Nethereum.AppChain.Contracts

NuGet: Nethereum.AppChain.Contracts | Source: src/Nethereum.AppChain.Contracts/

Nethereum.AppChain.Contracts

Solidity smart contracts for the Nethereum AppChain anchoring and messaging system. Built with Foundry.

Contracts

Core

Contract	Purpose
AppChainAnchor.sol	Anchor registry — stores block anchors per AppChain with pluggable proof verification. AggregatedAnchor struct with 3 proof systems (NoProof, StarkHashOffChain, SnarkOnChain) and extensible registry.
AppChainHub.sol	Public AppChain registry and messaging hub. Chain ID reservation (prevents squatting via registration fee), cross-chain messaging with authorized senders, anchor storage, message acknowledgment with Merkle root checkpoints. Optional — AppChains deploy their own AppChainAnchor independently; the Hub provides discovery, coordination, and a standardised messaging layer.
AppChainPolicy.sol	Membership and policy governance — Merkle-root membership management (writers/admins/blacklist), configurable policy parameters (calldata limits, log limits, gas limits, sequencer), and epoch-based tree rebuilding.
AppChainProofManager.sol	Proof registry — records per-block proof submissions from authorized provers (direct or bond-requested), each checked against the anchor's minimum proof system.

Authority & Access Control

Contract	Purpose
SimpleAuthority.sol	Authority contract with operator + per-chain authorized provers. Implements IAuthority. Supports operator validation, prover authorization/revocation, and ownership transfer.
IAuthority.sol	Interface for pluggable authority contracts.

Verification

Contract	Purpose
IVerifier.sol	Standard verifier interface: verify(bytes proof, uint256[] publicInputs) → bool. All verifiers implement this.
CalldataFormatVerifier.sol	Validates compressed block header calldata format (version byte + Brotli/Zlib envelope).
StarkBlobCommitmentVerifier.sol	Validates STARK proof hash with EIP-4844 blob commitment reference.
CalldataStarkVerifier.sol	Combined calldata + STARK hash verification.
PipelinePayloadVerifier.sol	Validates multi-section encoded pipeline payloads (headers + proofs + DA reference).
MockProofVerifier.sol	Test verifier that validates proof format without cryptography — returns false on malformed input (requires a 256-byte proof, at least 6 public inputs, non-zero commitment, non-zero chain identity, and correct batch block ordering). Does not verify the elliptic-curve pairing.
ZiskVerifierAdapter.sol	Adapter wrapping the ZisK zkVM SNARK verifier (IZiskVerifier) to the IVerifier interface. It accepts a proof only when the first eight Zisk public values (32-bit words, each held in a 64-bit public) hold keccak256(abi.encodePacked(publicInputs)); a proof of the guest's generic outputs does not carry that commitment and is rejected by the adapter (it still verifies through ZiskVerifier.verifySnarkProof).
IZiskVerifier.sol	ZisK-specific SNARK verifier interface (verifySnarkProof(bytes32 programVK, bytes32 rootCVadcopFinal, bytes publicValues, bytes proofBytes)), the zkVM's native verifier bridged to IVerifier by ZiskVerifierAdapter.
ZiskVerifier.sol	Zisk 1.3.1-alpha PLONK verifier (copied from Zisk's zisk-contracts): implements IZiskVerifier over PlonkVerifier. getRootCVadcopFinal() returns the root a leaf proof is wrapped under; verifySnarkProof reverts with InvalidProof on a bad proof. The generated C# service is Nethereum.AppChain.Anchoring.ZiskVerifier.ZiskVerifierService.
PlonkVerifier.sol	The snarkJS-generated PLONK verifier for the Zisk final circuit that ZiskVerifier inherits.

Proof System Registry

The AppChainAnchor contract maps proof system IDs to verifier contracts via registerProofSystem(uint8 id, address verifier, bool requiresProof):

ID	Enum Name	Verifier	requiresProof	Verification
0	NoProof	address(0)	false	Trust operator
1	StarkHashOffChain	optional	false	Off-chain STARK verification
2	SnarkOnChain	required	true	Full on-chain SNARK verification via IVerifier.verify() (pluggable verifier; shipped: ZiskVerifierAdapter)

The registry is extensible — additional proof systems can be registered by the registry owner (registerProofSystem is onlyOwner). 7 C# submission strategies (DA × Proof mode combinations) map to these 3 on-chain proof system IDs.

See STRATEGY_VERIFIERS.md for the full strategy-to-verifier mapping.

Build

forge build

Test

forge test -vvv

C# Code Generation

Generated Nethereum contract services live in:

• src/Nethereum.AppChain.Anchoring/AppChainAnchor/ — AnchorService, definitions, extensions
• src/Nethereum.AppChain.Anchoring/SimpleAuthority/
• src/Nethereum.AppChain.Anchoring/AppChainProofManager/
• src/Nethereum.AppChain.Anchoring/MockProofVerifier/
• src/Nethereum.AppChain.Anchoring/ZiskVerifierAdapter/
• src/Nethereum.AppChain.Anchoring/Hub/Contracts/AppChainHub/
• src/Nethereum.AppChain.Policy/Contracts/AppChainPolicy/

Regenerate with:

Nethereum.Generator.Console generate from-config -cfg .nethereum-gen.multisettings

Security Model

PREVIEW — Contracts are audited internally. External audit recommended before mainnet deployment.

AppChainAnchor:

• Authority-gated anchor submission — each chain registers its own IAuthority contract (e.g. SimpleAuthority)
• Proof system registry with requiresProof validation — verifier address required when proof is mandatory
• One-way raiseMinimumProofSystem prevents downgrade attacks
• MockProofVerifier provided for testing only — must not be registered on production chains

AppChainHub:

• ReentrancyGuard on all ETH-transferring functions (registration, messaging, withdrawals)
• EIP-2 compliant ECDSA signature verification (s-value check prevents malleability)
• Pull-payment pattern using call{value} for all withdrawals and refunds
• CEI (Checks-Effects-Interactions) ordering enforced — state updates before external calls
• Per-chain authorized sender allowlist for message submission
• Pluggable IProofVerifier per chain for anchor proof verification

AppChainPolicy:

• Merkle-root based membership (writers, admins, blacklist)
• Blacklist verification via proof in invite() — prevents re-adding banned addresses
• Epoch-based tree rebuilding for membership rotation
• Admin-gated policy parameter changes