Chain Layer — EAS Attestation¶

How AuditAI posts audit results to Ethereum Attestation Service on Sepolia.

Overview¶

The chain layer (src/chain/eas_attest.py) handles on-chain attestation via Ethereum Attestation Service (EAS) on Sepolia testnet. It ABI-encodes audit data, builds an EIP-1559 transaction, signs it, and submits it to the EAS contract.

Contract Addresses (Sepolia)¶

Contract	Address
EAS	`0xC2679fBD37d54388Ce493F1DB75320D236e1815e`
Schema Registry	`0x0a7E2Ff54e76B8E6659aedc9103FB21c038050D0`

Schema Structure¶

The attestation schema (pre-registered):

uint8 auditScore, uint16 vulnerabilitiesFound, string auditMode, uint64 timestamp, address contractAddress

ABI-encoded with eth_abi.encode():

def _encode_audit_data(contract_address, audit_score, vulnerabilities_found, audit_mode, timestamp):
    return eth_abi.encode(
        ["uint8", "uint16", "string", "uint64", "address"],
        [audit_score, vulnerabilities_found, audit_mode, timestamp, contract_address],
    )

Score Computation¶

_SEV_TO_SCORE = {
    "critical": 1, "high": 3, "medium": 5,
    "low": 7, "informational": 9, "info": 9,
}

def compute_audit_score(vulnerabilities):
    if not vulnerabilities:
        return 10  # perfect score
    worst = 10
    for v in vulnerabilities:
        sev = v.get("severity", "medium").lower()
        worst = min(worst, _SEV_TO_SCORE.get(sev, 5))
    return worst

Transaction Building¶

The module supports EIP-1559 transactions with automatic fallback to legacy gas pricing:

# EIP-1559 (preferred)
tx_params = {
    "chainId": 11155111,
    "from": account.address,
    "nonce": nonce,
    "gas": 300_000,
    "maxFeePerGas": base_fee * 2 + max_priority,
    "maxPriorityFeePerGas": max_priority,
}

# Fallback: legacy gasPrice
legacy_params = {
    "chainId": 11155111,
    "from": account.address,
    "nonce": nonce,
    "gas": 300_000,
    "gasPrice": w3.eth.gas_price,
}

RPC Connection¶

The module tries multiple Sepolia RPC endpoints with fallback:

fallbacks = [
    rpc_url,                                           # from .env
    "https://sepolia.drpc.org",
    "https://rpc.sepolia.org",
    "https://ethereum-sepolia-rpc.publicnode.com",
]

Each endpoint is tested with a 10-second timeout. If all fail, the attestation degrades to mock mode.

5 Degradation Gates¶

The module has 5 sequential gates. Each gate, if failed, returns a mock hash with a warning:

Gate 1: WALLET_PRIVATE_KEY (ISC-7)¶

private_key = os.getenv("WALLET_PRIVATE_KEY", "").strip()
if not private_key:
    return {"success": False, "tx_hash": _mock_tx_hash("no-key"), "message": "...", "mock": True}

Gate 2: SCHEMA_UID (ISC-11)¶

schema_uid = os.getenv("SCHEMA_UID", "").strip()
if not schema_uid.startswith("0x") or len(schema_uid) != 66:
    return {"success": False, "tx_hash": _mock_tx_hash("bad-schema"), "message": "...", "mock": True}

Gate 3: RPC Connection (ISC-8)¶

try:
    w3 = _get_web3()
except ConnectionError:
    return {"success": False, "tx_hash": _mock_tx_hash("rpc-fail"), "message": "...", "mock": True}

Gate 4a: TX Build (ISC-9)¶

try:
    tx = eas.functions.attest(...).build_transaction(tx_params)
except Exception:
    # try legacy gasPrice
    tx = eas.functions.attest(...).build_transaction(legacy_params)

Gate 4b/c: TX Send/Receipt (ISC-10)¶

signed = w3.eth.account.sign_transaction(tx, private_key=private_key)
tx_hash = w3.eth.send_raw_transaction(signed.raw_transaction)
receipt = w3.eth.wait_for_transaction_receipt(tx_hash, timeout=60)

if receipt.status == 1:
    return {"success": True, "tx_hash": tx_hex, "mock": False}
else:
    return {"success": False, "tx_hash": f"error-revert-{tx_hash.hex()[:16]}", "mock": False}

Mock Hashes¶

Mock hashes are deterministic SHA-256 digests prefixed with mock-:

def _mock_tx_hash(label: str) -> str:
    digest = hashlib.sha256(f"mock-eas-{label}-{time.time()}".encode()).hexdigest()
    return f"mock-0x{digest[:64]}"