Re: [bitcoin-dev] Relaxing minimum non-witness transaction size policy restriction

[Greg Sanders <gsanders87@gmail.com>]

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Propagation of these kinds of transactions will be hampered until <merge
version in core> becomes 10%+ of the network or so, like any other policy
relaxation.

On Tue, Oct 11, 2022 at 9:08 AM KING JAMES HRMH <willtech@live.com.au>
wrote:

> I am reading between the lines, wouldn't that mean an older client like
> v0.18 may not be able to receive a transaction from a newer client if it
> has to validate 85 non-witness serialized bytes? If so we should not
> concern but retain the backward compatibility especially since this was for
> a vulnerability? I have not checked to code to see what it does.
>
> KING JAMES HRMH
>
> Get Outlook for Android <https://aka.ms/AAb9ysg>
> ------------------------------
> *From:* bitcoin-dev <bitcoin-dev-bounces@lists.linuxfoundation.org> on
> behalf of Greg Sanders via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org>
> *Sent:* Tuesday, October 11, 2022 11:50:07 PM
> *To:* Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>
> *Subject:* [bitcoin-dev] Relaxing minimum non-witness transaction size
> policy restriction
>
> Hello fellow Bitcoiners,
>
> After looking at some fairly exotic possible transaction types, I ran into
> the current policy limit requiring transactions to be 85 non-witness
> serialized bytes. This was introduced as a covert fix to policy fix
> for CVE-2017-12842. Later the real motivation was revealed, but the
> "reasonable" constant chosen was not.
>
> I'd like to propose relaxing this to effectively the value BlueMatt
> proposed in the Great Consensus Cleanup: 65 non-witness bytes. This would
> allow a single input, single output transaction with 4 bytes of OP_RETURN
> padding, rather than padding out 21 bytes to get to p2wpkh size.
>
> The alternative would be to also allow anything below 64 non-witness
> bytes, but this seems fraught with footguns for a few bytes gain.
>
> The PR is here with more relevant background and alternatives included in
> the thread:
> https://github.com/bitcoin/bitcoin/pull/26265
>
> Please let us know if there's a fundamental issue with this approach, or
> any other feedback.
>
> Best,
> Greg
>

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