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From: "Russell O'Connor" <roconnor@blockstream.com>
Date: Sat, 29 Jan 2022 12:14:43 -0500
Message-ID: <CAMZUoKki0M6jvgdtQLETa2fjYJkCqwWaj1k1WSSa=e8DJ8tPxA@mail.gmail.com>
To: Jeremy Rubin <j@rubin.io>
Content-Type: multipart/alternative; boundary="000000000000b042f005d6bbb006"
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] TXHASH + CHECKSIGFROMSTACKVERIFY in lieu of CTV
and ANYPREVOUT
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The hash would normally also cover the hash flags in use, and would be
different in those two cases.
But yes, it seems at the last minute I did include a suggestion to disable
covering the flag themselves in the hash and appear to have accidentally
allowed for recursive covenants (a common occurrence when designing
opcodes).
On Sat, Jan 29, 2022 at 12:01 PM Jeremy Rubin <j@rubin.io> wrote:
>
>
>
>> Perhaps there is some misunderstanding. TXHASH + CSFSV doesn't allow for
>> complex or recursive covenants. Typically CAT is needed, at minimum, to
>> create those sorts of things. TXHASH still amounts to deploying a
>> non-recursive covenant construction.
>>
>>
> This seems false to me.
>
> <Only hash a single input scriptpubkey> txhash <only hash a single output
> scriptpubkey> txhash equalverify
>
> Is that not a recursive covenant? With a little extra work you can also
> control for amounts and stuff.
>
>
>
>>
--000000000000b042f005d6bbb006
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><div></div><div>The hash would normally also cover the has=
h flags in use, and would be different in those two cases.</div><div><br></=
div><div>But yes, it seems at the last minute I did include a suggestion to=
disable covering the flag themselves in the hash and appear to have accide=
ntally allowed for recursive covenants (a common occurrence when designing =
opcodes).<br></div><div><br><div class=3D"gmail_quote"><div dir=3D"ltr" cla=
ss=3D"gmail_attr">On Sat, Jan 29, 2022 at 12:01 PM Jeremy Rubin <<a href=
=3D"mailto:j@rubin.io">j@rubin.io</a>> wrote:<br></div><blockquote class=
=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rg=
b(204,204,204);padding-left:1ex"><div dir=3D"auto"><div><div class=3D"gmail=
_quote"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex=
;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">=
<div class=3D"gmail_quote"><div></div></div></div></blockquote></div></div>=
<div dir=3D"auto"><br></div><div dir=3D"auto"><br></div><div dir=3D"auto"><=
div class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"margin=
:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"=
><div dir=3D"ltr"><div class=3D"gmail_quote"><div><br></div><div>Perhaps th=
ere is some misunderstanding.=C2=A0 TXHASH=C2=A0+ CSFSV doesn't allow f=
or complex or recursive covenants.=C2=A0 Typically CAT is needed, at minimu=
m, to create those sorts of things.=C2=A0 TXHASH still amounts to deploying=
a non-recursive covenant construction.<br></div><div><br></div><div></div>=
</div></div></blockquote></div></div><div dir=3D"auto"><div class=3D"gmail_=
quote"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;=
border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr"><=
div class=3D"gmail_quote"><div></div></div></div></blockquote></div></div><=
div dir=3D"auto"><br></div><div dir=3D"auto">This seems false to me.=C2=A0<=
/div><div dir=3D"auto"><br></div><div dir=3D"auto"><Only hash a single i=
nput scriptpubkey> txhash <only hash a single output scriptpubkey>=
txhash equalverify</div><div dir=3D"auto"><br></div><div dir=3D"auto">Is t=
hat not a recursive covenant? With a little extra work you can also control=
for amounts and stuff.</div><div dir=3D"auto"><br></div><div dir=3D"auto">=
<br></div><div dir=3D"auto"><div class=3D"gmail_quote"><blockquote class=3D=
"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(2=
04,204,204);padding-left:1ex"><div dir=3D"ltr"><div class=3D"gmail_quote"><=
div><br></div></div></div>
</blockquote></div></div></div>
</blockquote></div></div></div>
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