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Subject: Re: [bitcoindev] Against Allowing Quantum Recovery of Bitcoin
From: Sjors Provoost <sjors@sprovoost.nl>
In-Reply-To: <912fd35e-02f5-49b5-b373-ca02806d952f@mattcorallo.com>
Date: Tue, 25 Mar 2025 09:16:00 +0100
Cc: Matt Corallo <lf-lists@mattcorallo.com>,
 Jameson Lopp <jameson.lopp@gmail.com>
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Matt Corallo wrote:

>> In that scenario you'd need to use a NUMS point for the key path. Or may=
be that's unsafe, in which case we'd need a new Taproot version without key=
 path support (or BIP360). That's also not a difficult soft fork, but now a=
gain you have something that only a small set of users will want to use.
>>>=20
>>>=20
> A NUMS point does not suffice unless we explicitly soft-fork out spending=
 from that NUMS point (which is, of course, doable).

This could be a solution to the sequencing conundrum that I tried to explai=
n.

Along with the first PCQ scheme for tapscript (script path), we could have =
a soft that disables one or more NUMS points. The latter has zero effect un=
der the current cryptographic assumptions, so it's not confiscatory.

That way people can start using the scheme without having to worry about wh=
ether the community decides to freeze key path spending in time. They'll st=
ill worry about the market value of their coins, but not about whether they=
're going to be the first victim (or the umpteenth victim while everyone is=
 in denial and blames them for poor key management).

- Sjors

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