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Wed, 18 Feb 2026 07:20:10 -0800 (PST) X-Received: by 2002:a05:6808:14cf:b0:462:fc10:d8a9 with SMTP id 5614622812f47-46410afae4bmr1067021b6e.9.1771428010746; Wed, 18 Feb 2026 07:20:10 -0800 (PST) Received: by 2002:a05:690c:450f:b0:797:d142:b0fa with SMTP id 00721157ae682-797d142c175ms7b3; Wed, 18 Feb 2026 06:33:39 -0800 (PST) X-Received: by 2002:a05:690c:1e:b0:796:6ccf:cf11 with SMTP id 00721157ae682-797f7105b79mr14264807b3.22.1771425218673; Wed, 18 Feb 2026 06:33:38 -0800 (PST) Date: Wed, 18 Feb 2026 06:33:38 -0800 (PST) From: Mike Casey To: Bitcoin Development Mailing List Message-Id: In-Reply-To: References: <9336f5a4-5c28-4c1b-af29-a8462b7a9377n@googlegroups.com> <57bd09bc-1c1b-4605-82f9-65b6b61cf8a2@app.fastmail.com> Subject: Re: [bitcoindev] Hourglass V2 Update MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_164454_2056106719.1771425218305" X-Original-Sender: mcasey0827@gmail.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 (/) ------=_Part_164454_2056106719.1771425218305 Content-Type: multipart/alternative; boundary="----=_Part_164455_2084075261.1771425218305" ------=_Part_164455_2084075261.1771425218305 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Admittedly, the actual value is arbitrary, but it's very easy to relay=20 conceptually which helps communicate the concept and dissuade this=20 particular branch of quantum FUD. Fundamentally, it's a trade off between= =20 how quickly the entire set can be liquidated (if keys are cracked in=20 advance) and how long and individual original keyholder has to wait to be= =20 able to exercise dominion over their P2PK coins. In addition to memetics,= =20 the 1 BTC amount should provide a very lengthy liquidation period assuming= =20 most P2PK keys are lost and cannot be moved prior to implementation. On Monday, February 16, 2026 at 5:11:09=E2=80=AFPM UTC-5 Jameson Lopp wrote= : > Bitcoin is ultimately a system of rules that are enforced by those who us= e=20 > the system and hold the keys to spend UTXOs. As such, if a sufficiently= =20 > large cohort of economic power within the system is interested in=20 > protecting itself against massive liquidation events from malicious actor= s=20 > who arguably are not the rightful owners of UTXOs, the incentives are in= =20 > 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=20 > per block is somewhat arbitrary. It would be interesting to point to the= =20 > on-chain statistics of what P2PK UTXO spend volume we have seen in recent= =20 > years. > > Additionally, in the context of my own migration BIP, Hourglass V2 could= =20 > be complementary to the concept of offering a ZK quantum safe spending=20 > option for folks who fail to migrate UTXOs to quantum safe scripts before= a=20 > set deadline, given that these old P2PK outputs do not belong to HD walle= ts=20 > and thus the owners would be incapable of constructing a ZK proof of HD= =20 > 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= =20 >> certainly not one that artificially restricts people's ability to spend= =20 >> their coins. I encourage you to withdraw this proposal, for the sake of= =20 >> 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=20 >> > potential mass liquidation of P2PK funds has been enhanced to further= =20 >> > limit spend amounts from such outputs to only 1 bitcoin per block. >> >=20 >> https://github.com/cryptoquick/bips/blob/hourglass-v2/bip-hourglass-v2.m= ediawiki >> > >> > Prior discussion of the original Hourglass proposal: >> > https://groups.google.com/g/bitcoindev/c/zmg3U117aNc/m/lDCMs9j7EAAJ >> > >> > Thoughts & feedback welcome! >> > >> > --=20 >> > You received this message because you are subscribed to the Google=20 >> > Groups "Bitcoin Development Mailing List" group. >> > To unsubscribe from this group and stop receiving emails from it, send= =20 >> > an email to bitcoindev+...@googlegroups.com. >> > To view this discussion visit=20 >> >=20 >> https://groups.google.com/d/msgid/bitcoindev/9336f5a4-5c28-4c1b-af29-a84= 62b7a9377n%40googlegroups.com=20 >> > < >> https://groups.google.com/d/msgid/bitcoindev/9336f5a4-5c28-4c1b-af29-a84= 62b7a9377n%40googlegroups.com?utm_medium=3Demail&utm_source=3Dfooter >> >. >> >> --=20 >> You received this message because you are subscribed to the Google Group= s=20 >> "Bitcoin Development Mailing List" group. >> To unsubscribe from this group and stop receiving emails from it, send a= n=20 >> email to bitcoindev+...@googlegroups.com. >> > To view this discussion visit=20 >> https://groups.google.com/d/msgid/bitcoindev/57bd09bc-1c1b-4605-82f9-65b= 6b61cf8a2%40app.fastmail.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/= d8a38970-952d-4c8c-9ba5-2dfd79e70147n%40googlegroups.com. ------=_Part_164455_2084075261.1771425218305 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Admittedly, the actual value is arbitrary, but it's very easy to relay conc= eptually which helps communicate the concept and dissuade this particular b= ranch of quantum FUD.=C2=A0 Fundamentally, it's a trade off between how qui= ckly the entire set can be liquidated (if keys are cracked in advance) and = how long and individual original keyholder has to wait to be able to exerci= se dominion over their P2PK coins.=C2=A0 In addition to memetics, the 1 BTC= amount should provide a very lengthy liquidation period assuming most P2PK= keys are lost and cannot be moved prior to implementation.
On Monday, February= 16, 2026 at 5:11:09=E2=80=AFPM UTC-5 Jameson Lopp wrote:
Bitcoin is ul= timately a system of rules that are enforced by those who use the system an= d 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 actors who arguably are not the = rightful owners of UTXOs, the incentives are in place for them to do someth= ing about it.

I like Hourglass V2 a lot more than V1. My= primary complaint is that 1 BTC 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 o= f 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 P= 2PK outputs do not belong to HD wallets and thus the owners would be incapa= ble 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:
<= /div>
Bitcoin should not have an in-protocol plunge protection mecha= nism, and certainly not one that artificially restricts people's abilit= y 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.m= ediawiki
>
> Prior discussion of the original Hourglass proposal:
> https://groups.google.c= om/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-a8462b7a9377n%40googlegroups.com
> <https://groups.= google.com/d/msgid/bitcoindev/9336f5a4-5c28-4c1b-af29-a8462b7a9377n%40googl= egroups.com?utm_medium=3Demail&utm_source=3Dfooter>.

--
You received this message because you are subscribed to the Google Groups &= quot;Bitcoin Development Mailing List" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to bitcoindev+...@googlegro= ups.com.
To view this discussion visit https= ://groups.google.com/d/msgid/bitcoindev/57bd09bc-1c1b-4605-82f9-65b6b61cf8a= 2%40app.fastmail.com.

--
You received this message because you are subscribed to the Google Groups &= quot;Bitcoin Development Mailing List" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to bitcoind= ev+unsubscribe@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/bitcoind= ev/d8a38970-952d-4c8c-9ba5-2dfd79e70147n%40googlegroups.com.
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