TrunkGuard: FHE-Powered Uniswap v4 Hook

Private, MEV-resistant swaps on Uniswap v4 using Fhenix Fully Homomorphic Encryption (FHE).

This repo contains a Uniswap v4 hook that validates encrypted orders and records encrypted outputs, plus a simple FHE-enabled ERC20 used in tests and scripts.

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What’s integrated

• Uniswap v4 hooks via BaseHook in src/TrunkGuardSwapHook.sol
• Fhenix CoFHE contracts via @fhenixprotocol/cofhe-contracts/FHE.sol
• Foundry-based tests with CoFHE mocks via cofhe-foundry-mocks

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Where Fhenix is used (and how)

Files:

• src/TrunkGuardSwapHook.sol

  • Imports: import {FHE, euint128, ebool, Common} from "@fhenixprotocol/cofhe-contracts/FHE.sol";
  • Stores encrypted inputs/outputs per pool and order:
    • mapping(PoolId => mapping(bytes32 => euint128)) public encryptedOrders;
    • mapping(PoolId => mapping(bytes32 => euint128)) public encryptedMinOutputs;
    • mapping(PoolId => mapping(bytes32 => euint128)) public encryptedOutputs;
    • mapping(PoolId => mapping(bytes32 => ebool)) public swapValidations;
  • Accepts encrypted inputs via:
    • submitEncryptedSwap(PoolKey key, euint128 encAmount, euint128 encMinOutput, bytes data)
  • Validates homomorphically inside _beforeSwap:
    • Computes expected output with FHE.mul(encAmount, encPrice)
    • Compares via FHE.gte(expectedOutput, encMinOutput) to produce an ebool
  • Records BalanceDelta in _afterSwap (as encrypted output)
  • Off-chain decryption flow helpers:
    • validateSwap, requestOutputDecryption, revealOutput

• src/HybridFHERC20.sol

  • Example token used in tests/scripts; standard ERC20-like interface with helper mints

Key concepts:

• euint128, ebool are encrypted integer/boolean types
• Use Common.isInitialized(x) to check if encrypted values are set
• Use FHE.asEuint128(value) to create encrypted constants on-chain

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Where Uniswap v4 is used (and how)

Files:

• src/TrunkGuardSwapHook.sol

  • Inherits BaseHook and implements:
    • _beforeSwap(…) internal override returns (bytes4, BeforeSwapDelta, uint24)
    • _afterSwap(…) internal override returns (bytes4, int128)
  • Reads pool state via IPoolManager and StateLibrary (e.g. getSlot0(key.toId()))

• Tests and setup use v4-core helpers via test/utils and Foundry fixtures.

Hook address permissions:

• Uniswap v4 encodes permissions in the least-significant 14 bits of the hook’s address (see @uniswap/v4-core/src/libraries/Hooks.sol).
• For this hook we require at minimum:
  • Hooks.BEFORE_SWAP_FLAG
  • Hooks.AFTER_SWAP_FLAG
  • optionally Hooks.BEFORE_SWAP_RETURNS_DELTA_FLAG if returning deltas

Deploying to a valid address (tests):

• Use HookMiner.find from v4-periphery to generate a CREATE2 salt that yields an address with the proper flags.
• Example (see comments in test/TrunkGuardSwapHook.t.sol):
  • (address hookAddress, bytes32 salt) = HookMiner.find(deployer, flags, type(TrunkGuardSwapHook).creationCode, abi.encode(manager));
  • new TrunkGuardSwapHook{salt: salt}(manager) and assert address(hook) == hookAddress

Troubleshooting SenderNotAllowed / HookAddressNotValid:

• These revert when the hook address does not encode the required flags
• Always deploy the hook to an address returned by HookMiner.find
• Ensure you pass the same constructor args to both find and new … {salt: …}

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Project layout

trunkGuard/
├─ src/
│  ├─ TrunkGuardSwapHook.sol        # Main FHE-enabled Uniswap v4 hook
│  ├─ HybridFHERC20.sol             # Simple token used for local tests/scripts
│  └─ interface/
│     └─ IFHERC20.sol
├─ test/
│  ├─ TrunkGuardSwapHook.t.sol      # Core tests (Foundry + CoFHE mocks)
│  └─ utils/…                       # Uniswap v4 testing utilities
├─ script/
│  ├─ 01_CreatePoolAndMintLiquidity.s.sol
│  ├─ 01a_CreatePoolOnly.s.sol
│  ├─ 02_AddLiquidity.s.sol
│  ├─ 03_Swap.s.sol                 # Simple swap script
│  └─ Anvil.s.sol                   # Local end-to-end demo
├─ foundry.toml
├─ hardhat.config.ts
└─ remappings.txt

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Quickstart (local)

Prereqs:

• Foundry (forge, anvil)
• Node.js (for installing packages if needed)

Install and build:

pnpm install || npm install
forge build

Run tests:

forge test -vv

Run local demo on Anvil:

anvil --gas-limit 30000000 &
forge script script/Anvil.s.sol \
  --rpc-url http://localhost:8545 \
  --broadcast

Swap-only demo:

forge script script/03_Swap.s.sol \
  --rpc-url http://localhost:8545 \
  --broadcast

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Notes on tests

• Tests inherit CoFheTest from cofhe-foundry-mocks to simulate FHE flows
• You may mock decryption results via the mock task manager helpers if needed
• If you see SenderNotAllowed or HookAddressNotValid during pool init:
  • Switch to HookMiner.find deployment flow in setUp() and re-run

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Extending this repo

• Add richer validation logic in _beforeSwap
• Extend revealOutput to emit decrypted outputs after authorized reveal
• Expand scripts to demonstrate multi-pool scenarios

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License

MIT. See LICENSE.