Hey all,
I’m interested in sharing a different idea regarding legacy signatures in QRAMP. Instead of rendering ECDSA spends useless after a certain point, what if we put them into a quarantine mode? This way, legacy UTXOs could still be spendable after PQ activation, but only through a two-phase commit then spend flow. It’s meant to prevent any dodgy stuff even if the private key is easily derived post-pubkey reveal.
That’s an interesting take, but moving to a two-phase system adds a lot of complexity and requires a new opcode. If the checks are simple enough and won’t backfire, then I’m all ears. But if it turns into a situation where every transaction needs a bunch of added proofs, the community won’t be happy about it.
The big issue here is incentives. Phase 1 might be fine, but Phase 2 really depends on people wanting to keep those commitment proofs, and Bitcoin usually doesn’t favor anything that’s not beneficial right away. Maybe this is more about keeping legacy keys secure first, with post-quantum protection as a nice side effect?
Appreciate your thoughts! You’re spot on about the ‘backpack’ issue, but I see these two-phase transactions as a secondary option. This is mainly about getting funds from old addresses that weren't moved to new post-quantum addresses when migration came around. Right now, some ideas floating around could leave bitcoins on those old addresses completely stranded. No one wants that, or it could create a split in the chain.
Sounds kind of similar to what Tadge Dryja suggested in another thread.
I remember the mailing list entry from that. Your idea might even be an improvement on his. His relied on looking up older transactions, but maybe there’s a better way with your approach.