From: Andrew Poelstra <apoelstra@wpsoftware•net>
To: Weikeng Chen <weikeng.chen@l2iterative•com>
Cc: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: Re: [bitcoindev] Difficulty in emulating "weaker" OP_SUCCESS and why it should be a real opcode
Date: Mon, 9 Dec 2024 19:08:51 +0000 [thread overview]
Message-ID: <Z1dAQ8pSIqn8XA56@camus> (raw)
In-Reply-To: <ebd77d82-96ab-4530-909a-d085378b9868n@googlegroups.com>
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On Mon, Dec 09, 2024 at 05:27:54AM -0800, Weikeng Chen wrote:
> When I am implementing fraud proofs in Bitcoin script, I find it useful to
> have an opcode "OP_SUCCESS" that will mark the execution to be successful
> without running the rest of the script, if this opcode is being executed.
> This is useful for writing code for fraud proofs such as BitVM, where the
> verifier wins if it finds one mismatch, and the verifier does not need to
> show the other mismatches.
>
> This OP_SUCCESS is weaker version of the OP_SUCCESSx in the Taproot
> upgrade, which marks the execution as successful for the mere presence of
> OP_SUCCESSx anywhere in the script. Rusty Russell in a 2023 article,
> "Covenants: Examining ScriptPubkeys in Bitcoin Script", also mentioned
> about the usefulness of such an opcode.
>
> Of course, this opcode can be emulated, and one can rewrite the existing
> script in a way to realize the same functionality without adding a new
> opcode to Bitcoin.
>
> The problem is that such rewriting is indeed fairly complicated. For
> example, say that we have the following program.
>
> <snip>
I raised the question on IRC about why the existing SUCCESSx codes work
the way they do, and got several good anwsers that you can read here
https://gnusha.org/bitcoin-wizards/2024-12-09.log
In short, for purpose of softforking upgrade mechanism, the existing
SUCCESS codes give us way more freedom of action.
But it sounds like you want a "weak SUCCESS" opcode in order to use the
success semantics, not as an upgrade mechanism. Maybe it makes sense to
propose that one of the existing OP_SUCCESSx opcodes should be
softforked to become OP_WEAK_SUCCESS?
--
Andrew Poelstra
Director, Blockstream Research
Email: apoelstra at wpsoftware.net
Web: https://www.wpsoftware.net/andrew
The sun is always shining in space
-Justin Lewis-Webster
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next prev parent reply other threads:[~2024-12-09 19:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-09 13:27 Weikeng Chen
2024-12-09 19:08 ` Andrew Poelstra [this message]
2024-12-09 22:06 ` Brandon Black
[not found] ` <87ttbccrql.fsf@rustcorp.com.au>
2024-12-12 3:17 ` Weikeng Chen
2024-12-12 5:49 ` Brandon Black
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