Contracts

All contracts are MIT-licensed Solidity 0.8.28, built with Foundry.

cd blockchain/contracts
forge build
forge test          # 162 tests
forge test -vvv     # with traces
forge fmt

Layout

blockchain/contracts/src/
├── L2/                          deployed on the underlying L2
│   ├── KauraxPortal.sol         deposits, withdrawal prove/finalize, pause
│   ├── KauraxL2OutputOracle.sol KAURAX state commitments
│   ├── KauraxBatchInbox.sol     KAURAX transaction data anchor
│   └── KauraxL2ERC20Bridge.sol  ERC-20 escrow
├── L3/                          deployed on KAURAX (predeploys)
│   ├── L3ToL2MessagePasser.sol  withdrawal origination + Merkle tree
│   ├── KauraxL3ERC20Bridge.sol  mint/burn counterpart
│   └── KauraxBridgedERC20.sol   bridged token representation
├── libraries/
│   ├── Hashing.sol              output root and withdrawal hashing
│   ├── MerkleTree.sol           append-only tree + proof verification
│   ├── AddressAliasHelper.sol   cross-domain sender aliasing
│   └── Types.sol
├── interfaces/
└── examples/                    HelloKaurax, Counter, SimpleStorage, KauraxToken

Predeploy addresses

Address	Contract
`0x4200000000000000000000000000000000000016`	`L3ToL2MessagePasser`
`0x4200000000000000000000000000000000000010`	`KauraxL3ERC20Bridge`

Installed at genesis by infra/scripts/devnet/genesis.ts, which places the compiled runtime bytecode at those addresses — the same state a production op-geth would load from genesis.json.

Consensus-critical hashing

outputRoot     = keccak256(abi.encode(version, stateRoot, withdrawalTreeRoot, latestBlockHash))
withdrawalHash = keccak256(abi.encode(nonce, sender, target, value, gasLimit, keccak256(data)))

Mirrored in blockchain/l3/src/settlement/hashing.ts. These two implementations must agree. A divergence would either block every withdrawal or admit one that was never made.

Test coverage

Suite	Tests	Covers
`MerkleTree.t.sol`	8	Incremental root equals full rebuild (fuzzed), proof round-trip, forged leaf, wrong index, malformed proof
`KauraxL2OutputOracle.t.sol`	13	Schedule, access control, future-block bound, L2 reorg pin, challenger deletes, finalized-delete ban, binary search
`KauraxPortal.t.sol`	23	Deposits, aliasing, pause, full withdrawal lifecycle, forged withdrawals, leaf substitution, re-prove semantics, double finalization, reentrancy, `l3Sender`
`KauraxBatchInbox.t.sol`	10	Contiguity, gaps, overlaps, access control, key rotation
`Bridge.t.sol`	6	ERC-20 round trip, alias enforcement, escrow drain attempts, token mismatch
`KauraxNames.t.sol`	29	Label validation, pricing, expiry, grace period, primary-name spoofing
`KauraxSwap.t.sol`	30	Pools, liquidity, swaps, native KAX, k-invariant fuzz, underpayment
`KauraxLaunchpad.t.sol`	27	Escrow, caps, refunds, claim/refund exclusivity, no stranded KAX

The security-relevant tests assert what must fail, not only what must succeed: a forged withdrawal, a substituted leaf index, a tampered output-root preimage, a direct escrow drain, and an unaliased deposit finalization all revert with specific errors.

Deployment

# Settlement contracts, on the L2
forge script script/DeploySettlement.s.sol:DeploySettlement \
  --rpc-url $L2_RPC_URL --broadcast

# Example contracts, on KAURAX
forge script script/DeployExamples.s.sol:DeployExamples \
  --rpc-url $KAURAX_RPC_URL --broadcast

Every parameter comes from the environment. Nothing is hardcoded, and no key is committed.

Audit status

None. No contract here has been audited. Do not deposit anything of value.