Subject: Re: [bitcoindev] [Proposal] 64-bit arithmetic in Script

From: Martin Habovštiak <[email-masked]>
Date: Mon, 12 May 2025 16:32:08 -0300

Hi,

the proposal seems to be quite confused about how it's going to do that. It
mentions upgrading existing opcodes, which is a hardfork, not soft fork, at
least without using a different leaf version. But it also mentions
OP_SUCCESSX which are different opcodes. I think it needs some analysis.
(leaf version seems better intuitively)

I'd also love to see analysis why stop at 64 bits and not go all the way to
256 which could be useful for cryptography.

Anyway, pushing amounts on the stack would be great. Though I'm surprised
you're only proposing the sum, not individual outputs. Why?

Good luck!

Martin

Dňa po 12. 5. 2025, 14:21 Chris Stewart <[email-masked]>
napísal(a):

> This soft fork proposal extends the range of numeric operands in Script
> from -2^31+1 to 2^31-1, to -2^63+1 to 2^63-1. It further expands the
> result range for arithmetic operations from -2^63 to 2^63-1, to -2^127 to
> 2^127- 1.
>
> All existing opcodes[1
> <https://github.com/Christewart/bips/blob/2025-03-17-64bit-pt2/bip-XXXX.mediawiki#cite_note-1>
> ] that interpret stack elements as numbers are upgraded to support 64-bit
> parameters.
>
> The existing number encoding format[2
> <https://github.com/Christewart/bips/blob/2025-03-17-64bit-pt2/bip-XXXX.mediawiki#cite_note-2>
> ] and arithmetic semantics[3
> <https://github.com/Christewart/bips/blob/2025-03-17-64bit-pt2/bip-XXXX.mediawiki#cite_note-3>
> ] from the original Bitcoin implementation are preserved, while enhancing
> the supported precision.
>
>
> https://github.com/Christewart/bips/blob/2025-03-17-64bit-pt2/bip-XXXX.mediawiki
>
> The purpose for this BIP is to lay the groundwork for introducing amounts
> into Script. This document takes no opinion on how this is done.
>
> I've prototyped a few different proposals now introducing amount locks
> into Script[0][1] and feel like this proposal is stable enough for serious
> review.
>
> -Chris
>
> [0] - https://delvingbitcoin.org/t/op-inout-amount/549/4?u=chris_stewart_5
>
> [1] - https://delvingbitcoin.org/t/op-inout-amount/549/5?u=chris_stewart_5
>
>
>
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