1 / The problem

Bids on an open marketplace are a public book

Read off the live listing page, 2026-09-29 — every amount and every rival's move is visible

2 / The round

Three sealed bids arrived — only the seller can read them

0.012, 0.009 and 0.004 ZEC — one sent by hand from a Noir wallet

3 / Reveal

4 / The money trail

5 / Honest limits

No live high bidThe amounts are encrypted, so nobody — not even the seller — can honestly compute a running highest bid. Bidders decide on their own valuation, not on a leaderboard.
Trusted sellerThe seller decides the clearing price and the ranking, and a third party cannot verify those from the chain alone. What the chain does prove is the money.
No withdrawalsA bid cannot be retracted — the transfer is already on-chain. Funds are returned after the reveal, so a bidder must be sure before sending.

6 / Money in motion

Every leg is a real transaction: amounts private, transaction ids public

7 / Wrap

docs/SPEC.md — protocol, SHIELDBID/1
docs/BIDDER_GUIDE.md — how to bid
docs/ENGINE_SETUP.md — run the engine
web/index.html — the live lot page
tools/ — the round's scripts, as run

docs/demo_01_settlement.json — receipt
docs/demo_01_money_trail.json — 12 legs
docs/demo_01_refund_receipts.json — refunds
docs/DEMO_01_REPORT.md — round write-up
docs/SPEC.md §7 — limits, stated plainly

clone the repository and open web/index.html
look up any txid on a Zcash explorer
diff the receipt against SPEC.md
re-run the engine: ENGINE_SETUP.md
check the refund legs address by address

Ran on Zcash mainnet · 12 transactions · about 0.001 ZEC of chain fees