Files
plm-lottery/docs/adr/ADR-07-ogni-decisione-sposta-denaro-base-risposta.md
davideandClaude Sonnet 5.5 db24287ea5 Make the draw a commit-reveal at a fixed, confirmed, quorum-agreed height with a public proof (B-73, RND-14 … RND-20, RND-33 … RND-37, DAT-61 … DAT-66, API-25, API-45, AUD-24 … AUD-27, AUD-37, ELC-15, SEC-56, ADR-24, ADR-25)
The seed was the hash of the first block seen after the close, so a miner holding tickets
could withhold blocks until one made them win, the active Electrum server could pick which
real block was used by not announcing another (a failed corroboration even moved the draw to
the next block), and the participant order was the server-only `broadcast_at` with no
tie-break, so nobody could recompute the result.

- Open: every round gets a 32-byte `server_seed`, stored only Fernet-encrypted with the
  master-xprv key (`server_seed_enc`), with its published `server_seed_hash`;
  `draw_confirmations` is copied from round_config. The plaintext column is written only by
  the reveal.
- Entering `drawing` (one transaction, `draw_committed` audit row): participants ordered by
  bet txid, each `draw_position`, `participants_hash` (sha256 of `txid:vout:address\n`
  lines; new `bet_vout`), `draw_height = tip_at_close + 1`. A tip of 0 keeps the round
  `closing` (`draw_baseline_tip_unknown`, once per round). All persisted, so a resumed draw
  reads rather than recomputes (the `_tick` branch itself is B-81).
- `_complete_draw` / `_wait_for_draw_block` replace `_wait_for_next_block`: wait for
  `draw_confirmations` blocks from `draw_height`, then `ElectrumListener.agreed_block_hash`
  asks every server, the active one included, for the header at that exact height (valid
  work, >= 2 other answers, strict majority of all); no agreement means the same height is
  asked again and `draw_header_corroboration_failed` is written once per distinct reported
  hash. `draw_stalled` now counts from the last tip advance, or from when the quorum started
  to fail. Seed = sha256(server_seed || block_hash || participants_hash), index = seed mod n.
- The winner, the seed and the reveal (`server_seed`, `winner_drawn` payload) are written in
  one transaction; a round closing with no participants reveals too. A round opened before
  this change (no commitment) is given a secret as it enters `drawing`.
- `GET /rounds/{id}/proof` (public, 404 `round_not_found`, translated in all 7 languages) and
  the new fields on `GET /rounds/current`; `draw_confirmations` in `/admin/config` and the
  /admin form; `server_seed_hash`/`draw_height` in `/admin/rounds`, never the secret.
- Alembic d3e8b15a7c42 (plain add_column / create_index, expression indexes untouched).
- Docs: the B-73 `*Stato:*`/`*Oggi:*` lines are gone, guides and CLAUDE.md describe the new
  draw. Ambiguities resolved in api.md: the proof's participants also carry `amount_sats`
  (RND-37 lists it); `seed` is decimal in the proof and hex in the audit row, as specified.

Tests changed because the spec changed: ElectrumListener.corroborate_header (asked only the
other servers about the block the active one announced) is replaced by agreed_block_hash and
its quorum tests ported; draw_winner takes the secret and the list fingerprint; the four
_wait_for_next_block scheduler tests are replaced by _wait_for_draw_block ones (fixed height,
confirmations, same-height retry, stall clock). New: test_draw_proof.py recomputes the winner
independently from the public proof, checks the plaintext secret is nowhere in the database,
the API or the log before the reveal, and that a second pass over a `drawing` round yields
the same winner. Mutation-checked: ordering by broadcast_at, an early reveal and asking the
tip instead of the draw height each fail tests.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
2026-10-14 16:29:09 +02:00

2.6 KiB

ADR-07 — Ogni decisione che sposta denaro in base a una risposta di rete è corroborata da un quorum degli altri server configurati

  • Stato: Accettata
  • Area: Conferme e fiducia nella rete
  • Fonte di verità per: la scelta di progetto descritta qui sotto; i requisiti (PREFISSO-NN) che la attuano stanno nei documenti di dominio, indicati nelle Conseguenze.

Decisione

Ogni decisione che sposta denaro in base a una risposta di rete è corroborata da un quorum degli altri server configurati: il blocco che semina l'estrazione, una moneta data per spesa all'esterno, un nuovo deposito da accreditare, il ripristino di una moneta, la conferma di una transazione (con prova merkle contro un header che possediamo), l'abbandono di una transazione, le monete del round verificate prima del pagamento. Si interrogano solo gli altri server, mai quello attivo (che è ciò che un attaccante controllerebbe); servono almeno 2 risposte e la maggioranza stretta di chi risponde. Il server rifiuta di partire con meno di 2 server di riserva, salvo ALLOW_NO_QUORUM=true (solo sviluppo). Se rispondono meno di 2 server, la corroborazione fallisce.

  • Motivazione: un solo server ostile non deve poter scegliere il vincitore (B-28), azzerare un saldo (B-29) o gonfiarlo (B-59), né far credere confermato un pagamento mai trasmesso (B-83). I saldi si muovono in entrambe le direzioni, quindi entrambe richiedono il quorum. Con 0 o 1 server di riserva la «maggioranza» è una sola voce, o nessuna (B-84).
  • Alternative scartate: quorum facoltativo, che passa sempre con la lista vuota (la regola precedente: il default di .env.example spegneva ogni difesa senza avvisare).
  • Conseguenze: una corroborazione fallita ritarda, non perde e non libera fondi (ADR-51): il deposito è riproposto al refresh successivo, l'estrazione richiede di nuovo lo stesso blocco. Il quorum resta fra server scelti dall'operatore ([LIM-11]). Regole in connessione-electrum.md (B-83, B-84).

Codice: app/electrum/listener.py:ElectrumListener._corroborate_majority · app/electrum/listener.py:ElectrumListener.agreed_block_hash · app/electrum/listener.py:ElectrumListener.corroborate_utxo_spent · app/electrum/listener.py:ElectrumListener.corroborate_utxo_credit · app/electrum/listener.py:ElectrumListener.corroborate_utxo_reinstatement · app/electrum/listener.py:ElectrumListener.confirmation_proven · app/main.py:lifespan · Test: tests/unit/test_electrum_listener.py, tests/unit/test_confirmation_proof.py