From: Salvatore Ingala <salvatore.ingala@gmail•com>
To: "Johan Torås Halseth" <johanth@gmail•com>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Concrete MATT opcodes
Date: Wed, 9 Aug 2023 10:38:48 +0200 [thread overview]
Message-ID: <CAMhCMoEoSiGPBczQerBe1TDJvo2Gkf4gbXOPUayKkNLsC_y4SQ@mail.gmail.com> (raw)
In-Reply-To: <CAD3i26AxcRCewX7vt5KV9vQp_mD=DaH1GEmqQQ1Ct8v_oW-WXQ@mail.gmail.com>
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Hi Johan,
Thanks a lot for the comments, and the independent implementation!
> - For the opcode parameter ordering, it feels unnatural for the two
> tweaks (data, taptree) to be separated by the internal key. A more
> natural ordering of parameters IMO would be (of course this is all
> subjective):
> <data> <taptree> <internalkey> <index> <flags> OP_CCV.
>
> If you disagree, I would love some rationale for the ordering you
> chose! (looks like you also changed it again after your last post?).
The main concern for the reordering was to put <data> at the bottom,
as that's typically passed via the witness stack.
I put the <index> right next, as I suspect there are use cases for
specifying via the witness what is the input index where a certain
(CCV-encumbered) UTXO is to be found, or which output should funds
be sent to, instead of hard-coding this in the script. This might
help in designing contracts that are more flexible in the way they
are spent, for example by allowing batching their transactions.
Instead, I expect the other parameters to almost always be hardcoded,
or propagated from the current input with the <-1> special values.
I agree that your ordering is more aesthetically pleasing, though.
> I'm wondering what other use cases you had in mind for the deferred
> output amount check? Maybe I have missed something, but if not it
> would perhaps be better to leave out the amount preservation check, or
> go the extra mile and propose a more powerful amount introspection
> machinery.
Yes, the deferred output amount check is not enough for coinpools;
however, it comes at no cost if we have a <flags> parameter anyway,
as OP_2 (value for CCV_IGNORE_OUTPUT_AMOUNT) is a single byte opcode.
The intent of preserving amounts for many-to-one contracts (vaults),
or the one-to-one cases (channels, any 2-party contract, etc.) seems
common enough to deserve 1 bit in the flags, IMHO.
Efforts to define and add explicit introspection to cover your
(exciting!) use cases can proceed independently, but I don't think
they would nullify the advantages of this (optional) feature of CCV.
Best,
Salvatore
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next prev parent reply other threads:[~2023-08-09 8:39 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-30 21:37 Salvatore Ingala
2023-08-06 20:13 ` David A. Harding
2023-08-07 8:31 ` Salvatore Ingala
2023-08-07 11:37 ` Johan Torås Halseth
2023-08-09 8:38 ` Salvatore Ingala [this message]
2023-08-14 3:00 ` Antoine Riard
2023-08-14 14:07 ` symphonicbtc
2023-08-18 20:12 ` Antoine Riard
2023-08-19 23:11 ` symphonicbtc
2023-09-13 20:25 ` Antoine Riard
2023-08-18 15:08 ` Salvatore Ingala
2023-09-15 0:23 ` Antoine Riard
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