[bitcoin-dev] Unlimited covenants, was Re: CHECKSIGFROMSTACK/{Verify} BIP for Bitcoin

From: "David A. Harding" <dave@dtrt•org>
To: Jeremy <jlrubin@mit•edu>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: [bitcoin-dev] Unlimited covenants, was Re:  CHECKSIGFROMSTACK/{Verify} BIP for Bitcoin
Date: Sun, 4 Jul 2021 10:32:30 -1000	[thread overview]
Message-ID: <20210704203230.37hlpdyzr4aijiet@ganymede> (raw)
In-Reply-To: <CAD5xwhimPBEV_tLpSPxs9B+XGUhvPx_dnhok=8=hyksyi4=B6g@mail.gmail.com>

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On Sun, Jul 04, 2021 at 11:39:44AM -0700, Jeremy wrote:
> However, I think the broader community is unconvinced by the cost benefit
> of arbitrary covenants. See
> https://medium.com/block-digest-mempool/my-worries-about-too-generalized-covenants-5eff33affbb6
> as a recent example. Therefore as a critical part of building consensus on
> various techniques I've worked to emphasize that specific additions do not
> entail risk of accidentally introducing more than was bargained for to
> respect the concerns of others.

Respecting the concerns of others doesn't require lobotomizing useful
tools.  Being respectful can also be accomplished by politely showing
that their concerns are unfounded (or at least less severe than they
thought).  This is almost always the better course IMO---it takes much
more effort to satisfy additional engineering constraints (and prove to
reviewers that you've done so!) than it does to simply discuss those
concerns with reasonable stakeholders.  As a demonstration, let's look
at the concerns from Shinobi's post linked above:

They seem to be worried that some Bitcoin users will choose to accept
coins that can't subsequently be fungibily mixed with other bitcoins.
But that's already been the case for a decade: users can accept altcoins
that are non-fungible with bitcoins.

They talk about covenants where spending is controlled by governments,
but that seems to me exactly like China's CBDC trial.

They talk about exchanges depositing users' BTC into a covenant, but 
that's just a variation on the classic not-your-keys-not-your-bitcoins
problem.  For all you know, your local exchange is keeping most of its
BTC balance commitments in ETH or USDT.

To me, it seems like the worst-case problems Shinobi describes with
covenants are some of the same problems that already exist with
altcoins.  I don't see how recursive covenants could make any of those
problems worse, and so I don't see any point in limiting Bitcoin's
flexibility to avoid those problems when there are so many interesting
and useful things that unlimited covenants could do.

-Dave

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