example-rps-game/LLM.md

FHE Rock Paper Scissors - Project Context

Overview

A decentralized Rock Paper Scissors game using Fully Homomorphic Encryption (FHE) on the Lux blockchain. Players submit encrypted moves that are compared on-chain without revealing choices until the result is determined.

Architecture

Smart Contract: FHERockPaperScissors.sol

• Location: packages/hardhat/contracts/FHERockPaperScissors.sol
• Dependencies: @luxfi/contracts/fhe/FHE.sol
• Core Types:
  • euint8 - Encrypted unsigned 8-bit integers for player choices
  • ebool - Encrypted booleans for comparison results

Game Flow

1. Player 1 creates game with bet amount
2. Player 2 joins with matching bet
3. Both players submit encrypted moves (1=Rock, 2=Paper, 3=Scissors)
4. Contract performs FHE operations to determine winner
5. Winner receives combined bet

Key FHE Operations

// Trivial encryption for constants
ENCRYPTED_ROCK = FHE.asEuint8(1);

// Encrypted comparisons
ebool player1Wins = FHE.eq(FHE.add(player1Choice, ENCRYPTED_ONE), player2Choice);

// Decrypt for final result
FHE.decrypt(winnerChoice);

Development Setup

Local Testing with Mock Contracts

# Start Anvil (local chain)
cd /Users/z/work/luxfhe/mocks/foundry
anvil --code-size-limit 100000

# Deploy mock FHE contracts
npx hardhat deploy-mocks-on-anvil --network anvil

Mock Contracts Deployed

• FHE Network: 0xeA30c4B8b44078Bbf8a6ef5b9f1eC1626C7848D9
• ACL: 0x9fE46736679d2D9a65F0992F2272dE9f3c7fa6e0
• ZkVerifier: 0x0000000000000000000000000000000000000100
• QueryDecrypter: 0x0000000000000000000000000000000000000200

Running the Project

# Compile contracts
yarn compile

# Start UI
yarn start  # Next.js on port 3000

# Run tests
yarn test

SDK Usage

The project uses @luxfhe/sdk for client-side FHE operations:

• Import from @luxfhe/sdk/web for browser
• Main export: { fhe }
• React hook: useFHE() (all caps FHE)

Important Notes

• No test files exist yet - tests need to be written
• Uses scaffold-eth-2 monorepo structure
• FHE operations require mock contracts for local testing
• Real FHE backend requires Docker images (luxfi/fhe) which need to be published

File Structure

rps-game/
├── packages/
│   ├── hardhat/
│   │   ├── contracts/
│   │   │   └── FHERockPaperScissors.sol
│   │   └── test/  # Empty - needs tests
│   └── nextjs/
│       └── app/   # Next.js 15 with App Router
├── package.json   # Workspace root
└── LLM.md        # This file