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From: James MacWhyte <macwhyte@gmail.com>
Date: Mon, 26 Jul 2021 22:08:09 +0100
Message-ID: <CAH+Axy7cPufMUCMQbCz2MUgRqQbgenAozPBFD8kPYrSjwcRG8w@mail.gmail.com>
To: Billy Tetrud <billy.tetrud@gmail.com>, 
 Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary="000000000000085c3305c80d285b"
Subject: Re: [bitcoin-dev] Covenant opcode proposal OP_CONSTRAINDESTINATION
 (an alternative to OP_CTV)
Precedence: list

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Hi Billy!

See above, but to break down that situation a bit further, these are the
> two situations I can think of:
>
>    1. The opcode limits user/group A to send the output to user/group B
>    2. The opcode limits user A to send from one address they own to
>    another address they own.
>
> I'm trying to think of a good use case for this type of opcode. In these
examples, an attacker who compromises the key for user A can't steal the
money because it can only be sent to user B. So if the attacker wants to
steal the funds, they would need to compromise the keys of both user A and
user B.

But how is that any better than a 2-of-2 multisig? Isn't the end result
exactly the same?

James

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<div dir=3D"ltr"><div dir=3D"ltr">Hi Billy!</div><div dir=3D"ltr"><br></div=
><div class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"marg=
in:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1e=
x"><div dir=3D"ltr"><div><span style=3D"">See above, but to break down that=
 situation a bit further, these are the two situations I can think of:</spa=
n><br></div><div><div><ol><li style=3D"padding-bottom:0.6001em">The opcode =
limits user/group A to send the output to user/group B</li><li style=3D"pad=
ding-bottom:0.6001em">The opcode limits user A to send from one address the=
y own to another address they own.=C2=A0</li></ol></div></div></div></block=
quote><div><span style=3D"">I&#39;m trying to think of a good use case for =
this type of opcode. In these examples, an attacker who compromises the key=
 for user A can&#39;t steal the money because it can only be sent to user B=
. So if the attacker wants to steal the funds, they would need to compromis=
e the keys of both user A and user B.</span></div><div><span style=3D""><br=
></span></div><div><span style=3D"">But how is that any better than a 2-of-=
2 multisig? Isn&#39;t the end result exactly=C2=A0the same?</span><br></div=
><div><span style=3D""><br></span></div><div><span style=3D"">James</span><=
/div></div></div>

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