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From: gmaxwell <gmaxwell@gmail.com>
Date: Sat, 14 Jun 2025 16:06:07 +0000
Message-ID: <CAAS2fgSo=pdRhj=MkRDObXm5GtKpP3R5T4yck_pwBpn3_72f5Q@mail.gmail.com>
Subject: Re: [bitcoindev] CTV + CSFS: a letter
To: Jameson Lopp <jameson.lopp@gmail.com>
Cc: Antoine Poinsot <darosior@protonmail.com>, Matt Corallo <lf-lists@mattcorallo.com>, 
	Andrew Poelstra <apoelstra@wpsoftware.net>, 
	Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
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I'm struggling to figure out what kind of useful 'vault' could be
constructed from CTV that isn't equivalent to "presign a transaction that
sweeps your funds to an emergency address".  Can someone clue me in?

It might be helpful to point to examples of where similar techniques are
used in other blockchains that already facilitate their construction.  This
isn't bitcoin-twitter,  it's permissible to observe some other system being
used in useful ways...


On Sat, Jun 14, 2025 at 2:08=E2=80=AFPM Jameson Lopp <jameson.lopp@gmail.co=
m> wrote:

> Casa (and many other companies focused on custody products) would love to
> see vaulting functionality. I don't think any of us are too hung up on th=
e
> details of the particular implementation - we would rather have a "good"
> tool than not have any tool because consensus has not been achieved for a
> "perfect" solution.
>
> What is the problem that makes vaults desirable? It's frankly because
> there's no such thing as perfect security. Even if one designs an
> architecture that is nearly perfectly secure against external threats, th=
e
> issue of internal threats (such as oneself, via social engineering) will
> remain. The ability to require high value funds to sit in a "quarantine /
> cooldown" address for some period of time before they can be sent to an
> arbitrary address enables additional security measures a la watchtowers t=
o
> be designed. Being your own bank is still an incredibly scary proposition
> because it's quite difficult to design custody solutions that tolerate
> failures without leading to catastrophic loss. The more tools that custod=
y
> application engineers have available to them, the more guardrails we can
> build into wallet software, and thus hopefully the more comfortable we ca=
n
> make the general public with the idea of taking on the responsibility of
> self custody.
>
> To be clear, I'm not aware of CSFS improving the vaulting functionality
> already available via CTV. As far as I can tell, CSFS is one of the least
> controversial opcodes proposed in a long time and just seems to be an
> all-around win with no risks / trade-offs, so why not bundle it in?
>
> I'm not sure how to parse Antoine's claim that CTV+CSFS doesn't enable
> vaults given that there has already been a CTV vault client proof of
> concept for 3 years: https://github.com/jamesob/simple-ctv-vault
>
> On Fri, Jun 13, 2025 at 9:07=E2=80=AFAM Antoine Poinsot <darosior@protonm=
ail.com>
> wrote:
>
>> Jameson,
>>
>> Thanks for sharing. Although i grew more skeptical of the reactive
>> security model of vaults as i implemented them in practice for real user=
s,
>> i can appreciate people's mileage may vary.
>>
>> That said, consensus-enforced vaults require a mechanism to forward any
>> amount received on a script A to a pre-committed script B. CTV+CSFS does
>> not enable this, and a primitive that actually does (like CCV) is more
>> controversial because of its potency. I see the CTV+CSFS bundle as
>> maximizing "bang for your buck" in terms of capabilities enabled compare=
d
>> to the accompanying risk. If we do want vaults, then we need to get past
>> the MEVil concerns and much more interesting primitives are actually on =
the
>> table.
>>
>> I also appreciate that CTV is nice to have for CCV vaults, but a
>> potential future use case that is not enabled by one proposal cannot be
>> used to motivate said proposal.
>>
>> Best,
>> Antoine Poinsot
>> On Friday, June 13th, 2025 at 7:15 AM, Jameson Lopp <
>> jameson.lopp@gmail.com> wrote:
>>
>> > Unlike a generic "We Want Things" sign-on letter, individual messages
>> indicating desire to utilize features is way more compelling.
>>
>> Then I submit my essay from 2 years ago (
>> https://blog.casa.io/why-bitcoin-needs-covenants/) and will quote myself=
:
>>
>> "There are clearly a LOT of use cases that could potentially be unlocked
>> with the right kind of covenant implementation. Personally, having spent=
 8
>> years working on high security multi-signature wallets, I'm most interes=
ted
>> in vaults. I believe the value they offer is quite straightforward and i=
s
>> applicable to every single self-custody bitcoin user, regardless of what
>> type of wallet they are running."
>>
>> - Jameson
>>
>> On Thu, Jun 12, 2025 at 6:54=E2=80=AFPM Matt Corallo <lf-lists@mattcoral=
lo.com>
>> wrote:
>>
>>> To be fair to James, in my (luckily rather brief) experience with
>>> Bitcoin-consensus-letter-writing,
>>> its nearly impossible to forge a statement that everyone agrees to that
>>> is consistently interpreted.
>>>
>>> Matt
>>>
>>> On 6/12/25 3:51 PM, Andrew Poelstra wrote:
>>> > Le Thu, Jun 12, 2025 at 02:38:13PM -0400, James O'Beirne a =C3=A9crit=
 :
>>> >>
>>> >> As the person who coordinated the letter, I can say that this is not
>>> an
>>> >> accurate characterization of the signers' intent. Everyone who signe=
d
>>> >> explicitly wants to see the imminent review, integration, and
>>> activation
>>> >> planning for CTV+CSFS specifically. The letter is intentionally
>>> concise to
>>> >> make sure there are no misunderstandings about that.
>>> >>
>>> >> I spoke to each person on the original list of signatories who eithe=
r
>>> did
>>> >> (or didn't) sign and this was made very clear. Some people didn't
>>> sign as a
>>> >> result of what the letter says.
>>> >>
>>> >
>>> > The letter asks Core to "prioritize the review and integration" on an
>>> > accelerated timeline, and that this will "allow" for "activation
>>> planning".
>>> >
>>> > Early drafts of the letter did ask for actual integration and even
>>> > activation, but I did not sign any of those early drafts. It was not
>>> > until the language was weakened to be about priorities and planning
>>> (and
>>> > to be a "respectful ask" rather some sort of demand) that I signed on=
.
>>> >
>>> >
>>> > The letter is concise but unfortunately I think Matt is correct that =
it
>>> > offers a broad range of interpretations, even among the signers.
>>> >
>>> >
>>>
>>> --
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>>> Groups "Bitcoin Development Mailing List" group.
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>>> an email to bitcoindev+unsubscribe@googlegroups.com.
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>>> https://groups.google.com/d/msgid/bitcoindev/f8b37a59-0897-40df-a08e-78=
12c806a716%40mattcorallo.com
>>> .
>>>
>> --
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n
>> email to bitcoindev+unsubscribe@googlegroups.com.
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>> https://groups.google.com/d/msgid/bitcoindev/CADL_X_fxwKLdst9tYQqabUsJgu=
47xhCbwpmyq97ZB-SLWQC9Xw%40mail.gmail.com
>> .
>>
>>
>> --
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>

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<div dir=3D"ltr"><div>I&#39;m struggling to figure out what kind of useful =
&#39;vault&#39; could be constructed from CTV that isn&#39;t equivalent=C2=
=A0to &quot;presign a transaction that sweeps your funds to an emergency ad=
dress&quot;.=C2=A0 Can someone clue me in?</div><div><br></div><div>It migh=
t be helpful to point to examples of where similar techniques are used in o=
ther blockchains that=C2=A0already=C2=A0facilitate their construction.=C2=
=A0 This isn&#39;t bitcoin-twitter,=C2=A0 it&#39;s permissible=C2=A0to obse=
rve some other system being used in useful ways...</div><div><br></div><div=
><br></div><div><br></div><div><br></div></div><br><div class=3D"gmail_quot=
e gmail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">On Sat, Jun =
14, 2025 at 2:08=E2=80=AFPM Jameson Lopp &lt;<a href=3D"mailto:jameson.lopp=
@gmail.com">jameson.lopp@gmail.com</a>&gt; wrote:<br></div><blockquote clas=
s=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid r=
gb(204,204,204);padding-left:1ex"><div dir=3D"ltr">Casa (and many other com=
panies focused on custody products) would love to see vaulting functionalit=
y. I don&#39;t think any of us are too hung up on the details of the partic=
ular implementation - we would rather have a &quot;good&quot; tool than not=
 have any tool because consensus has not been achieved for a &quot;perfect&=
quot; solution.<div><br></div><div>What is the problem that makes vaults de=
sirable? It&#39;s frankly because there&#39;s no such thing as perfect secu=
rity. Even if one designs an architecture that is nearly perfectly secure a=
gainst external threats, the issue of internal threats (such as oneself, vi=
a social engineering) will remain. The ability to require high value funds =
to sit in a &quot;quarantine / cooldown&quot; address for some period of ti=
me before they can be sent to an arbitrary address enables additional secur=
ity measures a la watchtowers to be designed. Being your own bank is still =
an incredibly scary proposition because it&#39;s quite difficult to design =
custody solutions that tolerate failures without leading to catastrophic lo=
ss. The more tools that custody application engineers have available to the=
m, the more guardrails we can build into wallet software, and thus hopefull=
y the more comfortable we can make the general public with the idea of taki=
ng on the responsibility of self custody.</div><div><br></div><div>To be cl=
ear, I&#39;m not aware of CSFS improving the vaulting functionality already=
 available via CTV. As far as I can tell, CSFS is one of the least controve=
rsial opcodes proposed in a long time and just seems to be an all-around wi=
n with no risks / trade-offs, so why not bundle it in?</div><div><br></div>=
<div>I&#39;m not sure how to parse Antoine&#39;s claim that CTV+CSFS doesn&=
#39;t enable vaults given that there has already been a CTV vault client pr=
oof of concept for 3 years: <a href=3D"https://github.com/jamesob/simple-ct=
v-vault" target=3D"_blank">https://github.com/jamesob/simple-ctv-vault</a><=
/div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_a=
ttr">On Fri, Jun 13, 2025 at 9:07=E2=80=AFAM Antoine Poinsot &lt;<a href=3D=
"mailto:darosior@protonmail.com" target=3D"_blank">darosior@protonmail.com<=
/a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0=
px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><=
div style=3D"font-family:Arial,sans-serif;font-size:14px">Jameson,</div><di=
v style=3D"font-family:Arial,sans-serif;font-size:14px"><br></div><div styl=
e=3D"font-family:Arial,sans-serif;font-size:14px">Thanks for sharing. Altho=
ugh i grew more skeptical of the reactive security model of vaults as i imp=
lemented them in practice for real users, i can appreciate people&#39;s mil=
eage may vary.</div><div style=3D"font-family:Arial,sans-serif;font-size:14=
px"><br></div><div style=3D"font-family:Arial,sans-serif;font-size:14px">Th=
at said, consensus-enforced vaults require a mechanism to forward any amoun=
t received on a script A to a pre-committed script B. CTV+CSFS does not ena=
ble this, and a primitive that actually does (like CCV) is more controversi=
al because of its potency. I see the CTV+CSFS bundle as maximizing &quot;ba=
ng for your buck&quot; in terms of capabilities enabled compared to the acc=
ompanying risk. If we do want vaults, then we need to get past the MEVil co=
ncerns and much more interesting primitives are actually on the table.<br><=
/div><div style=3D"font-family:Arial,sans-serif;font-size:14px"><br></div><=
div style=3D"font-family:Arial,sans-serif;font-size:14px">I also appreciate=
 that CTV is nice to have for CCV vaults, but a potential future use case t=
hat is not enabled by one proposal cannot be used to motivate said proposal=
.</div><div style=3D"font-family:Arial,sans-serif;font-size:14px"><br></div=
><div style=3D"font-family:Arial,sans-serif;font-size:14px">Best,<br>Antoin=
e Poinsot<br></div><div>
        On Friday, June 13th, 2025 at 7:15 AM, Jameson Lopp &lt;<a href=3D"=
mailto:jameson.lopp@gmail.com" target=3D"_blank">jameson.lopp@gmail.com</a>=
&gt; wrote:<br>
        <blockquote type=3D"cite">
            <div dir=3D"ltr">&gt; Unlike a generic &quot;We Want Things&quo=
t; sign-on letter, individual messages indicating desire to utilize feature=
s is way more compelling.<div><br></div><div>Then I submit my essay from 2 =
years ago (<a href=3D"https://blog.casa.io/why-bitcoin-needs-covenants/" re=
l=3D"noreferrer nofollow noopener" target=3D"_blank">https://blog.casa.io/w=
hy-bitcoin-needs-covenants/</a>) and will quote myself:</div><div><br></div=
><div>&quot;There are clearly a LOT of use cases that could potentially be =
unlocked with the right kind of covenant implementation. Personally, having=
 spent 8 years working on high security multi-signature wallets, I&#39;m mo=
st interested in vaults. I believe the value they offer is quite straightfo=
rward and is applicable to every single self-custody bitcoin user, regardle=
ss of what type of wallet they are running.&quot;</div><div><br></div><div>=
- Jameson</div></div><br><div class=3D"gmail_quote"><div class=3D"gmail_att=
r" dir=3D"ltr">On Thu, Jun 12, 2025 at 6:54=E2=80=AFPM Matt Corallo &lt;<a =
href=3D"mailto:lf-lists@mattcorallo.com" rel=3D"noreferrer nofollow noopene=
r" target=3D"_blank">lf-lists@mattcorallo.com</a>&gt; wrote:<br></div><bloc=
kquote style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,=
204);padding-left:1ex" class=3D"gmail_quote">To be fair to James, in my (lu=
ckily rather brief) experience with Bitcoin-consensus-letter-writing, <br>
its nearly impossible to forge a statement that everyone agrees to that is =
consistently interpreted.<br>
<br>
Matt<br>
<br>
On 6/12/25 3:51 PM, Andrew Poelstra wrote:<br>
&gt; Le Thu, Jun 12, 2025 at 02:38:13PM -0400, James O&#39;Beirne a =C3=A9c=
rit :<br>
&gt;&gt;<br>
&gt;&gt; As the person who coordinated the letter, I can say that this is n=
ot an<br>
&gt;&gt; accurate characterization of the signers&#39; intent. Everyone who=
 signed<br>
&gt;&gt; explicitly wants to see the imminent review, integration, and acti=
vation<br>
&gt;&gt; planning for CTV+CSFS specifically. The letter is intentionally co=
ncise to<br>
&gt;&gt; make sure there are no misunderstandings about that.<br>
&gt;&gt;<br>
&gt;&gt; I spoke to each person on the original list of signatories who eit=
her did<br>
&gt;&gt; (or didn&#39;t) sign and this was made very clear. Some people did=
n&#39;t sign as a<br>
&gt;&gt; result of what the letter says.<br>
&gt;&gt;<br>
&gt; <br>
&gt; The letter asks Core to &quot;prioritize the review and integration&qu=
ot; on an<br>
&gt; accelerated timeline, and that this will &quot;allow&quot; for &quot;a=
ctivation planning&quot;.<br>
&gt; <br>
&gt; Early drafts of the letter did ask for actual integration and even<br>
&gt; activation, but I did not sign any of those early drafts. It was not<b=
r>
&gt; until the language was weakened to be about priorities and planning (a=
nd<br>
&gt; to be a &quot;respectful ask&quot; rather some sort of demand) that I =
signed on.<br>
&gt; <br>
&gt; <br>
&gt; The letter is concise but unfortunately I think Matt is correct that i=
t<br>
&gt; offers a broad range of interpretations, even among the signers.<br>
&gt; <br>
&gt; <br>
<br>
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</blockquote></div>

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