Hi Daniel,

From my understanding of GAP600, you're operating a zero-conf risk analysis
business, which is integrated and leveraged by payment processors/liquidity
providers and merchants. A deployment of fullrbf by enough full-node
operators and a subset of the mining hashrate would lower the cost of
double-spend attack by lamda users, therefore increasing the risk exposure
of your users. This increased risk exposure could lead you to alter the
acceptance of incoming zero-conf transactions, AFAICT in a similar
reasoning as exposed by Bitrefill earlier this year [0].

About the statistics you're asking for considerations, few further
questions, on those 1.5M transactions per month, a) how many are
Bitcoin-only (as I understand to be multi-cryptocurrencies), b) how many
are excluded from zeroconf due to factors like RBF, long-chain of
unconfirmed ancestors or too high-value and c) what has been the average
feerate (assuming a standard size of 200 bytes) ?

My personal position on fullrbf is still the same as expressed in #26525
[1]. As a community, I think we still don't have conceptual consensus on
deploying full-rbf, neither to remove it. In the direction of removing the
current option from Bitcoin Core, I think the prerequisite to address are
the qualification of enough economic flows at risk and the presence of a
sizable loss in miners income. Beyond that, I think there is still the open
question if we (we, as the Bitcoin protocol development community, with all
its stakeholders) should restrain user choice in policy settings in the
name of preserving mining income and established use-case stability.

To recall, the original technical motivation of this option, and the wider
smoother deployment was to address a DoS vector affecting another class of
use-case: multi-party transactions like coinjoin and contracting protocols
like Lightning [2] [3]. All of them expect to generate economic flows and
corresponding mining income. Since then, alternative paths to solve this
DoS vector have been devised, all with their own trade-offs and conceptual
issues [4] [5].

Best,
Antoine

[0]
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-October/021070.html
[1] https://github.com/bitcoin/bitcoin/pull/26525#issuecomment-1319499006
[2]
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-June/020557.html
[3]
https://lists.linuxfoundation.org/pipermail/lightning-dev/2021-May/003033.html
[4]
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-October/021135.html
[5]
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-November/021144.html

Le jeu. 1 déc. 2022 à 07:32, Daniel Lipshitz via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> a écrit :

> HI All
>
> I am the CEO of GAP600. We guarantee zero confirmed Bitcoin and other
> crypto  transactions, BTC is a primary part of our business. Our guarantee
> enables our customers to recognise zero-conf deposits. We reimburse our
> clients value of the trx should we get it wrong and a transaction we
> confirmed gets double spent.
>
> Should full RBF become default enabled and significantly adopted this
> would have a major impact on the capacity to accept zerof confs on mainnet.
> With the end result being this use case will be forced to move to a
> different chain, with lightning being just another option.
>
> I wanted to share some statistics about how significant this use case is.
> GAP600 clients are primarily payment processors and non custodial
> liquidity providers; you can see some of our clients on our site
> www.gap600.com. There are also merchants who have developed their own
> tools so GAP600 statistics are only a subset of the full use case.
>
> I do not know of any wallet, exchange or custodian who accepts zero conf
> without having some sort of solution in place. The market seems to be fully
> aware of the risks of zero-conf. The opt-RBF seems to be a solution which
> gives a clear free choice for actors.
>
> Statistics for consideration as a sample of the zero conf use case -
>
>
>    1. As of end of Nov 2022 - GAP600 has processed i.e responded to circa
>    15M transactions
>    2. These transactions have a cumulative value of 2.3B USD value.
>    3. We currently are seeing circa 1.5M transactions queired per month.
>
>
> It's a sizable amount of trxs on mainet and we are by no means the full
> market of platforms accepting zero-conf.  I realise there are other
> considerations which BTC has,  I would urge you to take into account the
> major risk being placed on this significant market share when deciding to
> make this feature default enabled and encouraging full adoption.
>
> Thank you for your consideration
> Daniel
> ________________________________
>
> Daniel Lipshitz
> GAP600| www.gap600.com
>
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