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From: Jeremy <jlrubin@mit.edu>
Date: Sun, 4 Jul 2021 10:30:18 -0700
Message-ID: <CAD5xwhgtsqAX99NJRU6t-s14aF7frGZxFCL3-c9iBOYrkN_A_w@mail.gmail.com>
To: "Russell O'Connor" <roconnor@blockstream.com>
Content-Type: multipart/alternative; boundary="00000000000096a79605c64f8b10"
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] CHECKSIGFROMSTACK/{Verify} BIP for Bitcoin
Precedence: list

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I don't really see the point of CHECKSIGFROMSTACKADD since it's not bound
to the txdata? When might you use this?

And yes -- "Add OP_CHECKSIGFROMSTACK and OP_CHECKSIGFROMSTACKVERIFY to
follow the semantics from bip340-342 when witness program is v1." is a bit
light on detail for what the BIP would end up looking like. If you're able
to open up the design process a bit more on that it would be good as I
think there are some topics worth discussing at large before things proceed
with Elements (assuming feature compatibility remains a goal).

The non-prehashed argument seems OK (at the cost of an extra byte...) but
are there specific applications for !=32 arguments? I can't think of a
particular one beyond perhaps efficiency. Can we safely use 0-520 byte
arguments?

Also do you have thoughts on the other questions i posed above? E.g.
splitting R/S could be helpful w/o CAT.

--
@JeremyRubin <https://twitter.com/JeremyRubin>
<https://twitter.com/JeremyRubin>


On Sat, Jul 3, 2021 at 1:13 PM Russell O'Connor <roconnor@blockstream.com>
wrote:

> There is one line written at
> https://github.com/ElementsProject/elements/pull/949/files#r660130155.
>

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<div dir=3D"auto"><div dir=3D"ltr"><div dir=3D"ltr">I don&#39;t really see =
the point of CHECKSIGFROMSTACKADD since it&#39;s not bound to the txdata? W=
hen might you use this?<br><br>And yes -- &quot;Add OP_CHECKSIGFROMSTACK an=
d OP_CHECKSIGFROMSTACKVERIFY to follow the semantics from bip340-342 when w=
itness program is v1.&quot; is a bit light on detail for what the BIP would=
 end up looking like. If you&#39;re able to open up the des<span class=3D"g=
mail_default" style=3D"">ign process a bit more on that it would be good as=
 I think there are some topics worth discussing at large before things proc=
eed with Elements (assuming feature compatibility remains a goal).</span></=
div><div dir=3D"ltr"><br></div><div dir=3D"ltr"><div class=3D"gmail_default=
" style=3D"">The non-prehashed=C2=A0argument seems OK (at the cost of an ex=
tra byte...) but are there specific applications for !=3D32 arguments? I ca=
n&#39;t think of a particular one beyond perhaps efficiency. Can we safely =
use 0-520 byte arguments?</div><div class=3D"gmail_default" style=3D""><br>=
</div><div class=3D"gmail_default" style=3D"">Also do you have thoughts on =
the other questions i posed above? E.g. splitting R/S could be helpful w/o =
CAT.</div><br></div><div dir=3D"ltr">--<br><div><div dir=3D"ltr" data-smart=
mail=3D"gmail_signature"><div dir=3D"ltr"><a href=3D"https://twitter.com/Je=
remyRubin" target=3D"_blank" rel=3D"noreferrer">@JeremyRubin</a><a href=3D"=
https://twitter.com/JeremyRubin" target=3D"_blank" rel=3D"noreferrer"></a><=
/div></div></div><br></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" =
class=3D"gmail_attr">On Sat, Jul 3, 2021 at 1:13 PM Russell O&#39;Connor &l=
t;<a href=3D"mailto:roconnor@blockstream.com" target=3D"_blank" rel=3D"nore=
ferrer">roconnor@blockstream.com</a>&gt; wrote:<br></div><blockquote class=
=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left-width:1px;bo=
rder-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">=
<div dir=3D"ltr"><div>There is one line written at <a href=3D"https://githu=
b.com/ElementsProject/elements/pull/949/files#r660130155" target=3D"_blank"=
 rel=3D"noreferrer">https://github.com/ElementsProject/elements/pull/949/fi=
les#r660130155</a>.</div></div>
</blockquote></div></div></div>

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