FHEVM Foundry Template

A Foundry-based template for developing Fully Homomorphic Encryption (FHE) enabled Solidity smart contracts using the FHEVM protocol by Zama.

Quick Start

Prerequisites

• Foundry: Installation guide

Installation

1. Install dependencies

   forge soldeer install

2. Compile and test

   forge build
   forge test -vvv

3. Deploy to local network

   Start an Anvil node with the FHEVM host contracts deployed (requires forge-fhevm):

   # From the forge-fhevm directory
   ./deploy-local.sh

   Then deploy to the local network:

   forge script script/DeployFHECounter.s.sol --rpc-url http://localhost:8545 --broadcast

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Warning

🚧 Tests and scripts run only against the local FHEVM mock — never against Sepolia or any live FHEVM deployment.

forge test (and any script that depends on FHE decryption) relies on forge-fhevm's in-memory mock of the FHEVM host contracts — mock KMS / input signers, plaintext database. Those mocks do not exist on a live network, so pointing tests or test-style scripts at Sepolia will fail:

# ❌ FAIL — no mock host contracts on Sepolia
forge test --rpc-url http://sepolia --broadcast

# ❌ FAIL — encrypted state on a live network can't be decrypted in-process
forge script script/SomeFHEScript.s.sol --rpc-url http://sepolia --broadcast

To interact with a contract on Sepolia, deploy it (step 4 below) and interact through the Zama SDK from your dApp.

4. Deploy to Sepolia Testnet

   cp .env.example .env
   # Edit .env with your deployer key and RPC URL
   
   source .env
   forge script script/DeployFHECounter.s.sol \
       --rpc-url $RPC_URL \
       --private-key $DEPLOYER_PRIVATE_KEY \
       --broadcast --verify

Project Structure

fhevm-foundry-template/
├── src/                 # Smart contract source files
│   └── FHECounter.sol   # Example FHE counter contract
├── test/                # Test files
│   └── FHECounter.t.sol # Tests using forge-fhevm
├── script/              # Deployment scripts
│   └── DeployFHECounter.s.sol
├── foundry.toml         # Foundry configuration
└── remappings.txt       # Dependency remappings

Available Scripts

Script	Description
forge build	Compile all contracts
forge test -vvv	Run all tests
forge test --match-test test_name -vvv	Run a single test
forge fmt	Format code
forge fmt --check	Check formatting

Documentation

• FHEVM Documentation
• FHEVM Quick Start Tutorial
• forge-fhevm Documentation

License

This project is licensed under the BSD-3-Clause-Clear License. See the LICENSE file for details.

Support

• GitHub Issues: Report bugs or request features
• Documentation: FHEVM Docs
• Community: Zama Discord