What is Fairway?

Fairway is a decentralized compliance infrastructure for making KYC/AML checks programmable across Cardano, Midnight, and EVM, without putting PII on-chain.

We store KYC data in decentralized off-chain storage (the “Vault”), use a Fairway Cloud Agent via API with a Witness to generate a Midnight ZK-proof bound to a specific wallet address, and record that proof on Midnight’s public ledger.

A reference to that Midnight proof (the proof UTXO) is then embedded in Merkle trees on Cardano and/or EVM, alongside Fairway’s signature and the user’s eligibility flags. dApps verify Merkle membership + Fairway signature + epoch freshness, and can later audit the referenced Midnight UTXO.

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Why It Matters

• For Developers → add a single eligibility check (Merkle inclusion + signature verify) to your validator/contract.

• For Institutions → get auditability (via Midnight proof references) without handling raw PII on-chain.

• For Users → prove once, reuse across chains; no document leakage.

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How It Works

Core components

• Vault (decentralized storage) — holds KYC documents/PII off-chain.

• Cloud Agent — verifies inputs, runs Witness logic, and generates ZK-proofs on Midnight bound to the user’s wallet.

• Midnight proof UTXO — immutable record of the ZK result on Midnight’s public ledger.

• Merkle Trees (Cardano & EVM) — compact allowlists of wallet → claims/flags + midnight_ref, signed by Fairway.

• Policy Engine — dApp-side rule evaluation (YES/NO) based on Merkle membership + epoch freshness.

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Merkle Leaf (Cardano/EVM) — canonical fields

{
  "address": "addr1... | 0x...",
  "claims": ["KYC1_OK", "EU_RESIDENT"],
  "midnight_ref": "0x<txid>#<index>",
  "epoch": 391,
  "fairway_sig": "sig(fairway_key, hash(root || epoch || midnight_ref))"
}

Verifier MUST:

1. Verify Merkle membership of address with the on-chain root.

2. Verify Fairway signature over (root, epoch, midnight_ref) using the chain-appropriate key.

3. Enforce epoch freshness (revocation).

4. (Optional, for audits) Resolve midnight_ref on Midnight to validate provenance.

EVM note: you can integrate via (A) Merkle allowlist guard or (B) ERC-3643 adapter that internally checks Fairway eligibility. Both carry the midnight_ref for auditability.

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Key Principles

• No PII on-chain — only commitments, signatures, and references.

• Auditability by reference — every Merkle leaf links to a Midnight proof UTXO.

• Composable — same proof powers Cardano and EVM integrations.

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