Date: Sat, 07 May 2022 22:40:10 +0000
To: =?utf-8?Q?Jorge_Tim=C3=B3n?= <jtimon@jtimon.cc>,
 Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
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Subject: Re: [bitcoin-dev] CTV BIP Meeting #8 Notes
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Good morning Jorge,

> I think people may be scared of potential attacks based on covenants. For=
 example, visacoin.
> But there was a thread with ideas of possible attacks based on covenants.
> To me the most scary one is visacoin, specially seeing what happened in c=
anada and other places lately and the general censorship in the west, the s=
upposed war on "misinformation" going on (really a war against truth imo, b=
ut whatever) it's getting really scary. But perhaps someone else can be mor=
e scared about a covenant to add demurrage fees to coins or something, I do=
n't know.
> https://bitcointalk.org/index.php?topic=3D278122

This requires *recursive* covenants.

At the time the post was made, no distinction was seen between recursive an=
d non-recursive covenants, which is why the post points out that covenants =
suck.
The idea then was that anything powerful enough to provide covenants would =
also be powerful enough to provide *recursive* covenants, so there was no d=
istinction made between recursive and non-recursive covenants (the latter w=
as thought to be impossible).

However, `OP_CTV` turns out to enable sort-of covenants, but by constructio=
n *cannot* provide recursion.
It is just barely powerful enough to make a covenant, but not powerful enou=
gh to make *recursive* covenants.

That is why today we distinguish between recursive and non-recursive covena=
nt opcodes, because we now have opcode designs that provides non-recursive =
covenants (when previously it was thought all covenant opcodes would provid=
e recursion).

`visacoin` can only work as a recursive covenant, thus it is not possible t=
o use `OP_CTV` to implement `visacoin`, regardless of your political views.

(I was also misinformed in the past and ignored `OP_CTV` since I thought th=
at, like all the other covenant opcodes, it would enable recursive covenant=
s.)


Regards,
ZmnSCPxj