POLY_1271 Signing Chain

For deposit wallet (sigtype 3 / POLY_1271) orders to work end-to-end, four conditions must hold:

The Full Chain

POST /auth/api-key          → bind L2 key to deposit wallet
  POLY_ADDRESS = depositWallet
  POLY_SIGNATURE = ERC-7739 wrapped ClobAuth from EOA

POST /order (L2 HMAC)       → CLOB HTTP gate
  POLY_ADDRESS = depositWallet → matches L2 key binding ✓

signedOrderPayload {
  maker  = depositWallet
  signer = depositWallet     ← must equal maker for sigtype 3
  signatureType = 3
  signature = ERC-7739 wrapped (636 hex chars)
}

CTFExchangeV2.isValidSignature(depositWallet, hash, wrappedSig)
  → deposit wallet validates EOA sig via ERC-1271 ✓

Step 1 — L2 Key Binding

The L2 API key must be bound to the deposit wallet address, not the EOA.

headers, err := auth.BuildL1HeadersForDepositWallet(
    privateKeyHex,  // EOA signs
    chainID, timestamp, nonce,
    depositWallet,  // ← key bound to this address
)
// POLY_ADDRESS = depositWallet
// POLY_SIGNATURE = ERC-7739 wrapped ClobAuth

Step 2 — CLOB HTTP Gate

The CLOB checks that POLY_ADDRESS in L2 HMAC headers matches the address the API key was minted for. Since the key is bound to the deposit wallet, the L2 POLY_ADDRESS must be the deposit wallet.

Step 3 — Order Struct

{
  "order": {
    "maker": "0xDepositWallet",
    "signer": "0xDepositWallet",
    "signatureType": 3,
    "signature": "0x...636 chars..."
  }
}

The order signature is an ERC-7739 TypedDataSign wrapper: innerSig(65) || appDomainSep(32) || contents(32) || contentsType(186) || uint16BE(186) = 636 hex chars.

Step 4 — On-Chain Validation

The CTF Exchange V2 calls depositWallet.isValidSignature(hash, wrappedSig). The wallet unwraps the ERC-7739 envelope, verifies the EOA signature, and returns 0x1626ba7e (ERC-1271 magic value).

L1 Auth vs Order Signing

Aspect	L1 (ClobAuth)	Order (POLY_1271)
Signature	ERC-7739 wrapped ClobAuth (406 chars)	ERC-7739 wrapped order (636 chars)
Outer domain	ClobAuthDomain v1	Polymarket CTF Exchange v2
Purpose	Create L2 API key	Authorize trade

See Also

• Deposit Wallets — wallet architecture
• Smart Contracts — factory and exchange addresses
• CLOB API — order placement endpoints