Subject: Re: [bitcoin-dev] Debate: 64 bytes in OP_RETURN VS taproot OP_FALSE OP_IF OP_PUSH

From: Aymeric Vitte <[email-masked]>
Date: Thu, 2 Feb 2023 12:45:42 +0100

As far as I can read nobody replied to the initial question: what is
considered as good/best practice to store in Bitcoin?

Reiterating my question: what are the current rules for OP_RETURN, max
size and number of OP_RETURN per tx

Le 02/02/2023 à 12:22, Peter Todd via bitcoin-dev a écrit :
> On Wed, Feb 01, 2023 at 02:02:41PM +0000, Andrew Poelstra wrote:
>> On Tue, Jan 31, 2023 at 09:07:16PM -0500, Peter Todd via bitcoin-dev wrote:
>>>
>>> On January 31, 2023 7:46:32 PM EST, Christopher Allen via bitcoin-dev <[email-masked]> wrote:
>>>> All other things being equal, which is better if you need to place a
>>>> 64-bytes into the Bitcoin blockchain? A traditional OP_RETURN or a spent
>>>> taproot transaction such as:
>>>>
>>>> OP_FALSE
>>>> OP_IF
>>>> OP_PUSH my64bytes
>>>> OP_ENDIF
>>> What's wrong with OpPush <data> OpDrop?
>>>
>> This is a technical nit, but the reason is that <data> is limited to 520
>> bytes (and I believe, 80 bytes by standardness in Taproot), so if you
>> are pushing a ton of data and need multiple pushes, it's more efficient
>> to use FALSE IF ... ENDIF since you avoid the repeated DROPs.
> Yes, for more than 520 bytes you need to wrap the push in an IF/ENDIF so it's
> not executed. But in this example we're just talking about 64 bytes, so that
> limit isn't relevant and OpPush <data> OpDrop should be sufficient.
>
> Specifically for more than 520 bytes you run into the the
> MAX_SCRIPT_ELEMENT_SIZE check in script/interpreter.cpp, which applies to all
> scripts regardless of standardness at script execution:
>
>            //
>            // Read instruction
>            //
>            if (!script.GetOp(pc, opcode, vchPushValue))
>                return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
>            if (vchPushValue.size() > MAX_SCRIPT_ELEMENT_SIZE)
>                return set_error(serror, SCRIPT_ERR_PUSH_SIZE);
>
>
>
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