㊙️Noir Stealth Auctions

Solution — Noir Stealth Auction

Goal – Enable any institution to sell (or buy) a $500 k–$10 M block of SPL tokens on Solana in a single click with zero intent‑leak and uniform‑price clearing.

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1. UX at a Glance

Step	Actor	What Happens (User‑Visible)
1. Create Stealth Auction	Seller	Pick asset + cap, sign a delegate‑pull PST. UI shows “Auction created – bids open for X min.”
2. Submit Encrypted Bids	Bidders	Discover auction → enter max price & qty → wallet signs → dApp submits threshold‑encrypted ciphertext.
3. Close & Decrypt	Anyone	At commit deadline, anyone calls triggerDecryption(); keyper nodes publish shares; dApp shows clearing price.
4. Settle Atomically	Program	Seller’s pre‑signed PST is posted → clearAuction() moves tokens ↔ USDC in one instruction; winners / seller receive receipts.

Total user clicks: Seller (2) • Bidder (2).

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2. How It Works Under the Hood

Key Components

1. Threshold Encryption (t‑of‑n) – Bids stay private until the block they clear.

2. Delegate‑Pull PST – Lot remains off‑chain; only a SHA‑256 hash is stored until settlement.

3. Uniform Clearing Price (UCP) – All winning bidders pay the same price, maximising fairness and depth.

4. Atomic Swap Instruction – One Solana program call transfers tokens → winners and USDC → seller—no partial fills, no counter‑party risk.

Minimal On‑Chain State

AuctionState {
  pstHash: bytes32  // seller lot commitment
  mpk: bytes        // encryption master pubkey
  t, n: u8          // threshold params
  commitDL: u64     // Unix ts
  revealDL: u64     // Unix ts
  status: enum {Commit, Reveal, Closed}
}
Ciphertexts[]       // appended during Commit phase
Shares[t]           // stored during Reveal phase

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3. Core Instruction Set

Ix	When	Purpose
createAuction(H, mpk, t, n, DLs)	Start	Store params, open Commit phase.
submitCipher(id, ct)	Commit	Append encrypted bid.
triggerDecryption(id)	Reveal	Emit event for keypers to post shares.
publishShare(id, share, proof)	Reveal	Verify proof, store share.
clearAuction(id, pstBytes)	Close	Reconstruct bids, compute UCP, pull lot via PST, atomically settle.

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4. Privacy ↔ Auditability Matrix

Who Knows What	Before Auction	Before Settlement	After Settlement
Seller lot size	Hidden (hash only)	Hidden	Revealed (lot pulled)
Bid prices / qty	Encrypted	Encrypted	Winners & fills revealed; losers stay private
Clearing price	Unknown	Calculated	Public

Outcome – Both sides remain invisible until the exact block that finalises the trade, yet auditors can verify the uniform‑price clearing on‑chain.

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Next: see Protocol Architecture for gas benchmarks and keyper network design.