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[2a00:1450:4864:20::22a]) by gmr-mx.google.com with ESMTPS id a640c23a62f3a-b93376f6cd1si12261966b.1.2026.02.25.08.46.16 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 25 Feb 2026 08:46:16 -0800 (PST) Received-SPF: pass (google.com: domain of jameson.lopp@gmail.com designates 2a00:1450:4864:20::22a as permitted sender) client-ip=2a00:1450:4864:20::22a; Received: by mail-lj1-x22a.google.com with SMTP id 38308e7fff4ca-38706b10b3bso69424061fa.1 for ; Wed, 25 Feb 2026 08:46:16 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1772037975; cv=none; d=google.com; s=arc-20240605; b=LeSdjjHLgX5ttCGS4p2o2Lnr8WMx1VEFVy0KtHBqQgefhHSOzDuLRUOddSunhlDWRK 524vt+bGTzsTyTCNAgQ5P/y8uI2ux5CdKdYf3IX0SQcODdhlhjLCb7RIDSZb0LSyGYv7 dxvuY5TTPKb0ncSgFZRK1J57gFrlTstxhZZKrZJQ8uheyJrDlNNEhAAs+XQ9jJq0ZrDq uduXs92zTf23BFQzPDRRLSZgPkAyVpW+x966/FFordwIj2uFWmS0Y1VgZ13smhnWmiq6 u/V45cHgPU+uHJv8LEmO+duCz397g7SuG62IkMNg7V/+I57FRgTS16+VASK2jXljALoF P5tA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20240605; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=dfnvE+JHG03d5Ds+OhA7z1ILaaJI/fq8VOWIwBqE394=; fh=tf0wv6edLGSbWkCCzJcCE6rk/JV+fvIucdiuI4sSMuo=; b=P3gB6ao3YzvdN5pXPHbcIT1aQr+WRkEV+JqYtzoIfvJLRzYbe/djcJvY6i43j7NBSu 0RBvpp1KjTcNJupt+Rc0F0kT9GiL9zB2mUbwNaEajyeiHAMNUwlWfJd+d5hE9ZCipZtA lvSdKhLfgczjRM/u6/95sU5zOVCXlNRyJjH1WL2uxR+7Rc++N5K11YYD1h6qi1BvzbXu QAzrrOjT/hdN1Nbpi6kTyeOs1eWIMEvEDA5IPvf1fVZE/hYuM7bqqzL3NvhMZCUXdEE6 pp8tAkknX6mApjOytQA6XapDPnhBI8OaEbs64OBhrJemxc34YCP12xSH/5TNRRe4uvEB O4Sw==; dara=google.com ARC-Authentication-Results: i=1; mx.google.com; arc=none X-Gm-Gg: ATEYQzwO1jI2EOnkjxYPLhRun7wH8xLUY4n0HVeqpVCoVdjuhTxjzk1O4NLHzpxHhH3 msTNHhWOhZL/KJvFNRWKxS3nZt0LJMXFDwmEozoij+B+wKJRfQfMgMllCciKGNOvQT+zBGTPQXy hd2332cyPAmCLD+M8EYfQNIUtZnSlJW+q43gEqrevM+3Cm3of5ljVnwPkq2e9U0KBqYm5JFo5zA h9ozk5cNzasevuzzbik0MIQ9pSOFXjx2U8WMYqUUSztcm+sX72nkCTvDZzpTc7oHWWl6BMx/Zly 6kTbteG4X3R67s/s2p2joqv4jsXE70YznF18rZfr0UOL4CMh680Dx7uCqYegZDyq2VAgDMBYxJS fuquudF6HV4a9NqE6XncTQApcyCP0OvkalB9q X-Received: by 2002:a05:6512:3f24:b0:59d:e589:c973 with SMTP id 2adb3069b0e04-5a1060a2717mr304896e87.48.1772037974842; Wed, 25 Feb 2026 08:46:14 -0800 (PST) MIME-Version: 1.0 References: <9336f5a4-5c28-4c1b-af29-a8462b7a9377n@googlegroups.com> <57bd09bc-1c1b-4605-82f9-65b6b61cf8a2@app.fastmail.com> <4b02a925-663f-423f-8905-0fc1b528581fn@googlegroups.com> In-Reply-To: From: Jameson Lopp Date: Wed, 25 Feb 2026 11:46:02 -0500 X-Gm-Features: AaiRm50b6cMRCQjO1QqkMFSx_ONYzgK-9VXMmUEYNjXcsoXmD-tJgVHQOI48xr8 Message-ID: Subject: Re: [bitcoindev] Hourglass V2 Update To: Bob Burnett Cc: Bitcoin Development Mailing List Content-Type: multipart/alternative; boundary="00000000000004e3ef064ba8beda" 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=D7WsOHTJ; arc=pass (i=1); spf=pass (google.com: domain of jameson.lopp@gmail.com designates 2a00:1450:4864:20::22a 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: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -0.5 (/) --00000000000004e3ef064ba8beda Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Ultimately, I believe that the network should nudge people toward using best practices, whatever that may be. Are there any strong reasons why the network should treat P2PK as a first class citizen, so to speak? It has both security flaws and is disincentivized for use from a transaction weight and thus fees perspective= . A proposal such as hourglass provides an additional nudge in the direction of "this is deprecated, don't use it." On Wed, Feb 25, 2026 at 10:02=E2=80=AFAM Bob Burnett wrote: > > 1 BTC might actually make sense and not be so arbitrary=E2=80=94as it = will be > an easy number for people to track and understand what coins they can mov= e > or are moving at any given time. > > I very much agree that keeping things easy for people should be a high > priority. As opposed to a % of the block reward or subsidy, one suggesti= on > is to use something like the halving we use for the subsidy. Start with = a > maximum of 1 or 2 BTC per block and reduce the amount by half on the same > 210,000 block schedule as the subsidy halving. People seem to get that > concept well and I think it would work here too. Alternatively, we could > use the same schedule but do doubling. Start with a very small number li= ke > 1M Sats and then build to a bigger number in the future. This takes away > the incentive for an early attacker and means the bigger prizes for the > quantum attackers would come in a period when there is massive competitio= n > from the quantum world and much more economic uncertainty for an individu= al > quantum attacker. > > I must admit that this does create a bit of quandary regarding property > rights and that does bother me, but if the decision is to do something to > slow down the attackers this, does seem like a reasonable approach. Also= , > by spreading this out over several decades and restricting block space > access, it means that there will likely be numerous quantum attackers, an= d > they will be competing with each other not only for the private keys but > also for the prized spot in each block (good news for fees). > > > *From: *bitcoindev@googlegroups.com on > behalf of Isabel Foxen Duke > *Date: *Monday, February 23, 2026 at 1:51=E2=80=AFPM > *To: *Bitcoin Development Mailing List > *Subject: *Re: [bitcoindev] Hourglass V2 Update > > > [1 BTC] can be replaced with something else. For example, if things ar= e > based on the coinbase reward, then these rules can be wired into consensu= s. > Which means, that if the current block reward is 3.125 BTC plus fees, the= n > P2PKs can be limited to be X% of the coinbase, and not more than that. > > I don't mind this idea =E2=80=94 however, I worry it could add complexity= from a > user experience perspective. 1 BTC might actually make sense and not be s= o > arbitrary=E2=80=94as it will be an easy number for people to track and un= derstand > what coins they can move or are moving at any given time. Hyper-simplicit= y > has UX and comms benefits. > > -Isabel > > On Tuesday, February 17, 2026 at 9:11:45=E2=80=AFAM UTC-4 Garlo Nicon wro= te: > > > My primary complaint is that 1 BTC per block is somewhat arbitrary. > > > Hourglass V2 further restricts the output amount to a maximum of 1 > bitcoin per block, or roughly 144 bitcoin per day. This is far less than > the 450 coins per day introduced by the current block reward subsidy, and > should effectively mitigate the market impacts of quantum attacks on P2PK > coins. > > It can be replaced with something else. For example, if things are based > on the coinbase reward, then these rules can be wired into consensus. Whi= ch > means, that if the current block reward is 3.125 BTC plus fees, then P2PK= s > can be limited to be X% of the coinbase, and not more than that. It would > still be arbitrary, but it would be more aligned with the explanation fro= m > the BIP, that it is all about how many coins are introduced into > circulation, or assigned to miners. > > Or, if it would be based only on the basic block reward, without fees, > then when all coins will be mined, P2PKs will automatically expire, becau= se > there won't be any amount, which is less than zero satoshis. Because thin= gs > can be based on fees, but then, a large miner with many coins, could game > the system, and turn some of his own coins into fees, only to unlock more > P2PK coins. > > pon., 16 lut 2026 o 23:11 Jameson Lopp napisa=C5=82= (a): > > Bitcoin is ultimately a system of rules that are enforced by those who us= e > the system and hold the keys to spend UTXOs. As such, if a sufficiently > large cohort of economic power within the system is interested in > protecting itself against massive liquidation events from malicious actor= s > who arguably are not the rightful owners of UTXOs, the incentives are in > place for them to do something about it. > > I like Hourglass V2 a lot more than V1. My primary complaint is that 1 BT= C > per block is somewhat arbitrary. It would be interesting to point to the > on-chain statistics of what P2PK UTXO spend volume we have seen in recent > years. > > Additionally, in the context of my own migration BIP, Hourglass V2 could > be complementary to the concept of offering a ZK quantum safe spending > option for folks who fail to migrate UTXOs to quantum safe scripts before= a > set deadline, given that these old P2PK outputs do not belong to HD walle= ts > and thus the owners would be incapable of constructing a ZK proof of HD > wallet ownership. > > On Fri, Feb 13, 2026 at 5:12=E2=80=AFPM Light wrote= : > > Bitcoin should not have an in-protocol plunge protection mechanism, and > certainly not one that artificially restricts people's ability to spend > their coins. I encourage you to withdraw this proposal, for the sake of > bitcoin's integrity and utility as a p2p electronic cash system. > > On Tue, Feb 10, 2026, at 3:47 PM, Mike Casey wrote: > > In response to feedback, the Hourglass proposal to mitigate against > > potential mass liquidation of P2PK funds has been enhanced to further > > limit spend amounts from such outputs to only 1 bitcoin per block. > > > https://github.com/cryptoquick/bips/blob/hourglass-v2/bip-hourglass-v2.me= diawiki > > > > Prior discussion of the original Hourglass proposal: > > https://groups.google.com/g/bitcoindev/c/zmg3U117aNc/m/lDCMs9j7EAAJ > > > > Thoughts & feedback welcome! > > > > -- > > 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 email to bitcoindev+...@googlegroups.com. > > To view this discussion visit > > > https://groups.google.com/d/msgid/bitcoindev/9336f5a4-5c28-4c1b-af29-a846= 2b7a9377n%40googlegroups.com > > < > https://groups.google.com/d/msgid/bitcoindev/9336f5a4-5c28-4c1b-af29-a846= 2b7a9377n%40googlegroups.com?utm_medium=3Demail&utm_source=3Dfooter > >. > > -- > 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 > email to bitcoindev+...@googlegroups.com. > To view this discussion visit > https://groups.google.com/d/msgid/bitcoindev/57bd09bc-1c1b-4605-82f9-65b6= b61cf8a2%40app.fastmail.com > . > > -- > 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 > email to bitcoindev+...@googlegroups.com. > > To view this discussion visit > https://groups.google.com/d/msgid/bitcoindev/CADL_X_eb8byZs3VKORoUzaPoBvg= uSbxJ%3DKyKifsQFWFqyqHeRA%40mail.gmail.com > > . > > -- > 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 > email to bitcoindev+unsubscribe@googlegroups.com. > To view this discussion visit > https://groups.google.com/d/msgid/bitcoindev/4b02a925-663f-423f-8905-0fc1= b528581fn%40googlegroups.com > > . > > -- > 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 > email to bitcoindev+unsubscribe@googlegroups.com. > To view this discussion visit > https://groups.google.com/d/msgid/bitcoindev/BY5PR03MB51717E25CEB9444CF24= 63E0C9675A%40BY5PR03MB5171.namprd03.prod.outlook.com > > . > --=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_cMby9KY8o7RSUV8SW7aqpbDWhiaOm%2B7nS-GGHjFeMk0w%40mail.gmail.com. --00000000000004e3ef064ba8beda Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Ultimately, I believe that the network should nudge people= toward using best practices, whatever that may be.

Are there any s= trong reasons why the network should treat P2PK as a first class citizen, s= o to speak? It has both security flaws and is disincentivized for use from = a transaction weight and thus fees perspective.

A = proposal such as hourglass provides an additional nudge in the direction of= "this is deprecated, don't use it."

On Wed, Feb 25, 2026 at 10:02=E2=80=AFAM Bob Burnett <bob.burnett@barefootmining.com> w= rote:
> =C2=A01 BTC might actually make sense and not be so arbitrary=E2=80=94= as it will be an easy number for people to track and understand what coins = they can move or are moving at any given time.
<= b>
I very much a= gree that keeping things easy for people should be a high priority.=C2=A0 A= s opposed to a % of the block reward or subsidy, one suggestion is to use s= omething like the halving we use for the subsidy.=C2=A0 Start with a maximum of 1 or 2 BTC per block and re= duce the amount by half on the same 210,000 block schedule as the subsidy h= alving.=C2=A0 People seem to get that concept well and I think it would wor= k here too.=C2=A0 Alternatively, we could use the same schedule but do doubling.=C2=A0 Start with a very small number like 1= M Sats and then build to a bigger number in the future.=C2=A0 This takes aw= ay the incentive for an early attacker and means the bigger prizes for the = quantum attackers would come in a period when there is massive competition from the quantum world and much more economic= uncertainty for an individual quantum attacker.

I must admit = that this does create a bit of quandary regarding property rights and that = does bother me, but if the decision is to do something to slow down the att= ackers this, does seem like a reasonable approach.=C2=A0 Also, by spreading this out over several deca= des and restricting block space access, it means that there will likely be = numerous quantum attackers, and they will be competing with each other not = only for the private keys but also for the prized spot in each block (good news for fees). =C2=A0
<= br>
<= br>
<= b>From: bitcoi= ndev@googlegroups.com <bitcoindev@googlegroups.com> on behalf of Isabel= Foxen Duke <= isabel.duke@gmail.com>
Date: Monday, February 23, 2026 at 1:51=E2=80=AFPM
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com> Subject: Re: [bitcoindev] Hourglass V2 Update

>=C2=A0 [1 BTC] can be replaced with something else. For example, i= f things are based on the coinbase reward, then these rules can be wired in= to consensus. Which means, that if the current block reward is 3.125 BTC plus fees, then P2PKs can be limited to be X% of the coinbase= , and not more than that.

I don't mind this idea =E2=80=94 however, I worry it could add complexi= ty from a user experience perspective. 1 BTC might actually make sense and = not be so arbitrary=E2=80=94as it will be an easy number for people to trac= k and understand what coins they can move or are moving at any=C2=A0given time. Hyper-simplicity has UX and comms benefits.=C2=A0= =C2=A0 =C2=A0 =C2=A0

-Isabel

On Tuesday, February 17, = 2026 at 9:11:45=E2=80=AFAM UTC-4 Garlo Nicon wrote:
> My primary complain= t is=C2=A0that 1 BTC per block is somewhat arbitrary.

> Hourglass V2 furthe= r restricts the output amount to a maximum of 1 bitcoin per block, or rough= ly 144 bitcoin per day. This is far less than the 450 coins per day introdu= ced by the current block reward subsidy, and should effectively mitigate the market impacts of quantum attacks on P= 2PK coins.

It can be replaced with something else. For example, if things are based on= the coinbase reward, then these rules can be wired into consensus. Which m= eans, that if the current block reward is 3.125 BTC plus fees, then P2PKs c= an be limited to be X% of the coinbase, and not more than that. It would still be arbitrary, but it would be more = aligned with the explanation from the BIP, that it is all about how many co= ins are introduced into circulation, or assigned to miners.

Or, if it would be based only on the basic block reward, without fees, then= when all coins will be mined, P2PKs will automatically expire, because the= re won't be any amount, which is less than zero satoshis. Because thing= s can be based on fees, but then, a large miner=C2=A0with many coins, could game the system, and turn some of = his own coins into fees, only to unlock more P2PK coins.

pon., 16 lut 2026 o 23:11= =C2=A0Jameson Lopp <jameso...@gmail.com> napisa=C5=82(a):
Bitcoin is ultimately a = system of rules that are enforced by those who use the system and hold the = keys to spend UTXOs. As such, if a sufficiently large cohort of economic po= wer within the system is interested in protecting itself against massive liquidation events from malicious act= ors who arguably are not the rightful owners of UTXOs, the incentives are i= n place for them to do something about it.

I like Hourglass V2 a lo= t more than V1. My primary complaint is that 1 BTC per block is somewhat ar= bitrary. It would be interesting to point to the on-chain statistics of wha= t P2PK UTXO spend volume we have seen in recent years.

Additionally, in the context of my own migration BIP, Hourglass V2 could be= complementary to the concept of offering a ZK quantum safe spending option= for folks who fail to migrate UTXOs to quantum safe scripts before a set d= eadline, given that these old P2PK outputs do not belong to HD wallets and thus the owners would be incapable= of constructing a ZK proof of HD wallet ownership.

On Fri, Feb 13, 2026 at 5= :12=E2=80=AFPM Light <bitco...@lightco.in> wrote:
Bitcoin should not have an in-protocol plunge pr= otection mechanism, and certainly not one that artificially restricts peopl= e's ability to spend their coins. I encourage you to withdraw this prop= osal, for the sake of bitcoin's integrity and utility as a p2p electronic cash system.

On Tue, Feb 10, 2026, at 3:47 PM, Mike Casey wrote:
> In response to feedback, the Hourglass proposal to mitigate against > potential mass liquidation of P2PK funds has been enhanced to further<= br> > limit spend amounts from such outputs to only 1 bitcoin per block.
> https://github.com/cryptoquick/bips/blob/hourglass-v2/bip-hourglass-v2.medi= awiki
>
> Prior discussion of the original Hourglass proposal:
> https://groups.google.com/g/bitcoindev/c/zmg3U117aNc/m/lDCMs9j7EAAJ
>
> Thoughts & feedback welcome!
>
> --
> 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 email to bitcoindev+...@googlegroups.com.
> To view this discussion visit
> https://groups.google.com/d/msgid/bitcoindev/9336f5a4-5c28-4c1b-af29-a8462b= 7a9377n%40googlegroups.com
> <https://group= s.google.com/d/msgid/bitcoindev/9336f5a4-5c28-4c1b-af29-a8462b7a9377n%40goo= glegroups.com?utm_medium=3Demail&utm_source=3Dfooter>.

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