey/business%2520functions/mc=
kinsey%2520digital/our%2520insights/the%2520year%2520of%2520quantum%2520fro=
m%2520concept%2520to%2520reality%2520in%25202025/quantum-monitor-2025.pdf?s=
houldIndex%3Dfalse&amp;source=3Dgmail&amp;ust=3D1752534687424000&amp;usg=3D=
AOvVaw0hkb56r0Ina1pZwUk4M74d"><span style=3D"font-size:11pt;background-colo=
r:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;fo=
nt-variant-alternates:normal;text-decoration-line:underline;vertical-align:=
baseline">McKinsey</span></a><span style=3D"font-size:11pt;background-color=
:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;fon=
t-variant-alternates:normal;vertical-align:baseline">]</span></p></li></ul>=
<li dir=3D"ltr" style=3D"list-style-type:disc;font-size:11pt;font-family:&q=
uot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transpare=
nt;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:norm=
al;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;back=
ground-color:transparent;font-variant-numeric:normal;font-variant-east-asia=
n:normal;font-variant-alternates:normal;vertical-align:baseline">Quantum al=
gorithms are rapidly improving</span></p></li><ul style=3D"margin-top:0px;m=
argin-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);backgr=
ound-color:transparent;font-variant-numeric:normal;font-variant-east-asian:=
normal;font-variant-alternates:normal;vertical-align:baseline;white-space:p=
re"><p dir=3D"ltr" style=3D"line-height:1.38;text-align:justify;margin-top:=
0pt;margin-bottom:0pt" role=3D"presentation"><span style=3D"font-size:11pt;=
background-color:transparent;font-variant-numeric:normal;font-variant-east-=
asian:normal;font-variant-alternates:normal;vertical-align:baseline">The sa=
fety envelope is shrinking by dramatic increases in algorithms even if the =
pace of hardware improvements is slower. Algorithms are <a href=3D"https://=
security.googleblog.com/2025/05/tracking-cost-of-quantum-factori.html" targ=
et=3D"_blank" rel=3D"nofollow" data-saferedirecturl=3D"https://www.google.c=
om/url?hl=3Den&amp;q=3Dhttps://security.googleblog.com/2025/05/tracking-cos=
t-of-quantum-factori.html&amp;source=3Dgmail&amp;ust=3D1752534687424000&amp=
;usg=3DAOvVaw2NPPXI2WkIWYTWo_3owbUB">improving up to 20X</a>, lowering the =
theoretical hardware requirements for breaking classical encryption.</span>=
</p></li></ul><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-c=
olor: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" ro=
le=3D"presentation"><span style=3D"font-size:11pt;background-color:transpar=
ent;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:nor=
mal;font-variant-alternates:normal;vertical-align:baseline">Bitcoin=E2=80=
=99s exposed public keys.</span><span style=3D"font-size:11pt;background-co=
lor:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;=
font-variant-alternates:normal;vertical-align:baseline">=C2=A0</span></p></=
li><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;,m=
onospace;color:rgb(0,0,0);background-color:transparent;font-variant-numeric=
:normal;font-variant-east-asian:normal;font-variant-alternates:normal;verti=
cal-align:baseline;white-space:pre"><p dir=3D"ltr" style=3D"line-height:1.3=
8;margin-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:bas=
eline">Roughly 25% of all bitcoin have revealed a public key on-chain; thos=
e UTXOs could be stolen with sufficient quantum power.=C2=A0=C2=A0</span></=
p></li></ul><li dir=3D"ltr" style=3D"list-style-type:disc;font-size:11pt;fo=
nt-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-col=
or:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;f=
ont-variant-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;marg=
in-bottom:0pt" role=3D"presentation"><span style=3D"font-size:11pt;backgrou=
nd-color:transparent;font-weight:700;font-variant-numeric:normal;font-varia=
nt-east-asian:normal;font-variant-alternates:normal;vertical-align:baseline=
">We may not know the attack is underway.=C2=A0</span></p></li><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-va=
riant-east-asian:normal;font-variant-alternates:normal;vertical-align:basel=
ine;white-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 style=
=3D"font-size:11pt;background-color:transparent;font-variant-numeric:normal=
;font-variant-east-asian:normal;font-variant-alternates:normal;vertical-ali=
gn:baseline">Quantum attackers could compute the private key for known publ=
ic 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 later if the attack=
 withholds broadcasting transactions in order to postpone revealing their c=
apabilities.</span></p></li></ul><li dir=3D"ltr" style=3D"list-style-type:d=
isc;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;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"font-=
size:11pt;background-color:transparent;font-variant-numeric:normal;font-var=
iant-east-asian:normal;font-variant-alternates:normal;vertical-align:baseli=
ne">Private keys become public.=C2=A0</span></p></li><ul style=3D"margin-to=
p:0px;margin-bottom:0px"><li dir=3D"ltr" style=3D"list-style-type:circle;fo=
nt-size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0)=
;background-color:transparent;font-weight:700;font-variant-numeric:normal;f=
ont-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:1=
1pt;background-color:transparent;font-weight:400;font-variant-numeric:norma=
l;font-variant-east-asian:normal;font-variant-alternates:normal;vertical-al=
ign:baseline">Assuming that quantum computers are able to maintain their cu=
rrent trajectories and overcome existing engineering obstacles, there is a =
near certain chance that all P2PK (and other outputs with exposed pubkeys) =
private keys will be found and used to steal the funds.</span></p></li></ul=
><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:transpar=
ent;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:nor=
mal;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:trans=
parent;font-variant-numeric:normal;font-variant-east-asian:normal;font-vari=
ant-alternates:normal;vertical-align:baseline">Impossible to know motivatio=
ns.=C2=A0</span></p></li><ul style=3D"margin-top:0px;margin-bottom:0px"><li=
 dir=3D"ltr" style=3D"list-style-type:circle;font-size:11pt;font-family:&qu=
ot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transparen=
t;font-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-bottom:0pt" r=
ole=3D"presentation"><span style=3D"font-size:11pt;background-color:transpa=
rent;font-weight:400;font-variant-numeric:normal;font-variant-east-asian:no=
rmal;font-variant-alternates:normal;vertical-align:baseline">Prior to a qua=
ntum attack, it is impossible to know the motivations of the attacker.=C2=
=A0 An economically motivated attacker will try to remain undetected for as=
 long as possible, while a malicious attacker will attempt to destroy as mu=
ch value as possible.=C2=A0=C2=A0</span></p></li></ul><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-numer=
ic:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ver=
tical-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-weight:700;font-variant-nu=
meric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;=
vertical-align:baseline">Upgrade inertia.</span><span style=3D"font-size:11=
pt;background-color:transparent;font-variant-numeric:normal;font-variant-ea=
st-asian:normal;font-variant-alternates:normal;vertical-align:baseline">=C2=
=A0</span></p></li><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;C=
ourier New&quot;,monospace;color:rgb(0,0,0);background-color:transparent;fo=
nt-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alter=
nates: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-n=
umeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal=
;vertical-align:baseline">Coordinating wallets, exchanges, miners and custo=
dians historically takes years.</span></p></li><li dir=3D"ltr" style=3D"lis=
t-style-type:circle;font-size:11pt;font-family:&quot;Courier New&quot;,mono=
space;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:no=
rmal;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"presentation"><=
span style=3D"font-size:11pt;background-color:transparent;font-variant-nume=
ric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ve=
rtical-align:baseline">The longer we postpone migration, the harder it beco=
mes to coordinate wallets, exchanges, miners, and custodians. A clear, time=
-boxed pathway is the only credible defense.</span></p></li><li dir=3D"ltr"=
 style=3D"list-style-type:circle;font-size:11pt;font-family:&quot;Courier N=
ew&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-varia=
nt-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:no=
rmal;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"p=
resentation"><span style=3D"font-size:11pt;background-color:transparent;fon=
t-variant-numeric:normal;font-variant-east-asian:normal;font-variant-altern=
ates:normal;vertical-align:baseline">Coordinating distributed groups is mor=
e prone to delay, even if everyone has similar motivations. Historically, B=
itcoin has been slow to adopt code changes, often taking multiple years to =
be approved.</span></p></li></ul></ul><h2 dir=3D"ltr" style=3D"line-height:=
1.38;text-align:justify;margin-top:14pt;margin-bottom:6pt"><span style=3D"f=
ont-size:16pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0=
);background-color:transparent;font-variant-numeric:normal;font-variant-eas=
t-asian:normal;font-variant-alternates:normal;vertical-align:baseline">Bene=
fits at a Glance</span></h2><ul style=3D"margin-top:0px;margin-bottom:0px">=
<li dir=3D"ltr" style=3D"list-style-type:disc;font-size:11pt;font-family:Ar=
ial,sans-serif;color:rgb(0,0,0);background-color:transparent;font-variant-n=
umeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal=
;vertical-align:baseline;white-space:pre"><p dir=3D"ltr" style=3D"line-heig=
ht:1.38;text-align:justify;margin-top:12pt;margin-bottom:0pt" role=3D"prese=
ntation"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,=
monospace;background-color:transparent;font-weight:700;font-variant-numeric=
:normal;font-variant-east-asian:normal;font-variant-alternates:normal;verti=
cal-align:baseline">Resilience:</span><span style=3D"font-size:11pt;font-fa=
mily:&quot;Courier New&quot;,monospace;background-color:transparent;font-va=
riant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates=
:normal;vertical-align:baseline"> Bitcoin protocol remains secure for the f=
oreseeable future without waiting for a last-minute emergency.</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-varian=
t-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:nor=
mal;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" role=3D"pre=
sentation"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot=
;,monospace;background-color:transparent;font-weight:700;font-variant-numer=
ic:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ver=
tical-align:baseline">Certainty</span><span style=3D"font-size:11pt;font-fa=
mily:&quot;Courier New&quot;,monospace;background-color:transparent;font-va=
riant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates=
:normal;vertical-align:baseline">: Bitcoin users and stakeholders gain cert=
ainty that a plan is both in place and being implemented to effectively dea=
l 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;font-size:11pt;font-family:Ari=
al,sans-serif;color:rgb(0,0,0);background-color:transparent;font-variant-nu=
meric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;=
vertical-align:baseline;white-space:pre"><p dir=3D"ltr" style=3D"line-heigh=
t:1.38;text-align:justify;margin-top:0pt;margin-bottom:0pt" role=3D"present=
ation"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,mo=
nospace;background-color:transparent;font-weight:700;font-variant-numeric:n=
ormal;font-variant-east-asian:normal;font-variant-alternates:normal;vertica=
l-align:baseline">Clarity:</span><span style=3D"font-size:11pt;font-family:=
&quot;Courier New&quot;,monospace;background-color:transparent;font-variant=
-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:norm=
al;vertical-align:baseline"> A single, publicized timeline aligns the entir=
e ecosystem (wallets, exchanges, hardware vendors).</span></p></li><li dir=
=3D"ltr" style=3D"list-style-type:disc;font-size:11pt;font-family:Arial,san=
s-serif;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:=
normal;font-variant-east-asian:normal;font-variant-alternates:normal;vertic=
al-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"presentation=
"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospa=
ce;background-color:transparent;font-weight:700;font-variant-numeric:normal=
;font-variant-east-asian:normal;font-variant-alternates:normal;vertical-ali=
gn:baseline">Supply Discipline:</span><span style=3D"font-size:11pt;font-fa=
mily:&quot;Courier New&quot;,monospace;background-color:transparent;font-va=
riant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates=
:normal;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" data-safere=
directurl=3D"https://www.google.com/url?hl=3Den&amp;q=3Dhttps://bitcointalk=
.org/index.php?topic%3D198.msg1647%23msg1647&amp;source=3Dgmail&amp;ust=3D1=
752534687425000&amp;usg=3DAOvVaw0K1wYoahJ13f6dubHcjG7W">as Satoshi describe=
d</a></span><span style=3D"font-size:11pt;font-family:&quot;Courier New&quo=
t;,monospace;background-color:transparent;font-variant-numeric:normal;font-=
variant-east-asian:normal;font-variant-alternates:normal;vertical-align:bas=
eline">.=C2=A0=C2=A0</span></p></li></ul><h2 dir=3D"ltr" style=3D"line-heig=
ht:1.38;text-align:justify;margin-top:12pt;margin-bottom:12pt"><span style=
=3D"font-size:16pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(=
0,0,0);background-color:transparent;font-variant-numeric:normal;font-varian=
t-east-asian:normal;font-variant-alternates:normal;vertical-align:baseline"=
>Specification</span></h2><h2 dir=3D"ltr" style=3D"line-height:1.38;text-al=
ign:justify;margin-top:12pt;margin-bottom:12pt"><span style=3D"font-weight:=
normal"><div dir=3D"ltr" style=3D"margin-left:0pt" align=3D"left"><table st=
yle=3D"border:none;border-collapse:collapse"><colgroup><col width=3D"181"><=
col width=3D"224"><col width=3D"137"><col width=3D"130"></colgroup><tbody><=
tr style=3D"height:0pt"><td style=3D"border-width:1pt;border-style:solid;bo=
rder-color:rgb(0,0,0);vertical-align:top;padding:5pt;overflow:hidden"><p di=
r=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&qu=
ot;,monospace;color:rgb(0,0,0);background-color:transparent;font-weight:700=
;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-al=
ternates:normal;vertical-align:baseline">Phase</span></p></td><td 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;t=
ext-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);backgr=
ound-color:transparent;font-weight:700;font-variant-numeric:normal;font-var=
iant-east-asian:normal;font-variant-alternates:normal;vertical-align:baseli=
ne">What Happens</span></p></td><td style=3D"border-width:1pt;border-style:=
solid;border-color:rgb(0,0,0);vertical-align:top;padding:5pt;overflow:hidde=
n"><p dir=3D"ltr" style=3D"line-height:1.38;text-align:center;margin-top:0p=
t;margin-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-we=
ight:700;font-variant-numeric:normal;font-variant-east-asian:normal;font-va=
riant-alternates:normal;vertical-align:baseline">Who Must Act</span></p></t=
d><td 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"lin=
e-height:1.38;text-align:center;margin-top:0pt;margin-bottom:0pt"><span sty=
le=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rg=
b(0,0,0);background-color:transparent;font-weight:700;font-variant-numeric:=
normal;font-variant-east-asian:normal;font-variant-alternates:normal;vertic=
al-align:baseline">Time Horizon</span></p></td></tr><tr style=3D"height:0pt=
"><td 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"lin=
e-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"font-size:11=
pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);backgroun=
d-color:transparent;font-weight:700;font-variant-numeric:normal;font-varian=
t-east-asian:normal;font-variant-alternates:normal;vertical-align:baseline"=
>Phase A - </span><span style=3D"font-size:11pt;font-family:&quot;Courier N=
ew&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-varia=
nt-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:no=
rmal;vertical-align:baseline">Disallow spends to legacy script types</span>=
</p></td><td 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" st=
yle=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"fo=
nt-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;vertical-align:baseline">Permi=
tted sends are from legacy scripts to P2QRH scripts</span></p></td><td styl=
e=3D"border-width:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-a=
lign:middle;padding:5pt;overflow:hidden"><p dir=3D"ltr" style=3D"line-heigh=
t: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-style:italic;font-variant-numeric:normal;font-variant-eas=
t-asian:normal;font-variant-alternates:normal;vertical-align:baseline">Ever=
yone</span><span style=3D"font-size:10pt;font-family:&quot;Courier New&quot=
;,monospace;color:rgb(0,0,0);background-color:transparent;font-variant-nume=
ric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ve=
rtical-align:baseline"> holding or accepting BTC.</span></p></td><td style=
=3D"border-width:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-al=
ign:middle;padding:5pt;overflow:hidden"><p dir=3D"ltr" style=3D"line-height=
:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"font-size:10pt;font-=
family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:=
transparent;font-variant-numeric:normal;font-variant-east-asian:normal;font=
-variant-alternates:normal;vertical-align:baseline">3 years after BIP-360 i=
mplementation</span></p></td></tr><tr style=3D"height:0pt"><td style=3D"bor=
der-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;marg=
in-top:0pt;margin-bottom:0pt"><span style=3D"font-size:11pt;font-family:&qu=
ot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transparen=
t;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:norma=
l;font-variant-alternates:normal;vertical-align:baseline">Phase B =E2=80=93=
 </span><span style=3D"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;verti=
cal-align:baseline">Disallow spends from quantum vulnerable outputs</span><=
/p></td><td 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" sty=
le=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"fon=
t-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;vertical-align:baseline">At a p=
reset block-height, nodes reject transactions that rely on ECDSA/Schnorr ke=
ys.=C2=A0</span></p></td><td style=3D"border-width:1pt;border-style:solid;b=
order-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;,monospace;=
color:rgb(0,0,0);background-color:transparent;font-style:italic;font-varian=
t-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:nor=
mal;vertical-align:baseline">Everyone</span><span style=3D"font-size:10pt;f=
ont-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-co=
lor:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;=
font-variant-alternates:normal;vertical-align:baseline"> holding or accepti=
ng BTC.</span></p></td><td style=3D"border-width:1pt;border-style:solid;bor=
der-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"><sp=
an style=3D"font-size:10pt;font-family:&quot;Courier New&quot;,monospace;co=
lor:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;fon=
t-variant-east-asian:normal;font-variant-alternates:normal;vertical-align:b=
aseline">2 years after Phase A activation.</span></p></td></tr><tr style=3D=
"height:0pt"><td 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" s=
tyle=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"f=
ont-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-alig=
n:baseline">Phase C =E2=80=93 </span><span style=3D"font-size:11pt;font-fam=
ily:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:tra=
nsparent;font-variant-numeric:normal;font-variant-east-asian:normal;font-va=
riant-alternates:normal;vertical-align:baseline">Re-enable spends from quan=
tum vulnerable outputs via ZK Proof</span></p></td><td style=3D"border-widt=
h:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-align:middle;padd=
ing:5pt;overflow:hidden"><p dir=3D"ltr" style=3D"line-height:1.38;margin-to=
p:0pt;margin-bottom:0pt"><span style=3D"font-size:10pt;font-family:&quot;Co=
urier New&quot;,monospace;color:rgb(0,0,0);background-color:transparent;fon=
t-variant-numeric:normal;font-variant-east-asian:normal;font-variant-altern=
ates:normal;vertical-align:baseline">Users with frozen quantum vulnerable f=
unds and a HD wallet seed phrase can construct a quantum safe ZK proof to r=
ecover funds.</span></p></td><td style=3D"border-width:1pt;border-style:sol=
id;border-color:rgb(0,0,0);vertical-align:middle;padding:5pt;overflow:hidde=
n"><p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-bottom:0p=
t"><span style=3D"font-size:10pt;font-family:&quot;Courier New&quot;,monosp=
ace;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:norm=
al;font-variant-east-asian:normal;font-variant-alternates:normal;vertical-a=
lign:baseline">Users who failed to migrate funds before Phase B.</span></p>=
</td><td 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;,monospace;color:rgb(0,0,0);ba=
ckground-color:transparent;font-variant-numeric:normal;font-variant-east-as=
ian:normal;font-variant-alternates:normal;vertical-align:baseline">TBD pend=
ing research, demand, and consensus.</span></p></td></tr></tbody></table></=
div></span></h2><h2 dir=3D"ltr" style=3D"line-height:1.38;margin-top:14pt;m=
argin-bottom:6pt"><span style=3D"font-size:16pt;font-family:&quot;Courier N=
ew&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-weigh=
t:700;font-style:normal;font-variant:normal;text-decoration:none;vertical-a=
lign:baseline;white-space:pre-wrap">Rationale</span></h2><ul style=3D"margi=
n-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-variant-ea=
st-asian:normal;font-variant-alternates:normal;vertical-align:baseline;whit=
e-space:pre"><p dir=3D"ltr" style=3D"line-height:1.38;text-align:justify;ma=
rgin-top:12pt;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:baseli=
ne">Even if Bitcoin is not a primary initial 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 fait=
h in the network .=C2=A0</span></p></li><li dir=3D"ltr" style=3D"list-style=
-type:disc;font-size:11pt;font-family:&quot;Courier New&quot;,monospace;col=
or:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font=
-variant-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 styl=
e=3D"font-size:11pt;background-color:transparent;font-variant-numeric:norma=
l;font-variant-east-asian:normal;font-variant-alternates:normal;vertical-al=
ign:baseline">An attack on Bitcoin may not be economically motivated - an a=
ttacker may be politically or maliciously motivated and may attempt to dest=
roy 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 defe=
nsive position must be taken well in advance of any attack.=C2=A0=C2=A0</sp=
an></p></li><li dir=3D"ltr" style=3D"list-style-type:disc;font-size:11pt;fo=
nt-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-col=
or:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;f=
ont-variant-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;marg=
in-bottom:0pt" role=3D"presentation"><span style=3D"font-size:11pt;backgrou=
nd-color:transparent;font-variant-numeric:normal;font-variant-east-asian:no=
rmal;font-variant-alternates:normal;vertical-align:baseline">Bitcoin=E2=80=
=99s current signatures (ECDSA/Schnorr) will be a tantalizing target: any U=
TXO that has ever exposed its public key on-chain (roughly 25 % of all bitc=
oin) could be stolen by a cryptographically relevant quantum computer.</spa=
n></p></li><li dir=3D"ltr" style=3D"list-style-type:disc;font-size:11pt;fon=
t-family:Arial,sans-serif;color:rgb(0,0,0);background-color:transparent;fon=
t-variant-numeric:normal;font-variant-east-asian:normal;font-variant-altern=
ates: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" r=
ole=3D"presentation"><span style=3D"font-size:11pt;font-family:&quot;Courie=
r New&quot;,monospace;background-color:transparent;font-weight:700;font-var=
iant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:=
normal;vertical-align:baseline">Existing Proposals are Insufficient.</span>=
<span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace=
;background-color:transparent;font-variant-numeric:normal;font-variant-east=
-asian:normal;font-variant-alternates:normal;vertical-align:baseline">=C2=
=A0=C2=A0</span></p></li><ol style=3D"margin-top:0px;margin-bottom:0px"><li=
 dir=3D"ltr" style=3D"list-style-type:lower-alpha;font-size:11pt;font-famil=
y:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:trans=
parent;font-variant-numeric:normal;font-variant-east-asian:normal;font-vari=
ant-alternates:normal;vertical-align:baseline;white-space:pre"><p dir=3D"lt=
r" style=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-color=
:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;fon=
t-variant-alternates:normal;vertical-align:baseline">Any proposal that allo=
ws for the quantum theft of =E2=80=9Clost=E2=80=9D bitcoin is creating a re=
distribution dilemma. There are 3 types of proposals:</span></p></li><ol st=
yle=3D"margin-top:0px;margin-bottom:0px"><li dir=3D"ltr" style=3D"list-styl=
e-type:lower-roman;font-size:11pt;font-family:&quot;Courier New&quot;,monos=
pace;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:nor=
mal;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;te=
xt-align:justify;margin-top:0pt;margin-bottom:0pt" role=3D"presentation"><s=
pan style=3D"font-size:11pt;background-color:transparent;font-variant-numer=
ic:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ver=
tical-align:baseline">Allow anyone to steal vulnerable coins, benefitting t=
hose who reach quantum capability earliest.</span></p></li><li dir=3D"ltr" =
style=3D"list-style-type:lower-roman;font-size:11pt;font-family:&quot;Couri=
er New&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-v=
ariant-numeric:normal;font-variant-east-asian:normal;font-variant-alternate=
s:normal;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;background-color:transparen=
t;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-a=
lternates:normal;vertical-align:baseline">Allow throttled theft of coins, w=
hich leads to RBF battles and ultimately miners subsidizing their revenue f=
rom lost coins.</span></p></li><li dir=3D"ltr" style=3D"list-style-type:low=
er-roman;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:base=
line;white-space:pre"><p dir=3D"ltr" style=3D"line-height:1.38;text-align:j=
ustify;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-ali=
gn:baseline">Allow no one to steal vulnerable coins.</span></p></li></ol></=
ol><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:transp=
arent;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:n=
ormal;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:0=
pt;margin-bottom:0pt" role=3D"presentation"><span style=3D"font-size:11pt;b=
ackground-color:transparent;font-variant-numeric:normal;font-variant-east-a=
sian:normal;font-variant-alternates:normal;vertical-align:baseline">Minimiz=
es attack surface</span></p></li><ol style=3D"margin-top:0px;margin-bottom:=
0px"><li dir=3D"ltr" style=3D"list-style-type:lower-alpha;font-size:11pt;fo=
nt-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-col=
or:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;f=
ont-variant-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;marg=
in-bottom:0pt" role=3D"presentation"><span style=3D"font-size:11pt;backgrou=
nd-color:transparent;font-variant-numeric:normal;font-variant-east-asian:no=
rmal;font-variant-alternates:normal;vertical-align:baseline">By disallowing=
 new spends to quantum vulnerable script types, we minimize the attack surf=
ace with each new UTXO.=C2=A0=C2=A0</span></p></li><li dir=3D"ltr" style=3D=
"list-style-type:lower-alpha;font-size:11pt;font-family:&quot;Courier New&q=
uot;,monospace;color:rgb(0,0,0);background-color:transparent;font-variant-n=
umeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal=
;vertical-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"presen=
tation"><span style=3D"font-size:11pt;background-color:transparent;font-var=
iant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:=
normal;vertical-align:baseline">Upgrades to Bitcoin have historically taken=
 many years; this will hasten and speed up the adoption of new quantum resi=
stant script types.=C2=A0</span></p></li><li dir=3D"ltr" style=3D"list-styl=
e-type:lower-alpha;font-size:11pt;font-family:&quot;Courier New&quot;,monos=
pace;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:nor=
mal;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;te=
xt-align:justify;margin-top:0pt;margin-bottom:0pt" role=3D"presentation"><s=
pan style=3D"font-size:11pt;background-color:transparent;font-variant-numer=
ic:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ver=
tical-align:baseline">With a clear deadline, industry stakeholders will mor=
e readily upgrade existing infrastructure to ensure continuity of services.=
=C2=A0=C2=A0</span></p></li></ol><li dir=3D"ltr" style=3D"list-style-type:d=
isc;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;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"presentation"><=
span style=3D"font-size:11pt;background-color:transparent;font-variant-nume=
ric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ve=
rtical-align:baseline">Minimizes loss of access to funds=C2=A0</span></p></=
li><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&qu=
ot;,monospace;color:rgb(0,0,0);background-color:transparent;font-variant-nu=
meric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;=
vertical-align:baseline;white-space:pre"><p dir=3D"ltr" style=3D"line-heigh=
t:1.38;text-align:justify;margin-top:0pt;margin-bottom:12pt" role=3D"presen=
tation"><span style=3D"font-size:11pt;background-color:transparent;font-var=
iant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:=
normal;vertical-align:baseline">If there is sufficient demand and research =
proves possible, submitting a ZK proof of knowledge of a BIP-39 seed phrase=
 corresponding to  a public key hash or script hash would provide a trustle=
ss means for legacy outputs to be spent in a quantum resistant manner, even=
 after the sunset.=C2=A0=C2=A0</span></p></li></ol></ul><br><div dir=3D"ltr=
" style=3D"margin-left:0pt" align=3D"left"><table style=3D"border:none;bord=
er-collapse:collapse"><colgroup><col width=3D"143"><col width=3D"539"></col=
group><tbody><tr style=3D"height:27.4463pt"><td style=3D"border-width:1pt;b=
order-style:solid;border-color:rgb(0,0,0);vertical-align:top;padding:5pt;ov=
erflow:hidden"><p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;marg=
in-bottom:0pt"><span style=3D"font-size:11pt;font-family:&quot;Courier New&=
quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-weight:7=
00;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-=
alternates:normal;vertical-align:baseline">Stakeholder</span></p></td><td s=
tyle=3D"border-width:1pt;border-style:solid;border-color:rgb(0,0,0);vertica=
l-align:top;padding:5pt;overflow:hidden"><p dir=3D"ltr" style=3D"line-heigh=
t:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"font-size:11pt;font=
-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color=
:transparent;font-weight:700;font-variant-numeric:normal;font-variant-east-=
asian:normal;font-variant-alternates:normal;vertical-align:baseline">Incent=
ive to Upgrade</span></p></td></tr><tr style=3D"height:53.5388pt"><td style=
=3D"border-width:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-al=
ign: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;,monospace;color:rgb(0,0,0);background-color:=
transparent;font-weight:700;font-variant-numeric:normal;font-variant-east-a=
sian:normal;font-variant-alternates:normal;vertical-align:baseline">Miners<=
/span></p></td><td style=3D"border-width:1pt;border-style:solid;border-colo=
r:rgb(0,0,0);vertical-align:top;padding:5pt;overflow:hidden"><p dir=3D"ltr"=
 style=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D=
"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0=
,0);background-color:transparent;font-variant-numeric:normal;font-variant-e=
ast-asian:normal;font-variant-alternates:normal;vertical-align:baseline">=
=E2=80=A2 Larger size PQ signatures along with incentive for users to migra=
te will create more demand for block space and thus higher fees collected b=
y 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);background-color:transparent;font-var=
iant-numeric:normal;font-variant-east-asian: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-bottom:0pt"><span style=3D"font-size:11pt;font-famil=
y:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:trans=
parent;font-variant-numeric:normal;font-variant-east-asian:normal;font-vari=
ant-alternates:normal;vertical-align:baseline">=E2=80=A2 A quantum attack o=
n Bitcoin will significantly devalue both their hardware and Bitcoin as a w=
hole.=C2=A0</span></p></td></tr><tr style=3D"height:52pt"><td style=3D"bord=
er-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;ma=
rgin-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:transpar=
ent;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:nor=
mal;font-variant-alternates:normal;vertical-align:baseline">Institutional H=
olders</span></p></td><td style=3D"border-width:1pt;border-style:solid;bord=
er-color:rgb(0,0,0);vertical-align:top;padding:5pt;overflow:hidden"><p dir=
=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span =
style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;color=
:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font-v=
ariant-east-asian:normal;font-variant-alternates:normal;vertical-align:base=
line">=E2=80=A2 Fiduciary duty: failing to act to prevent a quantum attack =
on Bitcoin would violate the fiduciary duty to shareholders.=C2=A0=C2=A0</s=
pan></p><p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-bott=
om:0pt"><span style=3D"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;verti=
cal-align:baseline">=E2=80=A2 Demonstrating Bitcoin=E2=80=99s ability to ef=
fectively mitigate emerging threats will prove Bitcoin to be an investment =
grade asset.</span></p></td></tr><tr style=3D"height:52pt"><td style=3D"bor=
der-width:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-align:mid=
dle;padding: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-family:=
&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transpa=
rent;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:no=
rmal;font-variant-alternates:normal;vertical-align:baseline">Exchanges &amp=
; Custodians</span></p></td><td style=3D"border-width:1pt;border-style:soli=
d;border-color:rgb(0,0,0);vertical-align:top;padding:5pt;overflow:hidden"><=
p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><=
span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;=
color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;f=
ont-variant-east-asian:normal;font-variant-alternates:normal;vertical-align=
:baseline">=E2=80=A2 Concentrated risk: a quantum hack could bankrupt them =
overnight.</span></p><p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0p=
t;margin-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-va=
riant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates=
:normal;vertical-align:baseline">=E2=80=A2 Early migration is cheap relativ=
e to potential losses, potential lawsuits over improper custody and reputat=
ional damage.</span></p></td></tr><tr style=3D"height:52pt"><td style=3D"bo=
rder-width: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:11pt;font-family=
:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transp=
arent;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:n=
ormal;font-variant-alternates:normal;vertical-align:baseline">Everyday User=
s</span></p></td><td style=3D"border-width:1pt;border-style:solid;border-co=
lor: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-variant-numeric:normal;font-varian=
t-east-asian:normal;font-variant-alternates:normal;vertical-align:baseline"=
>=E2=80=A2 Self-sovereign peace of mind.</span></p><p dir=3D"ltr" style=3D"=
line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"font-size=
:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);backgr=
ound-color:transparent;font-variant-numeric:normal;font-variant-east-asian:=
normal;font-variant-alternates:normal;vertical-align:baseline">=E2=80=A2 Su=
nset 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 procrasti=
nation.</span></p></td></tr><tr style=3D"height:43.7925pt"><td style=3D"bor=
der-width:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-align:mid=
dle;padding: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-family:=
&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transpa=
rent;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:no=
rmal;font-variant-alternates:normal;vertical-align:baseline">Attackers</spa=
n></p></td><td style=3D"border-width:1pt;border-style:solid;border-color:rg=
b(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"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">=E2=80=
=A2 Economic incentive diminishes as sunset nears, stolen coins cannot be s=
pent after Q-day.</span></p></td></tr></tbody></table></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;,mon=
ospace;color:rgb(0,0,0);background-color:transparent;font-weight:700;font-v=
ariant-numeric:normal;font-variant-east-asian:normal;font-variant-alternate=
s:normal;vertical-align:baseline">Key Insight:</span><span style=3D"font-si=
ze:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);back=
ground-color:transparent;font-variant-numeric:normal;font-variant-east-asia=
n:normal;font-variant-alternates:normal;vertical-align:baseline"> As mentio=
ned 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;vertic=
al-align:baseline">private incentive to upgrade</span><span style=3D"font-s=
ize:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);bac=
kground-color:transparent;font-variant-numeric:normal;font-variant-east-asi=
an:normal;font-variant-alternates:normal;vertical-align:baseline">.=C2=A0=
=C2=A0</span></p><p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;ma=
rgin-bottom:0pt"><span style=3D"font-size:11pt;font-family:&quot;Courier Ne=
w&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-varian=
t-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:nor=
mal;vertical-align:baseline">This is not an offensive attack, rather, it is=
 defensive: our thesis is that the Bitcoin ecosystem wishes to defend itsel=
f and its interests against those who would prefer to do nothing and allow =
a malicious actor to destroy both value and trust.=C2=A0=C2=A0</span></p><p=
 dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><s=
pan style=3D"background-color:transparent;color:rgb(0,0,0);font-family:&quo=
t;Courier New&quot;,monospace;font-size:11pt;text-align:center"><br></span>=
</p><blockquote style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb=
(204,204,204);padding-left:1ex" class=3D"gmail_quote"><span style=3D"backgr=
ound-color:transparent;color:rgb(0,0,0);font-family:&quot;Courier New&quot;=
,monospace;font-size:11pt;text-align:center">&quot;Lost coins only make eve=
ryone else&#39;s coins worth slightly more. Think of it as a donation to ev=
eryone.&quot; - Satoshi Nakamoto</span></blockquote><br><p dir=3D"ltr" styl=
e=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);b=
ackground-color:transparent;font-variant-numeric:normal;font-variant-east-a=
sian:normal;font-variant-alternates:normal;vertical-align:baseline">If true=
, the corollary is:</span></p><p dir=3D"ltr" style=3D"line-height:1.38;marg=
in-top:0pt;margin-bottom:0pt"><span style=3D"background-color:transparent;c=
olor:rgb(0,0,0);font-family:&quot;Courier New&quot;,monospace;font-size:11p=
t;text-align:center"><br></span></p><blockquote style=3D"margin:0px 0px 0px=
 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex" class=3D"gm=
ail_quote"><span style=3D"background-color:transparent;color:rgb(0,0,0);fon=
t-family:&quot;Courier New&quot;,monospace;font-size:11pt;text-align:center=
">&quot;Quantum recovered coins only make everyone else&#39;s coins worth l=
ess. Think of it as a theft from everyone.&quot;</span></blockquote><br><p =
dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><sp=
an style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;co=
lor:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;fon=
t-variant-east-asian:normal;font-variant-alternates:normal;vertical-align:b=
aseline">The timelines that we are proposing are meant to find the best bal=
ance between giving ample ability for account owners to migrate while maint=
aining the integrity of the overall ecosystem to avoid catastrophic attacks=
.=C2=A0=C2=A0</span></p><br><h2 dir=3D"ltr" style=3D"line-height:1.38;margi=
n-top:18pt;margin-bottom:4pt"><span style=3D"font-size:17pt;font-family:&qu=
ot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transparen=
t;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-a=
lternates:normal;vertical-align:baseline">Backward Compatibility</span></h2=
><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;,monospac=
e;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal=
;font-variant-east-asian:normal;font-variant-alternates:normal;vertical-ali=
gn:baseline">As a series of soft forks, older nodes will continue to operat=
e without modification. Non-upgraded nodes, however, will consider all post=
-quantum witness programs as anyone-can-spend scripts. They are strongly en=
couraged 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:0=
pt"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monos=
pace;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:nor=
mal;font-variant-east-asian:normal;font-variant-alternates:normal;vertical-=
align:baseline">Non-upgraded wallets can receive and send bitcoin from non-=
upgraded and upgraded wallets until Phase A. After Phase A, they can no lon=
ger receive from any other wallets and can only send to upgraded wallets.=
=C2=A0 After Phase B, both senders and receivers will require upgraded wall=
ets.=C2=A0Phase C would likely require a loosening of consensus rules (a ha=
rd fork) to allow vulnerable funds recovery via ZK proofs.</span></p></span=
></div>
</blockquote></div>

<p></p>

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