From: "'bnv' via Bitcoin Development Mailing List" <bitcoindev@googlegroups.com>
To: "bitcoindev@googlegroups.com" <bitcoindev@googlegroups.com>
Subject: [bitcoindev] QRAMP addition: Alternative to legacy freeze: “quarantine-mode” legacy spends via two-phase destination commitment
Date: Tue, 13 Jan 2026 02:15:58 +0000 [thread overview]
Message-ID: <e2NtSyWxHaZUUHSKA4XYAr8etu7yfXwUTy6gRm456-wWa0UDz_DfoZ9W6ACIVtbMIRjL26yFRCu0iKr5wWfNf0xITLT7EiB-uPYqt2C1e28=@proton.me> (raw)
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Hi Everyone,
I’d like feedback on a concept that I want to frame explicitly as an *alternative* to “freeze/sunset legacy signatures” in QRAMP (Quantum‑Resistant Address Migration Protocol) or similar migration planning.
Instead of making legacy ECDSA spends invalid after a cutoff, we could place them into a **quarantine mode**:
- Legacy UTXOs remain spendable after post-quantum (PQ) activation,
- but only via a **two-phase commit→spend** flow that prevents destination-substitution even if the legacy private key can be derived quickly after pubkey reveal.
High-level:
1) **Commit phase (on-chain):** publish a commitment that binds the eventual spend outputs (preferably the full output set: amounts + scriptPubKeys) and becomes valid only after ≥K confirmations.
2) **Spend phase (on-chain):** a legacy spend is valid only if it presents (a) proof that a matching commitment was mined and is mature, and (b) the spend’s outputs match the committed template.
Key feasibility constraint: this must be **consensus-enforced without historical tx lookups** (pruned nodes / no txindex). So the spend likely needs to carry an SPV-style inclusion proof for the commit (txid + merkle branch to a block header + ≥K depth rule).
A critical UX point is **fee sponsorship**: a receiver/exchange/service can publish the commit tx and pay fees, while the legacy holder authorizes the commitment off-chain (signature over the commitment hash), avoiding the “I can’t safely fee-pay Phase 1” problem.
Short design note + diagram (please replace with your links):
- Markdown:
https://github.com/bnavf/bitcoinqp/blob/main/two_phase_destination_commitment.md
- Diagram:
https://github.com/bnavf/bitcoinqp/blob/main/two_phase_destination_commitment.svg
Questions for the list:
1) Is there an existing proposal that already captures this “quarantine-mode legacy spends” framing?
2) What’s the most reasonable way to do commitment inclusion/maturity proofs without creating an indexer-dependent consensus rule?
3) Is binding the *full output set* sufficient to rule out practical destination-substitution variants?
Thanks for any critique or pointers.
Best,
Bnav
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next reply other threads:[~2026-01-14 0:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-13 2:15 'bnv' via Bitcoin Development Mailing List [this message]
2026-01-18 13:44 ` [bitcoindev] " Giulio Golinelli
2026-01-19 23:55 ` 'bnv' via Bitcoin Development Mailing List
2026-01-20 2:29 ` Giulio Golinelli
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