path: root/37/6871ab5341f27343e4e85b66d86ca373a5b857

Delivery-date: Sat, 12 Jul 2025 17:46:17 -0700
Received: from mail-yw1-f183.google.com ([209.85.128.183])
	by mail.fairlystable.org with esmtps  (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
	(Exim 4.94.2)
	(envelope-from <bitcoindev+bncBDFIP6H73EBBBTMDZTBQMGQEQA6MLTY@googlegroups.com>)
	id 1uakrA-0004yU-9u
	for bitcoindev@gnusha.org; Sat, 12 Jul 2025 17:46:17 -0700
Received: by mail-yw1-f183.google.com with SMTP id 00721157ae682-70e5ae5c517sf45598667b3.1
        for <bitcoindev@gnusha.org>; Sat, 12 Jul 2025 17:46:15 -0700 (PDT)
ARC-Seal: i=2; a=rsa-sha256; t=1752367570; cv=pass;
        d=google.com; s=arc-20240605;
        b=AmqAguq+6c0o1CLQf126ddQKtI75eFs4u0W0FznsHbw1Wo++mnYCLjMSIWE420W7BN
         EuJhQuopuGX4vbmfkzHsnIbXfKs1B8ATSCtWcctDxfjoUtvwJa2GEYOBZBB/JSgd9OQp
         iBE7Q41jke6r9MmvZax6bPduzjecflbTd8pD6C9VwzC4d6IqRv/QDTcaZdLMOG3mJyCz
         wsUWbhYpJbHynVM22p3D7OK+p/Rq6A2IQ4+PlBJmxaaMNjHtmo16RsN0W6SLX4Au2tmd
         1pcHBlQ0juAsmPZ6tCpjVg9tQEQPKBLdBl4BVzgK87SKbgPLLW+CUyLAjSrCXw9u4vl4
         NyGA==
ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20240605;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:to:subject:message-id:date:from
         :mime-version:sender:dkim-signature:dkim-signature;
        bh=UFc+IQplhBMSS9xd8yu/okXaTp//SbStDZDXn+0EagQ=;
        fh=nFlLCiSqz0eksuCH215gM5q4r0SvlrlQWMLNlgyiLLI=;
        b=JoBwUhf5sO9KrrUgicV+sh/fPxhefdv/j94Y2ddmyFsNU3Pg7FWeTVXC4cGOOpmwmd
         0CjGY5EJXHQ09d4v+aGqaMAIWi/Eo16QkSxLGmk3jCUTAmSmK5MKNX4sH3mT5KA+Kuxu
         jcTLgD/NiIJOFBL4rBnNesYX80SY88N/kYYldl6pjoIwoMfMOwYFmChRYdHHY9RnyFuu
         xC8nj+Njml1aZ61irzAI0PbEXuEnlv06JcqBMHcm0l9GzdWHYiN6C9kc0JmCARkD4uPm
         ABjEAleyNTB4BGL5NlLR+o3ed+dYS+a/htJxJhx7ir9EgfK1/2QoRe4+GsCUsgOYhM/d
         pmhg==;
        darn=gnusha.org
ARC-Authentication-Results: i=2; gmr-mx.google.com;
       dkim=pass header.i=@gmail.com header.s=20230601 header.b=TZUPqbHe;
       spf=pass (google.com: domain of jameson.lopp@gmail.com designates 2a00:1450:4864:20::22c as permitted sender) smtp.mailfrom=jameson.lopp@gmail.com;
       dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com;
       dara=pass header.i=@googlegroups.com
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=googlegroups.com; s=20230601; t=1752367570; x=1752972370; darn=gnusha.org;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:x-original-authentication-results
         :x-original-sender:to:subject:message-id:date:from:mime-version
         :sender:from:to:cc:subject:date:message-id:reply-to;
        bh=UFc+IQplhBMSS9xd8yu/okXaTp//SbStDZDXn+0EagQ=;
        b=WA2HbPmJJxSJz54TDjVWWt1Bj2KBwOgVDl0b9Yl9j2+24rFAKpU3pRjmAHNj+eK5Wt
         AMTnxl5KyWY3nbSCBJQSNnlBnCIXZcrJGTwm1PYnPhVBd5JyC6NZ1ZKPy8B2K+BNhPFD
         bGHxJUXI+IpT52XXNPKyTMqzi34dwfPOPqZuPCPUBi6fbgJxGXwtRNauY8gce+t0OoVA
         T7LpA9esXhKX6PsjHaLzAHzLDZpxfRnNZ+ahMM18g6Vqgke3kfMfLxWCOnT3r8G6SoSI
         dQ3gh8pNGO6asRa3NRtS2eLEDnjgZisSfy2gUNnIG4p9HR4cG3PI+Hidgya42lEZ7VFV
         keDg==
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20230601; t=1752367570; x=1752972370; darn=gnusha.org;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:x-original-authentication-results
         :x-original-sender:to:subject:message-id:date:from:mime-version:from
         :to:cc:subject:date:message-id:reply-to;
        bh=UFc+IQplhBMSS9xd8yu/okXaTp//SbStDZDXn+0EagQ=;
        b=OWs68vdo2V8QYwhNTfEIhfVPXEzvuTm4LJn5DvWL5m/FG2EZlTY/jq0B+rhDA4yRGc
         GchPruejldThsFwABU38tNfEhulr/fVSlSUDsvgwSocRVXLTOygmmmZwUgSYoE1m/qNM
         PkTuHp40eIX3WzQ7hQDhgU3++OFmK3MxaTGTRsCkwx/K0lH0QpZUHLmPvjNVfZal6w7C
         ZShzfHbO7ZIB5n4twiH+DfJi6tnJIub2WphFmTwMOpmrO6UyAGlUQvmdYtPzhyKFKx6S
         1pV92A8cPGm65IVWPtsCQH28j5WamZwuQqXOzFRpNyi0MhBAGUpCXukgyX+158Dnzf0/
         ed3g==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20230601; t=1752367570; x=1752972370;
        h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post
         :list-id:mailing-list:precedence:x-original-authentication-results
         :x-original-sender:to:subject:message-id:date:from:mime-version
         :x-beenthere:x-gm-message-state:sender:from:to:cc:subject:date
         :message-id:reply-to;
        bh=UFc+IQplhBMSS9xd8yu/okXaTp//SbStDZDXn+0EagQ=;
        b=eJfFNmqCPZbPsxyS9PSyeMtRdRYHwBTEyt47Wg0xA8CTe+hYxXm8tr7WMRlpTdzH21
         HwkvLZvXpztH+I/PSgmcpKoTCqiDunmhoaigyvFsHqyao90LJ3c1+dRa4U1T+JBSBZK0
         dnBZoQYr4E0u9RDTkk7Q05Gm9sfiw25O5vXx3Iev9ggoLnyKa7vYkoCTWclFMciIWtq0
         aQLbMWwSUbFa8acwZgTTrbJomIYq24i6+iMwm7L4iQ9h27ZxKxihyAozv0YxvNKbzHrb
         WA4h3xKXWXNAsq8L2YmOqbPnyQsdohbYEHjnAn1SbRwHtQwU8hD6kF8bhaRslw2anjsr
         ijpw==
Sender: bitcoindev@googlegroups.com
X-Forwarded-Encrypted: i=2; AJvYcCXI6E38qTfIdHVohRhTj0LtXPuAIeztIMoT/twBP9Ij70Ls6pWXiLYiJFZe2VhPyEo8sJMvDoYiWz0h@gnusha.org
X-Gm-Message-State: AOJu0YyodRBcTBvdprXicF2m2prNDijdZdQx2Iv5x1+6VHzR7Qt87AaP
	YhKO+HT7drm1HWPtKvaWmbh9MgzxAn9n99jjRz24J28tms6bIEnas1Qo
X-Google-Smtp-Source: AGHT+IFKQK0vPAINv3a46CKV8vKszAvdPGytHsKKgUWGFFTeGI57Ln84osXgHbcBLWcpU0SVoQi2+g==
X-Received: by 2002:a05:690c:6e05:b0:710:edf9:d93b with SMTP id 00721157ae682-717d78c06c4mr138764407b3.11.1752367569537;
        Sat, 12 Jul 2025 17:46:09 -0700 (PDT)
X-BeenThere: bitcoindev@googlegroups.com; h=AZMbMZc80G+voQJnwxz0n7UWQcXtskxJc0BchVaaY7qhW51m+Q==
Received: by 2002:a25:49c7:0:b0:e7d:cee1:1ba9 with SMTP id 3f1490d57ef6-e8b77943577ls3467740276.2.-pod-prod-08-us;
 Sat, 12 Jul 2025 17:46:05 -0700 (PDT)
X-Received: by 2002:a05:690c:968e:b0:711:41a5:482a with SMTP id 00721157ae682-717d7a19bf4mr141350377b3.27.1752367565284;
        Sat, 12 Jul 2025 17:46:05 -0700 (PDT)
Received: by 2002:a05:600c:1c1f:b0:456:53b:5b5e with SMTP id 5b1f17b1804b1-4561334fd09ms5e9;
        Sat, 12 Jul 2025 14:36:48 -0700 (PDT)
X-Received: by 2002:adf:b613:0:b0:3a4:eb92:b5eb with SMTP id ffacd0b85a97d-3b5f18f8be2mr6233258f8f.50.1752356205989;
        Sat, 12 Jul 2025 14:36:45 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1752356205; cv=none;
        d=google.com; s=arc-20240605;
        b=HUR6A03592GONxqSH98/+MVtm9kh9cWG8O5IDmlYuBn0rKWWhy5BhEcTZ7j7a3Y6oO
         L4w79tODnN5nSJD9/f2DCT8Hwjuaz4M4rlguvB/V4fN7U8Zb9iso78dI7MBHVxXE165S
         dTubvrR/m5bUy7uB5ZAmVdqhdp5moHScJeZCMCO2yRisfvQg6DSlqz3PZqJDgvUVEnCQ
         HaR/a7+k7poKVf7IDdY8gd/vEVTF51IRql+XX/2OIPoHQa7IkV9tsVs7ABmgNvEnFz2D
         JH+UL7wVvkzyVLmGeTuAsPsX9YuwsiMd1geasY7T33Nv8pFUt3x+xHbdyN7b5wPVeTq2
         V+ig==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20240605;
        h=to:subject:message-id:date:from:mime-version:dkim-signature;
        bh=eSdsWfQXGrssxAK9pfQH27X9Leb9gIenMLXpR+eXnQA=;
        fh=DMP0F9ULS1guKiqimntQRCN8ZraraesEgQuVcn7F0Z0=;
        b=g3TiOHYot3zOmU7Bmn9zPLD+3xcvsAqHSx1hetz7Dq6ZQ2y3MDHBgGMEm4JWm6Xwrq
         /1+CG1WOjqIVkuzbOnZbfDZBz7BdHJLJOkEXgx84GaAbqkgHYYk9geUxLwGjiqb0ixPl
         0/ElG/0coSIlbwh/HmcLPp5vst5FnzOZnu9isgTRtNP5R4QTYCzpGucxwhq3bJrN/qs6
         2aDgiN/En0uwTKOCRpJTmjztAaGcZ86PNcNn/sBEyz8z+6UhHXOTeM6bBTSxk0kn9V2m
         Cc/gbbu7ZTEEOJKQhGX+j1jFKu5iSlNwDKFcqO6wRmw3gLjKeI41jCBzedBgrVNN10Dy
         7n+Q==;
        dara=google.com
ARC-Authentication-Results: i=1; gmr-mx.google.com;
       dkim=pass header.i=@gmail.com header.s=20230601 header.b=TZUPqbHe;
       spf=pass (google.com: domain of jameson.lopp@gmail.com designates 2a00:1450:4864:20::22c as permitted sender) smtp.mailfrom=jameson.lopp@gmail.com;
       dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com;
       dara=pass header.i=@googlegroups.com
Received: from mail-lj1-x22c.google.com (mail-lj1-x22c.google.com. [2a00:1450:4864:20::22c])
        by gmr-mx.google.com with ESMTPS id ffacd0b85a97d-3b5e8dfa170si179682f8f.3.2025.07.12.14.36.45
        for <bitcoindev@googlegroups.com>
        (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128);
        Sat, 12 Jul 2025 14:36:45 -0700 (PDT)
Received-SPF: pass (google.com: domain of jameson.lopp@gmail.com designates 2a00:1450:4864:20::22c as permitted sender) client-ip=2a00:1450:4864:20::22c;
Received: by mail-lj1-x22c.google.com with SMTP id 38308e7fff4ca-32b3a3a8201so28719371fa.0
        for <bitcoindev@googlegroups.com>; Sat, 12 Jul 2025 14:36:45 -0700 (PDT)
X-Gm-Gg: ASbGncvV43xD9v1Fl+ujQf77mB3MOAwu6RQoUqVudtmHh73h50HEG9nHlnfGKywyAcA
	i7wZGNCKkq/eV7OkPOzX/9BEfl+FimqVANkeCuZoOKoM4LWBKkKE9wquX+B0xu0N6CKU8ch8VoQ
	Pel5vxCyiLf0lf+nAAe7Xxaam97tOiyE93s3Ui9mj/2dbCA0S71al7qUiHUtD80IWzLoFa2ObVr
	hc2EYCt
X-Received: by 2002:a2e:aa86:0:b0:32b:7ddd:275f with SMTP id
 38308e7fff4ca-3305343839emr18032711fa.30.1752356204197; Sat, 12 Jul 2025
 14:36:44 -0700 (PDT)
MIME-Version: 1.0
From: Jameson Lopp <jameson.lopp@gmail.com>
Date: Sat, 12 Jul 2025 17:36:31 -0400
X-Gm-Features: Ac12FXyc1cw6eTJyBWxaO3hn5Wl6z9LIk34KAiZ_Ku2EghjeTne1_DHbp3XMxFo
Message-ID: <CADL_X_fpv-aXBxX+eJ_EVTirkAJGyPRUNqOCYdz5um8zu6ma5Q@mail.gmail.com>
Subject: [bitcoindev] A Post Quantum Migration Proposal
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Content-Type: multipart/alternative; boundary="000000000000123e1d0639c239f9"
X-Original-Sender: jameson.lopp@gmail.com
X-Original-Authentication-Results: gmr-mx.google.com;       dkim=pass
 header.i=@gmail.com header.s=20230601 header.b=TZUPqbHe;       spf=pass
 (google.com: domain of jameson.lopp@gmail.com designates 2a00:1450:4864:20::22c
 as permitted sender) smtp.mailfrom=jameson.lopp@gmail.com;       dmarc=pass
 (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com;       dara=pass header.i=@googlegroups.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 (/)

--000000000000123e1d0639c239f9
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

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

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 *after* consensus is established that it is prudent to
do so.

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

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

   -

   Phase A: Disallows sending of any funds to quantum-vulnerable addresses,
   hastening the adoption of P2QRH address types.
   -

   Phase B: Renders ECDSA/Schnorr spends invalid, preventing all spending
   of funds in quantum-vulnerable UTXOs. This is triggered by a
   well-publicized flag-day roughly five years after activation.
   -

   Phase C (optional): Pending further research and demand, a separate BIP
   proposing a fork to allow recovery of legacy UTXOs through ZK proof of
   possession of BIP-39 seed phrase.

Motivation

We seek to secure the value of the UTXO set and minimize incentives for
quantum 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.  Never before=
 has
Bitcoin faced an existential threat to its cryptographic primitives. A
successful quantum attack on Bitcoin would result in significant economic
disruption and damage across the entire ecosystem. Beyond its impact on
price, the ability of miners to provide network security may be
significantly impacted.

   -

   Accelerating quantum progress.
   -

      NIST ratified three production-grade PQ signature schemes in 2024;
      academic road-maps now estimate a cryptographically-relevant quantum
      computer as early as 2027-2030. [McKinsey
      <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>
      ]
      -

   Quantum algorithms are rapidly improving
   -

      The safety envelope is shrinking by dramatic increases in algorithms
      even if the pace of hardware improvements is slower. Algorithms
are improving
      up to 20X
      <https://security.googleblog.com/2025/05/tracking-cost-of-quantum-fac=
tori.html>,
      lowering the theoretical hardware requirements for breaking classical
      encryption.
      -

   Bitcoin=E2=80=99s exposed public keys.
   -

      Roughly 25% of all bitcoin have revealed a public key on-chain; those
      UTXOs could be stolen with sufficient quantum power.
      -

   We may not know the attack is underway.
   -

      Quantum attackers could compute the private key for known public keys
      then transfer all funds weeks or months later, in a covert bleed to n=
ot
      alert chain watchers. Q-Day may be only known much later if the attac=
k
      withholds broadcasting transactions in order to postpone revealing th=
eir
      capabilities.
      -

   Private keys become public.
   -

      Assuming that quantum computers are able to maintain their current
      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.
      -

   Impossible to know motivations.
   -

      Prior to a quantum attack, it is impossible to know the motivations
      of the attacker.  An economically motivated attacker will try to rema=
in
      undetected for as long as possible, while a malicious attacker
will attempt
      to destroy as much value as possible.
      -

   Upgrade inertia.
   -

      Coordinating wallets, exchanges, miners and custodians historically
      takes years.
      -

      The longer we postpone migration, the harder it becomes to coordinate
      wallets, exchanges, miners, and custodians. A clear, time-boxed
pathway is
      the only credible defense.
      -

      Coordinating distributed groups is more prone to delay, even if
      everyone has similar motivations. Historically, Bitcoin has been slow=
 to
      adopt code changes, often taking multiple years to be approved.

Benefits at a Glance

   -

   Resilience: Bitcoin protocol remains secure for the foreseeable future
   without waiting for a last-minute emergency.
   -

   Certainty: Bitcoin users and stakeholders gain certainty that a plan is
   both in place and being implemented to effectively deal with the threat =
of
   quantum theft of bitcoin.
   -

   Clarity: A single, publicized timeline aligns the entire ecosystem
   (wallets, exchanges, hardware vendors).
   -

   Supply Discipline: Abandoned keys that never migrate become unspendable,
   reducing supply, as Satoshi described
   <https://bitcointalk.org/index.php?topic=3D198.msg1647#msg1647>.

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
ECDSA/Schnorr keys.

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
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

   -

   Even if Bitcoin is not a primary initial target of a cryptographically
   relevant quantum computer, widespread knowledge that such a computer exi=
sts
   and is capable of breaking Bitcoin=E2=80=99s cryptography will damage fa=
ith in the
   network .
   -

   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.  There is no way to know=
 in
   advance how, when, or why an attack may occur.  A defensive position mus=
t
   be taken well in advance of any attack.
   -

   Bitcoin=E2=80=99s current signatures (ECDSA/Schnorr) will be a tantalizi=
ng
   target: any UTXO that has ever exposed its public key on-chain (roughly =
25
   % of all bitcoin) could be stolen by a cryptographically relevant quantu=
m
   computer.
   -

   Existing Proposals are Insufficient.
   1.

      Any proposal that allows for the quantum theft of =E2=80=9Clost=E2=80=
=9D bitcoin is
      creating a redistribution dilemma. There are 3 types of proposals:
      1.

         Allow anyone to steal vulnerable coins, benefitting those who
         reach quantum capability earliest.
         2.

         Allow throttled theft of coins, which leads to RBF battles and
         ultimately miners subsidizing their revenue from lost coins.
         3.

         Allow no one to steal vulnerable coins.
         -

   Minimizes attack surface
   1.

      By disallowing new spends to quantum vulnerable script types, we
      minimize the attack surface with each new UTXO.
      2.

      Upgrades to Bitcoin have historically taken many years; this will
      hasten and speed up the adoption of new quantum resistant script type=
s.
      3.

      With a clear deadline, industry stakeholders will more readily
      upgrade existing infrastructure to ensure continuity of services.
      -

   Minimizes loss of access to funds
   1.

      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 trustless means
for legacy
      outputs to be spent in a quantum resistant manner, even after
the sunset.


Stakeholder

Incentive to Upgrade

Miners

=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 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
hardware and Bitcoin as a whole.

Institutional Holders

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

=E2=80=A2 Demonstrating Bitcoin=E2=80=99s ability to effectively mitigate e=
merging threats
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
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
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
spent after Q-day.

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

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


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


If true, the corollary is:


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


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

Backward Compatibility

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 strongly encouraged
to upgrade in order to fully validate the new programs.

Non-upgraded wallets can receive and send bitcoin from non-upgraded and
upgraded wallets until Phase A. After Phase A, they can no longer receive
from any other wallets and can only send to upgraded wallets.  After Phase
B, both senders and receivers will require upgraded wallets. Phase C would
likely require a loosening of consensus rules (a hard fork) to allow
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/=
CADL_X_fpv-aXBxX%2BeJ_EVTirkAJGyPRUNqOCYdz5um8zu6ma5Q%40mail.gmail.com.

--000000000000123e1d0639c239f9
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><span id=3D"gmail-docs-internal-guid-5ad3cb7f-7fff-eaec-9e=
e0-841259198a5c"><p dir=3D"ltr" style=3D"line-height:1.44;background-color:=
rgb(255,255,255);margin-top:12pt;margin-bottom:0pt;padding:0pt 0pt 12pt"><s=
pan style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;c=
olor:rgb(34,34,34);background-color:transparent;font-weight:400;font-style:=
normal;font-variant:normal;text-decoration:none;vertical-align:baseline;whi=
te-space:pre-wrap">Building upon my earlier essay </span><a href=3D"https:/=
/groups.google.com/g/bitcoindev/c/uUK6py0Yjq0/m/6peEaa90AQAJ" style=3D"text=
-decoration:none"><span style=3D"font-size:11pt;font-family:&quot;Courier N=
ew&quot;,monospace;color:rgb(17,85,204);background-color:transparent;font-w=
eight:400;font-style:normal;font-variant:normal;text-decoration:underline;v=
ertical-align:baseline;white-space:pre-wrap">against allowing quantum recov=
ery of bitcoin</span></a><span style=3D"font-size:11pt;font-family:&quot;Co=
urier New&quot;,monospace;color:rgb(34,34,34);background-color:transparent;=
font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;=
vertical-align:baseline;white-space:pre-wrap"> I wish to formalize a propos=
al after several months of discussions.</span></p><p dir=3D"ltr" style=3D"l=
ine-height:1.44;background-color:rgb(255,255,255);margin-top:0pt;margin-bot=
tom:0pt;padding:0pt 0pt 12pt"><span style=3D"font-size:11pt;font-family:&qu=
ot;Courier New&quot;,monospace;color:rgb(34,34,34);background-color:transpa=
rent;font-weight:400;font-style:normal;font-variant:normal;text-decoration:=
none;vertical-align:baseline;white-space:pre-wrap">This proposal does not d=
elve into the multitude of issues regarding post quantum cryptography and t=
rade-offs of different schemes, but rather is meant to specifically address=
 the issues of incentivizing adoption and migration of funds </span><span s=
tyle=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;color:=
rgb(34,34,34);background-color:transparent;font-weight:400;font-variant:nor=
mal;text-decoration:none;vertical-align:baseline;white-space:pre-wrap"><i>a=
fter</i></span><span style=3D"font-size:11pt;font-family:&quot;Courier New&=
quot;,monospace;color:rgb(34,34,34);background-color:transparent;font-weigh=
t:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-a=
lign:baseline;white-space:pre-wrap"> consensus is established that it is pr=
udent to do so.</span></p><p dir=3D"ltr" style=3D"line-height:1.44;backgrou=
nd-color:rgb(255,255,255);margin-top:0pt;margin-bottom:12pt"><span style=3D=
"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0=
,0);background-color:transparent;font-weight:400;font-style:normal;font-var=
iant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wr=
ap">As such, this proposal requires P2QRH as described in BIP-360 or potent=
ial future proposals.</span></p><h2 dir=3D"ltr" style=3D"line-height:1.38;m=
argin-top:18pt;margin-bottom:4pt"><span style=3D"font-size:17pt;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">Abstract</span></h2><p dir=3D=
"ltr" style=3D"line-height:1.38;margin-top:12pt;margin-bottom:12pt"><span s=
tyle=3D"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">This proposal follows the implementation of post-quantum (PQ) output t=
ype (P2QRH) and introduces a pre-announced sunset of legacy ECDSA/Schnorr s=
ignatures. It turns quantum security into a </span><span style=3D"font-size=
:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);backgr=
ound-color:transparent;font-style:italic;font-variant-numeric:normal;font-v=
ariant-east-asian:normal;font-variant-alternates:normal;vertical-align:base=
line">private incentive</span><span style=3D"font-size:11pt;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">: fail to upgrade and you will ce=
rtainly lose access to your funds, creating a certainty where none previous=
ly 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:&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;white-space:pre"><p dir=3D"ltr" s=
tyle=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt" role=3D"presenta=
tion"><span style=3D"font-size:11pt;background-color:transparent;font-weigh=
t:700;font-variant-numeric:normal;font-variant-east-asian:normal;font-varia=
nt-alternates:normal;vertical-align:baseline">Phase A:</span><span style=3D=
"font-size:11pt;background-color:transparent;font-variant-numeric:normal;fo=
nt-variant-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"lt=
r" style=3D"list-style-type:disc;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;margin-top:0pt;margin-bottom:0pt" role=3D"presentation"><span s=
tyle=3D"font-size:11pt;background-color:transparent;font-weight:700;font-va=
riant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates=
:normal;vertical-align:baseline">Phase B:</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"> Re=
nders ECDSA/Schnorr spends invalid, preventing all spending of funds in qua=
ntum-vulnerable UTXOs. This is triggered by a well-publicized flag-day roug=
hly five years after activation.</span></p></li><li dir=3D"ltr" style=3D"li=
st-style-type:disc;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;ma=
rgin-top:0pt;margin-bottom:6pt" role=3D"presentation"><span style=3D"font-s=
ize:11pt;background-color:transparent;font-weight:700;font-variant-numeric:=
normal;font-variant-east-asian:normal;font-variant-alternates:normal;vertic=
al-align:baseline">Phase C (optional):</span><span style=3D"font-size:11pt;=
background-color:transparent;font-variant-numeric:normal;font-variant-east-=
asian:normal;font-variant-alternates:normal;vertical-align:baseline"> Pendi=
ng further research and demand, a separate BIP proposing a fork to allow re=
covery of legacy UTXOs through 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;margin-top:14pt;margin-bottom:6pt"><span style=3D"font-=
size:16pt;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">Motivati=
on</span></h2><p dir=3D"ltr" style=3D"line-height:1.38;text-align:justify;m=
argin-top:12pt;margin-bottom:12pt"><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">We seek to secure the value =
of the UTXO set</span><span style=3D"font-size:11pt;font-family:&quot;Couri=
er New&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-w=
eight:700;font-variant-numeric:normal;font-variant-east-asian:normal;font-v=
ariant-alternates:normal;vertical-align:baseline"> </span><span style=3D"fo=
nt-size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0)=
;background-color:transparent;font-variant-numeric:normal;font-variant-east=
-asian:normal;font-variant-alternates:normal;vertical-align:baseline">and m=
inimize incentives for quantum attacks. This proposal is radically differen=
t 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=99=
s history.=C2=A0 Never before has Bitcoin faced an existential threat to it=
s cryptographic primitives. A successful quantum attack on Bitcoin would re=
sult in significant economic disruption and damage across the entire ecosys=
tem. Beyond its impact on price, the ability of miners to provide network s=
ecurity may be significantly impacted.=C2=A0=C2=A0</span></p><ul style=3D"m=
argin-top:0px;margin-bottom:0px"><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-variant-numeric:normal;font-varian=
t-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;m=
argin-bottom:0pt" role=3D"presentation"><span style=3D"font-size:11pt;backg=
round-color:transparent;font-weight:700;font-variant-numeric:normal;font-va=
riant-east-asian:normal;font-variant-alternates:normal;vertical-align:basel=
ine">Accelerating quantum progress.</span><span style=3D"font-size:11pt;bac=
kground-color:transparent;font-variant-numeric:normal;font-variant-east-asi=
an:normal;font-variant-alternates:normal;vertical-align:baseline">=C2=A0</s=
pan></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 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;margin-top:0pt;margin-bottom:0pt" role=3D"presentation"><span s=
tyle=3D"font-size:11pt;background-color:transparent;font-variant-numeric:no=
rmal;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 quant=
um computer as early as 2027-2030. [</span><a href=3D"https://www.mckinsey.=
com/~/media/mckinsey/business%20functions/mckinsey%20digital/our%20insights=
/the%20year%20of%20quantum%20from%20concept%20to%20reality%20in%202025/quan=
tum-monitor-2025.pdf?shouldIndex=3Dfalse" style=3D"text-decoration-line:non=
e"><span style=3D"font-size:11pt;background-color:transparent;font-variant-=
numeric:normal;font-variant-east-asian:normal;font-variant-alternates:norma=
l;text-decoration-line:underline;vertical-align:baseline">McKinsey</span></=
a><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">]</span></p></li></ul><li dir=3D"ltr" style=3D"li=
st-style-type:disc;font-size:11pt;font-family:&quot;Courier New&quot;,monos=
pace;color:rgb(0,0,0);background-color:transparent;font-weight:700;font-var=
iant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:=
normal;vertical-align:baseline;white-space:pre"><p dir=3D"ltr" style=3D"lin=
e-height:1.38;text-align:justify;margin-top:0pt;margin-bottom:0pt" role=3D"=
presentation"><span style=3D"font-size:11pt;background-color:transparent;fo=
nt-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alter=
nates:normal;vertical-align:baseline">Quantum algorithms are rapidly improv=
ing</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;text-align:justify;margin-top:0pt;margin-bottom:0pt" r=
ole=3D"presentation"><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">The safety envelope is shrinki=
ng by dramatic increases in algorithms even if the pace of hardware improve=
ments is slower. Algorithms are <a href=3D"https://security.googleblog.com/=
2025/05/tracking-cost-of-quantum-factori.html">improving up to 20X</a>, low=
ering the theoretical hardware requirements for breaking classical encrypti=
on.</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);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:0pt" 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">Bitco=
in=E2=80=99s exposed public keys.</span><span style=3D"font-size:11pt;backg=
round-color:transparent;font-variant-numeric:normal;font-variant-east-asian=
:normal;font-variant-alternates:normal;vertical-align:baseline">=C2=A0</spa=
n></p></li><ul style=3D"margin-top:0px;margin-bottom:0px"><li dir=3D"ltr" s=
tyle=3D"list-style-type:circle;font-size:11pt;font-family:&quot;Courier New=
&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-variant=
-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:norm=
al;vertical-align:baseline;white-space:pre"><p dir=3D"ltr" style=3D"line-he=
ight:1.38;margin-top:0pt;margin-bottom:0pt" role=3D"presentation"><span sty=
le=3D"font-size:11pt;background-color:transparent;font-variant-numeric:norm=
al;font-variant-east-asian:normal;font-variant-alternates:normal;vertical-a=
lign:baseline">Roughly 25% of all bitcoin have revealed a public key on-cha=
in; those 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;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-weight:700;font-variant-numeric:normal;fo=
nt-variant-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-st=
yle-type:circle;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;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-east-asian:normal;font-variant-alternates:normal;vertic=
al-align:baseline">Quantum attackers could compute the private key for know=
n public keys then transfer all funds weeks or months later, in a covert bl=
eed to not alert chain watchers. Q-Day may be only known much later if the =
attack withholds broadcasting transactions in order to postpone revealing t=
heir capabilities.</span></p></li></ul><li dir=3D"ltr" style=3D"list-style-=
type:disc;font-size:11pt;font-family:&quot;Courier New&quot;,monospace;colo=
r:rgb(0,0,0);background-color:transparent;font-weight:700;font-variant-nume=
ric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ve=
rtical-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;fo=
nt-variant-east-asian:normal;font-variant-alternates:normal;vertical-align:=
baseline">Private keys become public.=C2=A0</span></p></li><ul style=3D"mar=
gin-top:0px;margin-bottom:0px"><li dir=3D"ltr" style=3D"list-style-type:cir=
cle;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-weight:400;font-variant-numeric=
:normal;font-variant-east-asian:normal;font-variant-alternates:normal;verti=
cal-align:baseline">Assuming that quantum computers are able to maintain th=
eir current trajectories and overcome existing engineering obstacles, there=
 is a near certain chance that all P2PK (and other outputs with exposed pub=
keys) private keys will be found and used to steal the funds.</span></p></l=
i></ul><li dir=3D"ltr" style=3D"list-style-type:disc;font-size:11pt;font-fa=
mily:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:tr=
ansparent;font-weight:700;font-variant-numeric:normal;font-variant-east-asi=
an:normal;font-variant-alternates:normal;vertical-align:baseline;white-spac=
e:pre"><p dir=3D"ltr" style=3D"line-height:1.38;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">Impossible to know mot=
ivations.=C2=A0</span></p></li><ul style=3D"margin-top:0px;margin-bottom:0p=
x"><li dir=3D"ltr" style=3D"list-style-type:circle;font-size:11pt;font-fami=
ly:&quot;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;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:t=
ransparent;font-weight:400;font-variant-numeric:normal;font-variant-east-as=
ian:normal;font-variant-alternates:normal;vertical-align:baseline">Prior to=
 a quantum attack, it is impossible to know the motivations of the attacker=
.=C2=A0 An economically motivated attacker will try to remain undetected fo=
r as long as possible, while a malicious attacker will attempt to destroy a=
s much value as possible.=C2=A0=C2=A0</span></p></li></ul><li dir=3D"ltr" s=
tyle=3D"list-style-type:disc;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;margin-top:0pt;margin-bottom:0pt" role=3D"presentation"><span style=
=3D"font-size:11pt;background-color:transparent;font-weight:700;font-varian=
t-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:nor=
mal;vertical-align:baseline">Upgrade inertia.</span><span style=3D"font-siz=
e:11pt;background-color:transparent;font-variant-numeric:normal;font-varian=
t-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 d=
ir=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-alt=
ernates:normal;vertical-align:baseline;white-space:pre"><p dir=3D"ltr" styl=
e=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt" role=3D"presentatio=
n"><span style=3D"font-size:11pt;background-color:transparent;font-variant-=
numeric:normal;font-variant-east-asian:normal;font-variant-alternates:norma=
l;vertical-align:baseline">Coordinating wallets, exchanges, miners and cust=
odians historically takes years.</span></p></li><li dir=3D"ltr" style=3D"li=
st-style-type:circle;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;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-num=
eric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;v=
ertical-align:baseline">The longer we postpone migration, the harder it bec=
omes to coordinate wallets, exchanges, miners, and custodians. A clear, tim=
e-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 =
New&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-vari=
ant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:n=
ormal;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"=
presentation"><span style=3D"font-size:11pt;background-color:transparent;fo=
nt-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alter=
nates:normal;vertical-align:baseline">Coordinating distributed groups is mo=
re prone to delay, even if everyone has similar motivations. Historically, =
Bitcoin 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"=
font-size:16pt;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">Ben=
efits 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:A=
rial,sans-serif;color:rgb(0,0,0);background-color:transparent;font-variant-=
numeric:normal;font-variant-east-asian:normal;font-variant-alternates:norma=
l;vertical-align:baseline;white-space:pre"><p dir=3D"ltr" style=3D"line-hei=
ght:1.38;text-align:justify;margin-top:12pt;margin-bottom:0pt" role=3D"pres=
entation"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;=
,monospace;background-color:transparent;font-weight:700;font-variant-numeri=
c:normal;font-variant-east-asian:normal;font-variant-alternates:normal;vert=
ical-align:baseline">Resilience:</span><span style=3D"font-size:11pt;font-f=
amily:&quot;Courier New&quot;,monospace;background-color:transparent;font-v=
ariant-numeric:normal;font-variant-east-asian:normal;font-variant-alternate=
s:normal;vertical-align:baseline"> Bitcoin protocol remains secure for the =
foreseeable 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-famil=
y:Arial,sans-serif;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:0pt" role=3D"pr=
esentation"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quo=
t;,monospace;background-color:transparent;font-weight:700;font-variant-nume=
ric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;ve=
rtical-align:baseline">Certainty</span><span style=3D"font-size:11pt;font-f=
amily:&quot;Courier New&quot;,monospace;background-color:transparent;font-v=
ariant-numeric:normal;font-variant-east-asian:normal;font-variant-alternate=
s:normal;vertical-align:baseline">: Bitcoin users and stakeholders gain cer=
tainty that a plan is both in place and being implemented to effectively de=
al 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: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:0pt;margin-bottom:0pt" role=3D"presen=
tation"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,m=
onospace;background-color:transparent;font-weight:700;font-variant-numeric:=
normal;font-variant-east-asian:normal;font-variant-alternates:normal;vertic=
al-align:baseline">Clarity:</span><span style=3D"font-size:11pt;font-family=
:&quot;Courier New&quot;,monospace;background-color:transparent;font-varian=
t-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:nor=
mal;vertical-align:baseline"> A single, publicized timeline aligns the enti=
re 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">as Satoshi described</a></span><span style=3D"=
font-size:11pt;font-family:&quot;Courier New&quot;,monospace;background-col=
or:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;f=
ont-variant-alternates:normal;vertical-align:baseline">.=C2=A0=C2=A0</span>=
</p></li></ul><h2 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-fami=
ly:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:tran=
sparent;font-variant-numeric:normal;font-variant-east-asian:normal;font-var=
iant-alternates:normal;vertical-align:baseline">Specification</span></h2><h=
2 dir=3D"ltr" style=3D"line-height:1.38;text-align:justify;margin-top:12pt;=
margin-bottom:12pt"><span style=3D"font-weight:normal" id=3D"gmail-docs-int=
ernal-guid-4cbd2b46-7fff-d44c-45ec-e5d20a70bc82"><div dir=3D"ltr" style=3D"=
margin-left:0pt" align=3D"left"><table style=3D"border:none;border-collapse=
:collapse"><colgroup><col width=3D"181"><col width=3D"224"><col width=3D"13=
7"><col width=3D"130"></colgroup><tbody><tr style=3D"height:0pt"><td style=
=3D"border-width:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-al=
ign:top;padding:5pt;overflow:hidden"><p dir=3D"ltr" style=3D"line-height:1.=
38;text-align:center;margin-top:0pt;margin-bottom:0pt"><span style=3D"font-=
size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);ba=
ckground-color:transparent;font-weight:700;font-variant-numeric:normal;font=
-variant-east-asian:normal;font-variant-alternates:normal;vertical-align:ba=
seline">Phase</span></p></td><td style=3D"border-width:1pt;border-style:sol=
id;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;m=
argin-bottom:0pt"><span style=3D"font-size:11pt;font-family:&quot;Courier N=
ew&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-weigh=
t:700;font-variant-numeric:normal;font-variant-east-asian:normal;font-varia=
nt-alternates:normal;vertical-align:baseline">What Happens</span></p></td><=
td style=3D"border-width:1pt;border-style:solid;border-color:rgb(0,0,0);ver=
tical-align:top;padding:5pt;overflow:hidden"><p dir=3D"ltr" style=3D"line-h=
eight:1.38;text-align:center;margin-top:0pt;margin-bottom:0pt"><span style=
=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(=
0,0,0);background-color:transparent;font-weight:700;font-variant-numeric:no=
rmal;font-variant-east-asian:normal;font-variant-alternates:normal;vertical=
-align:baseline">Who Must Act</span></p></td><td style=3D"border-width:1pt;=
border-style:solid;border-color:rgb(0,0,0);vertical-align:top;padding:5pt;o=
verflow: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:transp=
arent;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:n=
ormal;font-variant-alternates:normal;vertical-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;o=
verflow: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;Courier New=
&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-weight:=
700;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant=
-alternates:normal;vertical-align:baseline">Phase A - </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-e=
ast-asian:normal;font-variant-alternates:normal;vertical-align:baseline">Di=
sallow spends to legacy script types</span></p></td><td style=3D"border-wid=
th:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-align:middle;pad=
ding:5pt;overflow:hidden"><p dir=3D"ltr" style=3D"line-height:1.38;margin-t=
op:0pt;margin-bottom:0pt"><span style=3D"font-size:10pt;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">Permitted sends are from legacy scrip=
ts to P2QRH scripts</span></p></td><td style=3D"border-width:1pt;border-sty=
le: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-bot=
tom: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;f=
ont-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alte=
rnates:normal;vertical-align:baseline">Everyone</span><span style=3D"font-s=
ize:10pt;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"> holding =
or accepting BTC.</span></p></td><td style=3D"border-width:1pt;border-style=
:solid;border-color:rgb(0,0,0);vertical-align:middle;padding:5pt;overflow:h=
idden"><p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-botto=
m: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-numeric:=
normal;font-variant-east-asian:normal;font-variant-alternates:normal;vertic=
al-align:baseline">3 years after BIP-360 implementation</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"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-weight:700;font-variant-nu=
meric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;=
vertical-align:baseline">Phase B =E2=80=93 </span><span style=3D"font-size:=
11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);backgro=
und-color:transparent;font-variant-numeric:normal;font-variant-east-asian:n=
ormal;font-variant-alternates:normal;vertical-align:baseline">Disallow spen=
ds 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;paddi=
ng: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;Cou=
rier New&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font=
-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alterna=
tes:normal;vertical-align:baseline">At a preset block-height, nodes reject =
transactions that rely on ECDSA/Schnorr keys.=C2=A0</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">2 years after Phase A a=
ctivation.</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;pa=
dding: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;f=
ont-weight:700;font-variant-numeric:normal;font-variant-east-asian:normal;f=
ont-variant-alternates:normal;vertical-align:baseline">Phase C =E2=80=93 </=
span><span style=3D"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">Re-enable spends from quantum vulnerable outputs via ZK Pr=
oof</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);background-color:transparent;font-variant-numeric:normal;font-v=
ariant-east-asian:normal;font-variant-alternates:normal;vertical-align:base=
line">Users with frozen quantum vulnerable funds and a HD wallet seed phras=
e can construct a quantum safe ZK proof to recover funds.</span></p></td><t=
d style=3D"border-width:1pt;border-style:solid;border-color:rgb(0,0,0);vert=
ical-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:10p=
t;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background=
-color:transparent;font-variant-numeric:normal;font-variant-east-asian:norm=
al;font-variant-alternates:normal;vertical-align: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;paddin=
g: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;Cour=
ier New&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-=
variant-numeric:normal;font-variant-east-asian:normal;font-variant-alternat=
es:normal;vertical-align:baseline">TBD pending research, demand, and consen=
sus.</span></p></td></tr></tbody></table></div></span></h2><h2 dir=3D"ltr" =
style=3D"line-height:1.38;margin-top:14pt;margin-bottom:6pt"><span style=3D=
"font-size:16pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0=
,0);background-color:transparent;font-weight:700;font-style:normal;font-var=
iant:normal;text-decoration:none;vertical-align:baseline;white-space:pre-wr=
ap">Rationale</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:&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;white-space:pre"><p dir=3D"ltr" styl=
e=3D"line-height:1.38;text-align:justify;margin-top:12pt;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">Even if Bitcoin is not a pri=
mary initial target of a cryptographically relevant quantum computer, wides=
pread knowledge that such a computer exists and is capable of breaking Bitc=
oin=E2=80=99s cryptography will damage faith in the network .=C2=A0</span><=
/p></li><li dir=3D"ltr" style=3D"list-style-type:disc;font-size:11pt;font-f=
amily:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:t=
ransparent;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=
-color:transparent;font-variant-numeric:normal;font-variant-east-asian:norm=
al;font-variant-alternates:normal;vertical-align:baseline">An attack on Bit=
coin 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, w=
hen, or why an attack may occur.=C2=A0 A defensive position must be taken w=
ell in advance of any attack.=C2=A0=C2=A0</span></p></li><li dir=3D"ltr" st=
yle=3D"list-style-type:disc;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:0pt" role=3D"present=
ation"><span style=3D"font-size:11pt;background-color:transparent;font-vari=
ant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:n=
ormal;vertical-align:baseline">Bitcoin=E2=80=99s current signatures (ECDSA/=
Schnorr) will be a tantalizing target: any UTXO that has ever exposed its p=
ublic key on-chain (roughly 25 % of all bitcoin) could be stolen by a crypt=
ographically relevant quantum computer.</span></p></li><li dir=3D"ltr" styl=
e=3D"list-style-type:disc;font-size:11pt;font-family:Arial,sans-serif;color=
:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font-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;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;vertical-align:baseline">=
Existing Proposals are Insufficient.</span><span style=3D"font-size:11pt;fo=
nt-family:&quot;Courier New&quot;,monospace;background-color:transparent;fo=
nt-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alter=
nates: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-t=
ype:lower-alpha;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;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-east-asian:normal;font-variant-alternates:normal;vertic=
al-align:baseline">Any proposal that allows for the quantum theft of =E2=80=
=9Clost=E2=80=9D bitcoin is creating a redistribution dilemma. There are 3 =
types of proposals:</span></p></li><ol style=3D"margin-top:0px;margin-botto=
m:0px"><li dir=3D"ltr" style=3D"list-style-type:lower-roman;font-size:11pt;=
font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-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;text-align:justify;margin-top:0pt;ma=
rgin-bottom:0pt" role=3D"presentation"><span style=3D"font-size:11pt;backgr=
ound-color:transparent;font-variant-numeric:normal;font-variant-east-asian:=
normal;font-variant-alternates:normal;vertical-align:baseline">Allow anyone=
 to steal vulnerable coins, benefitting those who reach quantum capability =
earliest.</span></p></li><li dir=3D"ltr" style=3D"list-style-type:lower-rom=
an;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;w=
hite-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"fon=
t-size:11pt;background-color:transparent;font-variant-numeric:normal;font-v=
ariant-east-asian:normal;font-variant-alternates:normal;vertical-align:base=
line">Allow throttled theft of coins, which leads to RBF battles and ultima=
tely miners subsidizing their revenue from lost coins.</span></p></li><li d=
ir=3D"ltr" style=3D"list-style-type:lower-roman;font-size:11pt;font-family:=
&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:transpa=
rent;font-variant-numeric:normal;font-variant-east-asian:normal;font-varian=
t-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:t=
ransparent;font-variant-numeric:normal;font-variant-east-asian:normal;font-=
variant-alternates:normal;vertical-align:baseline">Allow no one to steal vu=
lnerable coins.</span></p></li></ol></ol><li dir=3D"ltr" style=3D"list-styl=
e-type:disc;font-size:11pt;font-family:&quot;Courier New&quot;,monospace;co=
lor:rgb(0,0,0);background-color:transparent;font-weight:700;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;background-color:transparent;font-vari=
ant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:n=
ormal;vertical-align:baseline">Minimizes attack surface</span></p></li><ol =
style=3D"margin-top:0px;margin-bottom:0px"><li dir=3D"ltr" style=3D"list-st=
yle-type:lower-alpha;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;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-num=
eric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;v=
ertical-align:baseline">By disallowing new spends to quantum vulnerable scr=
ipt types, we minimize the attack surface with each new UTXO.=C2=A0=C2=A0</=
span></p></li><li dir=3D"ltr" style=3D"list-style-type:lower-alpha;font-siz=
e:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);backg=
round-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-color:transparent;font-variant-numeric:normal;font-variant-east=
-asian:normal;font-variant-alternates:normal;vertical-align:baseline">Upgra=
des to Bitcoin have historically taken many years; this will hasten and spe=
ed up the adoption of new quantum resistant script types.=C2=A0</span></p><=
/li><li dir=3D"ltr" style=3D"list-style-type:lower-alpha;font-size:11pt;fon=
t-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-colo=
r:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;fo=
nt-variant-alternates:normal;vertical-align:baseline;white-space:pre"><p di=
r=3D"ltr" style=3D"line-height:1.38;text-align:justify;margin-top:0pt;margi=
n-bottom:0pt" role=3D"presentation"><span style=3D"font-size:11pt;backgroun=
d-color:transparent;font-variant-numeric:normal;font-variant-east-asian:nor=
mal;font-variant-alternates:normal;vertical-align:baseline">With a clear de=
adline, industry stakeholders will more readily upgrade existing infrastruc=
ture to ensure continuity of services.=C2=A0=C2=A0</span></p></li></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:transparent;f=
ont-weight:700;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">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&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:12pt" role=3D"presentation"><span style=3D"font-size:11pt=
;background-color:transparent;font-variant-numeric:normal;font-variant-east=
-asian:normal;font-variant-alternates:normal;vertical-align:baseline">If th=
ere is sufficient demand and research proves possible, submitting a ZK proo=
f of 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 spe=
nt 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;border-collapse:collapse"><colgroup><col =
width=3D"143"><col width=3D"539"></colgroup><tbody><tr style=3D"height:27.4=
463pt"><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;margin-top:0pt;margin-bottom:0pt"><span style=3D"font-=
size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);ba=
ckground-color:transparent;font-weight:700;font-variant-numeric:normal;font=
-variant-east-asian:normal;font-variant-alternates:normal;vertical-align:ba=
seline">Stakeholder</span></p></td><td style=3D"border-width:1pt;border-sty=
le: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;margin-top:0pt;margin-bottom=
:0pt"><span style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,mon=
ospace;color:rgb(0,0,0);background-color:transparent;font-weight:700;font-v=
ariant-numeric:normal;font-variant-east-asian:normal;font-variant-alternate=
s:normal;vertical-align:baseline">Incentive to Upgrade</span></p></td></tr>=
<tr style=3D"height:53.5388pt"><td style=3D"border-width:1pt;border-style:s=
olid;border-color:rgb(0,0,0);vertical-align:middle;padding:5pt;overflow:hid=
den"><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;,mono=
space;color:rgb(0,0,0);background-color:transparent;font-weight:700;font-va=
riant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates=
:normal;vertical-align:baseline">Miners</span></p></td><td style=3D"border-=
width:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-align:top;pad=
ding:5pt;overflow:hidden"><p dir=3D"ltr" style=3D"line-height:1.38;margin-t=
op:0pt;margin-bottom:0pt"><span style=3D"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">=E2=80=A2 Larger size PQ signatures a=
long with incentive for users to migrate will create more demand for block =
space and thus higher fees collected by miners.</span></p><p dir=3D"ltr" st=
yle=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"fo=
nt-size:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0)=
;background-color:transparent;font-variant-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-family:&quot;Courier New&quot;,monospace=
;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;=
font-variant-east-asian:normal;font-variant-alternates:normal;vertical-alig=
n:baseline">=E2=80=A2 A quantum attack on Bitcoin will significantly devalu=
e both their hardware and Bitcoin as a whole.=C2=A0</span></p></td></tr><tr=
 style=3D"height:52pt"><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:11pt;font-family:&quot;Courier New&quot;,monospace;co=
lor:rgb(0,0,0);background-color:transparent;font-weight:700;font-variant-nu=
meric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;=
vertical-align:baseline">Institutional Holders</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;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-variant-numeric:normal;font-variant-east-asian:normal;font-varian=
t-alternates:normal;vertical-align:baseline">=E2=80=A2 Fiduciary duty: fail=
ing to act to prevent a quantum attack on Bitcoin would violate the fiducia=
ry duty to shareholders.=C2=A0=C2=A0</span></p><p dir=3D"ltr" style=3D"line=
-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"font-size:11p=
t;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background=
-color:transparent;font-variant-numeric:normal;font-variant-east-asian:norm=
al;font-variant-alternates:normal;vertical-align:baseline">=E2=80=A2 Demons=
trating Bitcoin=E2=80=99s ability to effectively mitigate emerging threats =
will prove Bitcoin to be an investment grade asset.</span></p></td></tr><tr=
 style=3D"height:52pt"><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:11pt;font-family:&quot;Courier New&quot;,monospace;co=
lor:rgb(0,0,0);background-color:transparent;font-weight:700;font-variant-nu=
meric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;=
vertical-align:baseline">Exchanges &amp; Custodians</span></p></td><td styl=
e=3D"border-width:1pt;border-style:solid;border-color:rgb(0,0,0);vertical-a=
lign: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-fa=
mily:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:tr=
ansparent;font-variant-numeric:normal;font-variant-east-asian:normal;font-v=
ariant-alternates:normal;vertical-align:baseline">=E2=80=A2 Concentrated ri=
sk: a quantum hack could bankrupt them overnight.</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-variant-numeric:normal;font-variant-ea=
st-asian:normal;font-variant-alternates:normal;vertical-align:baseline">=E2=
=80=A2 Early migration is cheap relative to potential losses, potential law=
suits over improper custody and reputational damage.</span></p></td></tr><t=
r style=3D"height:52pt"><td style=3D"border-width:1pt;border-style:solid;bo=
rder-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"><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">Everyday Users</span></p></td><td style=3D"border=
-width:1pt;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;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;f=
ont-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alte=
rnates:normal;vertical-align:baseline">=E2=80=A2 Self-sovereign peace of mi=
nd.</span></p><p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margi=
n-bottom:0pt"><span style=3D"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">=E2=80=A2 Sunset date creates a clear deadline an=
d incentive to improve their security rather than an open-ended =E2=80=9Cso=
me day=E2=80=9D that invites procrastination.</span></p></td></tr><tr style=
=3D"height:43.7925pt"><td style=3D"border-width:1pt;border-style:solid;bord=
er-color:rgb(0,0,0);vertical-align:middle;padding:5pt;overflow:hidden"><p d=
ir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><spa=
n style=3D"font-size:11pt;font-family:&quot;Courier New&quot;,monospace;col=
or:rgb(0,0,0);background-color:transparent;font-weight:700;font-variant-num=
eric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;v=
ertical-align:baseline">Attackers</span></p></td><td style=3D"border-width:=
1pt;border-style:solid;border-color:rgb(0,0,0);vertical-align:top;padding:5=
pt;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-var=
iant-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 spent 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;f=
ont-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-co=
lor:transparent;font-weight:700;font-variant-numeric:normal;font-variant-ea=
st-asian:normal;font-variant-alternates:normal;vertical-align:baseline">Key=
 Insight:</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:norm=
al;vertical-align:baseline"> As mentioned earlier, the proposal turns quant=
um security into a </span><span style=3D"font-size:11pt;font-family:&quot;C=
ourier New&quot;,monospace;color:rgb(0,0,0);background-color:transparent;fo=
nt-style:italic;font-variant-numeric:normal;font-variant-east-asian:normal;=
font-variant-alternates:normal;vertical-align:baseline">private incentive t=
o 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:norm=
al;vertical-align:baseline">.=C2=A0=C2=A0</span></p><p dir=3D"ltr" style=3D=
"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style=3D"font-siz=
e:11pt;font-family:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);backg=
round-color:transparent;font-variant-numeric:normal;font-variant-east-asian=
:normal;font-variant-alternates:normal;vertical-align:baseline">This is not=
 an offensive attack, rather, it is defensive: our thesis is that the Bitco=
in ecosystem wishes to defend itself and its interests against those who wo=
uld 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;m=
argin-top:0pt;margin-bottom:0pt"><span style=3D"background-color:transparen=
t;color:rgb(0,0,0);font-family:&quot;Courier New&quot;,monospace;font-size:=
11pt;text-align:center"><br></span></p><blockquote style=3D"margin:0px 0px =
0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex" class=3D=
"gmail_quote"><span style=3D"background-color:transparent;color:rgb(0,0,0);=
font-family:&quot;Courier New&quot;,monospace;font-size:11pt;text-align:cen=
ter">&quot;Lost coins only make everyone else&#39;s coins worth slightly mo=
re. Think of it as a donation to everyone.&quot; - Satoshi Nakamoto</span><=
/blockquote><br><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;Courier New=
&quot;,monospace;color:rgb(0,0,0);background-color:transparent;font-variant=
-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:norm=
al;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 styl=
e=3D"background-color:transparent;color:rgb(0,0,0);font-family:&quot;Courie=
r New&quot;,monospace;font-size:11pt;text-align:center"><br></span></p><blo=
ckquote 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"background-col=
or:transparent;color:rgb(0,0,0);font-family:&quot;Courier New&quot;,monospa=
ce;font-size:11pt;text-align:center">&quot;Quantum recovered coins only mak=
e everyone else&#39;s coins worth less. Think of it as a theft from everyon=
e.&quot;</span></blockquote><br><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-variant-numeric:normal;font-variant-east-asian:normal;font-variant=
-alternates:normal;vertical-align:baseline">The timelines that we are propo=
sing are meant to find the best balance between giving ample ability for ac=
count owners to migrate while maintaining the integrity of the overall ecos=
ystem to avoid catastrophic attacks.=C2=A0=C2=A0</span></p><br><h2 dir=3D"l=
tr" style=3D"line-height:1.38;margin-top:18pt;margin-bottom:4pt"><span styl=
e=3D"font-size:17pt;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:baseline=
">Backward Compatibility</span></h2><p dir=3D"ltr" style=3D"line-height:1.3=
8;margin-top:0pt;margin-bottom:0pt"><span style=3D"font-size:11pt;font-fami=
ly:&quot;Courier New&quot;,monospace;color:rgb(0,0,0);background-color:tran=
sparent;font-variant-numeric:normal;font-variant-east-asian:normal;font-var=
iant-alternates:normal;vertical-align:baseline">As a series of soft forks, =
older nodes will continue to operate without modification. Non-upgraded nod=
es, however, will consider all post-quantum witness programs as anyone-can-=
spend scripts. They are strongly encouraged to upgrade in order to fully va=
lidate 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-f=
amily:&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">Non-upgraded wallets can=
 receive and send bitcoin from non-upgraded and upgraded wallets until Phas=
e A. After Phase A, they can no longer receive from any other wallets and c=
an only send to upgraded wallets.=C2=A0 After Phase B, both senders and rec=
eivers will require upgraded wallets.=C2=A0Phase C would likely require a l=
oosening of consensus rules (a hard fork) to allow vulnerable funds recover=
y via ZK proofs.</span></p></span></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/CADL_X_fpv-aXBxX%2BeJ_EVTirkAJGyPRUNqOCYdz5um8zu6ma5Q%40mail.gma=
il.com?utm_medium=3Demail&utm_source=3Dfooter">https://groups.google.com/d/=
msgid/bitcoindev/CADL_X_fpv-aXBxX%2BeJ_EVTirkAJGyPRUNqOCYdz5um8zu6ma5Q%40ma=
il.gmail.com</a>.<br />

--000000000000123e1d0639c239f9--