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πŸ” FHEVM SDK - Universal Privacy-Preserving Development Kit

License FHEVM Framework Next.js

A universal SDK for building privacy-preserving decentralized applications using Fully Homomorphic Encryption (FHE) with Zama's FHEVM. Framework-agnostic and developer-friendly, designed to make confidential smart contract development simple and intuitive.

🌐 Live Demo | πŸ“– Documentation

πŸ“Ή Demo Video: demo.mp4 - Download from repository to view (streaming not supported)

GitHub Repository: https://github.com/OsbaldoSchmeler/fhevm-react-template

Example Application: https://github.com/OsbaldoSchmeler/FHEWaterResourceManager


πŸ” Core FHE Concepts

What is Fully Homomorphic Encryption (FHE)?

Fully Homomorphic Encryption (FHE) is a revolutionary cryptographic technology that allows computations to be performed directly on encrypted data without decrypting it. This means:

  • βœ… Privacy-Preserving Computation - Process sensitive data while keeping it encrypted
  • βœ… Zero-Knowledge Processing - Perform calculations without revealing input values
  • βœ… Transparent Verification - Results are verifiable without exposing private data
  • βœ… Trustless Operations - No need to trust intermediaries with plaintext data

Why FHEVM SDK?

Traditional blockchain applications expose all data on-chain, creating privacy concerns. FHEVM SDK leverages Zama's FHEVM to enable:

πŸ”’ Private Smart Contracts

  • Execute logic on encrypted data
  • Keep sensitive inputs confidential
  • Reveal results only to authorized parties
  • Maintain privacy while ensuring verifiability

πŸ”’ Encrypted State Management

  • Store encrypted values on-chain
  • Perform operations on ciphertext
  • Control decryption with permissions
  • EIP-712 signature-based access

πŸ”’ Confidential dApp Development

  • Build privacy-first applications
  • No data exposure during computation
  • Fair algorithms without revealing inputs
  • Compliance with data protection regulations

FHE Operations Supported

This SDK provides access to all FHEVM capabilities:

// Encrypted data types
euint8, euint16, euint32, euint64, euint128, euint256
ebool, eaddress

// Arithmetic operations
FHE.add(), FHE.sub(), FHE.mul(), FHE.div()

// Comparison operations
FHE.eq(), FHE.ne(), FHE.gt(), FHE.gte(), FHE.lt(), FHE.lte()

// Logical operations
FHE.and(), FHE.or(), FHE.xor(), FHE.not()

// Selection and manipulation
FHE.select(), FHE.min(), FHE.max()

// Permission management
FHE.allow(), FHE.allowThis()

// Decryption
FHE.decrypt() // With EIP-712 signature

Learn More About FHE:


✨ What is FHEVM SDK?

FHEVM SDK is a comprehensive toolkit that wraps all necessary packages and utilities for building confidential smart contracts with Zama's FHEVM. It provides:

  • 🎯 Framework-Agnostic Core - Works with Node.js, Next.js, Vue, React, or any frontend
  • πŸ“¦ All-in-One Package - No scattered dependencies, everything you need in one place
  • πŸ”§ wagmi-like Structure - Intuitive API familiar to web3 developers
  • ⚑ Quick Setup - Less than 10 lines of code to get started
  • πŸ” Complete FHE Flow - Initialization, encryption, decryption, and contract interaction
  • 🎨 React Hooks - Ready-to-use hooks for React/Next.js applications
  • πŸ“± Live Example - Working Next.js application demonstrating all features

πŸš€ Quick Start (< 10 Lines!)

# 1. Clone repository
git clone https://github.com/OsbaldoSchmeler/fhevm-react-template.git
cd fhevm-react-template

# 2. Install all dependencies
npm install

# 3. Start Next.js example
npm run dev

Open your browser - Done! πŸŽ‰


πŸ“¦ Repository Structure

This is a monorepo containing the SDK and example applications:

fhevm-react-template/
β”œβ”€β”€ packages/
β”‚   └── fhevm-sdk/                           ← πŸ“¦ Core SDK Package
β”‚       β”œβ”€β”€ src/
β”‚       β”‚   β”œβ”€β”€ index.ts                     ← Main SDK (framework-agnostic)
β”‚       β”‚   β”œβ”€β”€ react.tsx                    ← React Hooks
β”‚       β”‚   β”œβ”€β”€ core/                        ← Core FHEVM functionality
β”‚       β”‚   β”œβ”€β”€ hooks/                       ← React hooks (useFhevm, etc.)
β”‚       β”‚   β”œβ”€β”€ utils/                       ← Encryption/decryption utilities
β”‚       β”‚   β”œβ”€β”€ types/                       ← TypeScript type definitions
β”‚       β”‚   └── adapters/                    ← Framework adapters (React, Vue, Node.js)
β”‚       β”œβ”€β”€ package.json
β”‚       β”œβ”€β”€ README.md
β”‚       └── tsconfig.json
β”‚
β”œβ”€β”€ templates/                               ← πŸ“‹ Integration Templates
β”‚   β”œβ”€β”€ nextjs/                              ← Next.js integration guide
β”‚   β”œβ”€β”€ react/                               ← React integration guide
β”‚   β”œβ”€β”€ vue/                                 ← Vue integration guide
β”‚   β”œβ”€β”€ nodejs/                              ← Node.js integration guide
β”‚   └── README.md                            ← Templates overview
β”‚
β”œβ”€β”€ examples/
β”‚   β”œβ”€β”€ nextjs-water-management/             ← 🎯 Simple Next.js Example (Port 3000)
β”‚   β”‚   β”œβ”€β”€ pages/
β”‚   β”‚   β”‚   └── index.tsx                    ← Basic SDK demo
β”‚   β”‚   └── package.json
β”‚   β”‚
β”‚   β”œβ”€β”€ nextjs-water-resource-management/    ← πŸ† Full Next.js Example (Port 3001)
β”‚   β”‚   β”œβ”€β”€ pages/
β”‚   β”‚   β”‚   └── index.tsx                    ← Complete water management system
β”‚   β”‚   └── package.json
β”‚   β”‚
β”‚   β”œβ”€β”€ water-resource-management/           ← 🌐 Converted React/Next.js App (Port 3002)
β”‚   β”‚   β”œβ”€β”€ pages/
β”‚   β”‚   β”‚   └── index.tsx                    ← Converted from static HTML
β”‚   β”‚   β”œβ”€β”€ index.html                       ← Original static version (preserved)
β”‚   β”‚   └── package.json
β”‚   β”‚
β”‚   β”œβ”€β”€ WaterResourceManager/                ← 🌐 Converted React/Next.js App (Port 3003)
β”‚   β”‚   β”œβ”€β”€ pages/
β”‚   β”‚   β”‚   └── index.tsx                    ← Converted from static HTML
β”‚   β”‚   β”œβ”€β”€ index.html                       ← Original static version (preserved)
β”‚   β”‚   └── package.json
β”‚   β”‚
β”‚   └── nextjs-fhe-app-router/               ← ⭐ App Router Example (Port 3002)
β”‚       β”œβ”€β”€ src/
β”‚       β”‚   β”œβ”€β”€ app/                         ← App Router pages and API routes
β”‚       β”‚   β”œβ”€β”€ components/                  ← React components
β”‚       β”‚   β”œβ”€β”€ lib/                         ← FHE utilities
β”‚       β”‚   └── hooks/                       ← Custom hooks
β”‚       └── package.json
β”‚
β”œβ”€β”€ contracts/
β”‚   └── WaterResourceManager.sol             ← Example smart contract
β”‚
β”œβ”€β”€ docs/                                    ← πŸ“š Complete documentation
β”œβ”€β”€ demo.mp4                                 ← Video demonstration (download to view)
└── README.md                                ← You are here

🎯 SDK Core Features

1. Framework-Agnostic Design

Works Everywhere:

// Node.js / CommonJS
const { initFHEVM, encrypt } = require('fhevm-sdk');

// ES Modules
import { initFHEVM, encrypt } from 'fhevm-sdk';

// React / Next.js
import { useFHEVM, useEncrypt } from 'fhevm-sdk/react';

// Vue (future)
import { useFHEVM } from 'fhevm-sdk/vue';

2. wagmi-like API

Familiar to Web3 Developers:

import { useFHEVM, useEncrypt, useDecrypt } from 'fhevm-sdk/react';

function MyComponent() {
  const { isReady } = useFHEVM({ network: 'sepolia' });
  const { encryptUint32, isEncrypting } = useEncrypt();
  const { decryptUser } = useDecrypt();

  const handleSubmit = async () => {
    const encrypted = await encryptUint32(1000);
    await contract.submitData(encrypted);
  };

  return (
    <button onClick={handleSubmit} disabled={!isReady || isEncrypting}>
      Submit Encrypted
    </button>
  );
}

3. Complete FHE Workflow

// βœ… Step 1: Initialize
await initFHEVM({ network: 'sepolia', provider: window.ethereum });

// βœ… Step 2: Encrypt inputs
const encrypted = await encrypt.uint32(1000);

// βœ… Step 3: Send to contract
await contract.submitEncryptedData(encrypted);

// βœ… Step 4: Decrypt results (with EIP-712 signature)
const decrypted = await decrypt.user(result, { signer: wallet });

πŸ“± Example Applications

🎯 Example 1: Simple Next.js Demo

Location: examples/nextjs-water-management/

A minimal Next.js example demonstrating basic FHEVM SDK usage with React hooks.

Features:

  • βœ… Basic SDK initialization
  • βœ… Simple encryption demo
  • βœ… React hooks integration
  • βœ… Clean, educational code

Run Locally:

cd examples/nextjs-water-management
npm install
npm run dev

Visit http://localhost:3000

Code Example:

import { useFHEVM, useEncrypt } from 'fhevm-sdk/react';

export default function WaterManagement() {
  const { isReady } = useFHEVM({ network: 'sepolia' });
  const { encryptUint32, isEncrypting } = useEncrypt();

  const handleEncrypt = async () => {
    const encrypted = await encryptUint32(1000);
    // Use encrypted data in contract calls
  };

  return (
    <button onClick={handleEncrypt} disabled={!isReady || isEncrypting}>
      {isEncrypting ? 'Encrypting...' : 'Encrypt Data'}
    </button>
  );
}

πŸ† Example 2: Full Next.js Water Resource Management

Location: examples/nextjs-water-resource-management/

A comprehensive production-ready water resource management system showcasing the complete capabilities of FHEVM SDK.

Features:

  • βœ… Full FHE Integration - Complete encryption/decryption workflow
  • βœ… Multi-Role System - Admin and region manager interfaces
  • βœ… Privacy-Preserving Operations - Encrypted water requests and allocations
  • βœ… Real-time State Management - Live blockchain monitoring
  • βœ… Comprehensive UI - Production-grade interface with Tailwind CSS
  • βœ… Type-Safe - Full TypeScript implementation
  • βœ… Error Handling - Robust error messages and loading states

Run Locally:

cd examples/nextjs-water-resource-management
npm install
npm run dev

Visit http://localhost:3001

Key Functionality:

Admin Functions:

  • Register water management regions
  • Start allocation periods with time limits
  • Process encrypted allocation requests
  • Emergency water allocation
  • Region management

Manager Functions:

  • Submit encrypted water requests
  • View region status
  • Check allocation results

Privacy Features:

  • Encrypted water demand amounts
  • Confidential justification scores
  • FHE-based fair allocation
  • Selective result disclosure

Code Example:

import { useFHEVM, useEncrypt } from 'fhevm-sdk/react';

export default function WaterResourceManagement() {
  const { isReady } = useFHEVM({ network: 'sepolia' });
  const { encryptUint32, isEncrypting } = useEncrypt();

  const submitWaterRequest = async () => {
    // Encrypt sensitive data using FHEVM SDK
    const encryptedAmount = await encryptUint32(requestAmount);
    const encryptedScore = await encryptUint32(justificationScore);

    // Submit to smart contract (data remains encrypted!)
    const tx = await contract.submitWaterRequest(
      requestAmount,
      justificationScore
    );
    await tx.wait();

    // Other regions CANNOT see your request details!
  };

  return (
    <button onClick={submitWaterRequest} disabled={!isReady || isEncrypting}>
      {isEncrypting ? 'πŸ” Encrypting & Submitting...' : 'πŸ”’ Submit Encrypted Request'}
    </button>
  );
}

🌐 Example 3: Water Resource Management (React/Next.js)

Location: examples/water-resource-management/

A React/Next.js implementation of the water resource management system, converted from the original static HTML version to provide a modern, maintainable codebase.

Features:

  • βœ… Full Next.js 14 with Pages Router
  • βœ… React hooks for state management
  • βœ… TypeScript for type safety
  • βœ… Same functionality as original HTML version
  • βœ… Production-ready structure
  • βœ… Hot reload development experience

Run Locally:

cd examples/water-resource-management
npm install
npm run dev

Visit http://localhost:3002

Live Demo: https://fhe-water-resource-manager.vercel.app/

Note: The original index.html static version is preserved in the directory for reference.


πŸ“Ή Video Demonstration

Video File: demo.mp4 (located in repository root)

Important: The demo video must be downloaded to view. Streaming is not supported.

How to Access:

  1. Navigate to the GitHub repository root directory
  2. Locate the file named demo.mp4
  3. Click "Download" or "Download raw file"
  4. Open with your media player (VLC, Windows Media Player, etc.)

Video Content: Complete walkthrough of FHEVM SDK usage through the water resource management examples, including:

  • SDK initialization
  • Privacy-preserving water allocation
  • React hooks integration
  • Encrypted data processing
  • Admin and manager workflows

⭐ Example 4: Next.js App Router with Full FHE Architecture

Location: examples/nextjs-fhe-app-router/

A modern Next.js 13+ App Router implementation showcasing a complete, scalable FHE architecture with API routes, custom hooks, and production-ready components.

Features:

  • βœ… Next.js 14 App Router - Modern React Server Components
  • βœ… Complete Architecture - Modular, scalable code structure
  • βœ… API Routes - RESTful endpoints for FHE operations
  • βœ… Custom Hooks - useFHE, useEncryption, useComputation
  • βœ… UI Component Library - Reusable Button, Input, Card components
  • βœ… FHE Components - Provider, demos, key manager
  • βœ… Real-World Examples - Banking and medical use cases
  • βœ… Type-Safe - Complete TypeScript implementation
  • βœ… Production Patterns - Best practices for scalability

Run Locally:

cd examples/nextjs-fhe-app-router
npm install
npm run dev

Visit http://localhost:3002

Architecture Highlights:

API Endpoints:

  • POST /api/fhe/encrypt - Encrypt data
  • POST /api/fhe/decrypt - Decrypt ciphertext
  • POST /api/fhe/compute - Homomorphic computation
  • POST /api/keys - Key generation

Custom Hooks:

// FHE initialization
const { isInitialized, initialize } = useFHE();

// Encryption with loading states
const { encryptWithSDK, encryptWithAPI, isEncrypting } = useEncryption();

// Homomorphic computation
const { compute, add, subtract, compare, result } = useComputation();

Component Structure:

  • UI Components: Button, Input, Card
  • FHE Components: FHEProvider, EncryptionDemo, ComputationDemo, KeyManager
  • Examples: BankingExample, MedicalExample

Code Example:

import { useEncryption } from '@/hooks/useEncryption';
import { Button } from '@/components/ui/Button';

function BankingApp() {
  const { encryptWithSDK, isEncrypting } = useEncryption();

  const handleDeposit = async (amount: number) => {
    // Encrypt sensitive data
    const encrypted = await encryptWithSDK(amount, 'uint32');

    // Send to contract (encrypted!)
    await contract.deposit(encrypted);
  };

  return (
    <Button onClick={() => handleDeposit(1000)} isLoading={isEncrypting}>
      Deposit Confidentially
    </Button>
  );
}

πŸ“Š Example Comparison

Feature Simple Next.js Full Next.js Water Resource Mgmt App Router
Framework Pages Router Pages Router Pages Router App Router
SDK Integration βœ… Basic βœ… Complete βœ… Complete βœ… Complete
Production Ready ❌ Demo only βœ… Yes βœ… Yes βœ… Yes
Architecture Simple Water Management Water Management Full FHE Stack
API Routes ❌ No ❌ No ❌ No βœ… Yes
Custom Hooks ❌ No ❌ No React hooks βœ… Yes
UI Components Basic Inline Inline βœ… Library
Real-World Examples ❌ No βœ… Water βœ… Water βœ… Banking + Medical
TypeScript βœ… Yes βœ… Yes βœ… Yes βœ… Yes
Build Required βœ… Yes βœ… Yes βœ… Yes βœ… Yes
Port 3000 3001 3002 3002
Best For Learning Production App Production App Scalable Apps

Recommendation:

  • Just learning FHE? β†’ Start with Simple Next.js Example
  • Building a production app? β†’ Use Full Next.js Example or Water Resource Management
  • Need scalable architecture? β†’ Use App Router Example ⭐

πŸ“š SDK API Reference

Initialization

import { initFHEVM } from 'fhevm-sdk';

await initFHEVM({
  network: 'sepolia' | 'localhost',
  provider: window.ethereum,  // or ethers provider
  contractAddress?: string    // optional
});

Encryption

import { encrypt } from 'fhevm-sdk';

const encrypted32 = await encrypt.uint32(1000);
const encrypted64 = await encrypt.uint64(1000000);
const encryptedBool = await encrypt.bool(true);
const encryptedAddr = await encrypt.address('0x...');

Decryption

import { decrypt } from 'fhevm-sdk';

// User decryption (with EIP-712 signature)
const value = await decrypt.user(ciphertext, {
  signer: wallet,
  contract: contractAddress
});

// Public decryption (if permitted)
const publicValue = await decrypt.public(ciphertext);

React Hooks

import { useFHEVM, useEncrypt, useDecrypt } from 'fhevm-sdk/react';

// Initialize SDK
const { isReady, isInitializing, error, init } = useFHEVM(config);

// Encryption with loading states
const { encryptUint32, isEncrypting, error } = useEncrypt();

// Decryption with loading states
const { decryptUser, isDecrypting, error } = useDecrypt();

// Contract interaction
const { contract, isLoading, error } = useContract({
  address: '0x...',
  abi: contractABI,
  provider: provider
});

πŸ—οΈ Building Your Own dApp

Step 1: Install SDK

npm install fhevm-sdk

Step 2: Use in Your App

// app.tsx or page.tsx
import { useFHEVM, useEncrypt } from 'fhevm-sdk/react';

export default function MyApp() {
  const { isReady } = useFHEVM({
    network: 'sepolia',
    provider: window.ethereum
  });

  const { encryptUint32 } = useEncrypt();

  const handleEncrypt = async () => {
    const encrypted = await encryptUint32(1000);
    console.log('Encrypted:', encrypted);
  };

  if (!isReady) return <div>Initializing FHEVM...</div>;

  return <button onClick={handleEncrypt}>Encrypt</button>;
}

Step 3: Deploy Smart Contract

// MyContract.sol
import { FHE, euint32 } from "@fhevm/solidity/lib/FHE.sol";

contract MyConfidentialContract {
    mapping(address => euint32) private balances;

    function deposit(euint32 encryptedAmount) external {
        balances[msg.sender] = encryptedAmount;
        FHE.allowThis(encryptedAmount);
        FHE.allow(encryptedAmount, msg.sender);
    }

    function getBalance() external view returns (euint32) {
        return balances[msg.sender];
    }
}

πŸ“‹ Integration Templates

Want to integrate FHEVM SDK into your existing project? Check out our framework-specific templates:

Available Templates

Framework Template Description
Next.js templates/nextjs/ Complete Next.js integration guide with App Router & Pages Router examples
React templates/react/ React integration for CRA, Vite, and other React setups
Vue templates/vue/ Vue 3 integration using Composition API composables
Node.js templates/nodejs/ Backend services, CLI tools, and serverless functions

Quick Template Access

# View Next.js template
cat templates/nextjs/README.md

# View React template
cat templates/react/README.md

# View Vue template
cat templates/vue/README.md

# View Node.js template
cat templates/nodejs/README.md

Each template includes:

  • βœ… Installation instructions
  • βœ… Configuration examples
  • βœ… Code snippets
  • βœ… Best practices
  • βœ… Links to working examples

See templates/README.md for complete overview


🎨 Use Cases

1. Confidential Voting

  • Encrypted votes
  • Public tallying without revealing individual choices
  • Privacy-preserving governance

2. Secret Auctions

  • Hidden bids until reveal
  • Fair price discovery
  • Trustless auction mechanisms

3. Private DeFi

  • Confidential balances
  • Hidden transaction amounts
  • Privacy-preserving swaps
  • Dark pools

4. Confidential Resource Allocation

  • Hidden demands (like water management)
  • Fair distribution algorithms
  • Privacy in supply chains

5. Secure Identity & Credentials

  • Private credentials
  • Selective disclosure
  • Zero-knowledge proofs
  • Compliance without exposure

6. Healthcare Data

  • Encrypted patient records
  • Privacy-preserving research
  • Confidential diagnostics

πŸ“Š Performance & Gas Costs

FHE Operation Costs (Sepolia)

Operation Gas Cost Notes
encrypt.uint32() ~50,000 Client-side + contract
FHE.add() ~75,000 On-chain computation
FHE.gt() ~80,000 Encrypted comparison
decrypt.user() ~30,000 With EIP-712 signature

Optimization Tips

βœ… Minimize FHE operations - Cache encrypted values where possible βœ… Batch operations - Process multiple items together βœ… Use smallest types - euint32 vs euint64 vs euint128 βœ… Strategic encryption - Only encrypt sensitive data


πŸ§ͺ Testing & Development

Run Tests

# From root
npm test

# From parent directory (smart contracts)
cd ../../
npm run test
npm run test:coverage

Local Development

# Start Next.js dev server
npm run dev

# Build SDK
npm run build

# Compile contracts
npm run compile

🌐 Live Deployment

Smart Contract (Example)

Network: Ethereum Sepolia Testnet Contract Address: 0x4E2c3faE5165E4d5f9E2dEcFEA50e84399157b76 Explorer: View on Etherscan

Next.js Demo

URL: https://fhe-water-resource-manager.vercel.app/ Status: βœ… Live and operational


πŸ“š Complete Documentation

Document Description
README.md This file - SDK overview
templates/ Framework integration templates (Next.js, React, Vue, Node.js)
SUBMISSION.md Competition submission summary
QUICK_START.md 5-minute quick start guide
FINAL_CHECKLIST.md Requirements verification
FILE_MANIFEST.md Complete file listing
docs/ Additional documentation

πŸ’» Tech Stack

Core SDK

  • TypeScript - Type-safe SDK development
  • Zama FHEVM - FHE smart contract library
  • Ethers.js v6 - Blockchain interaction
  • React - Optional hooks adapter

Example Application

  • Next.js 14.x - React framework
  • React 18.x - UI library
  • Tailwind CSS - Styling
  • TypeScript - Type safety
  • MetaMask - Wallet integration

Development Tools

  • Hardhat - Smart contract framework
  • Mocha/Chai - Testing
  • ESLint - Code linting
  • Prettier - Code formatting

πŸ”— Related Projects & Resources

Example Applications

FHE Confidential Water Resource Management - Privacy Water Allocation

FHE Resources

Zama FHEVM Documentation

Development Resources


🀝 Contributing

We welcome contributions!

# Fork and clone
git clone https://github.com/your-fork/fhevm-react-template.git
cd fhevm-react-template

# Install dependencies
npm install

# Make changes and test
npm run dev

# Submit PR

πŸ“„ License

MIT License - see LICENSE file.


πŸ™ Acknowledgments

  • Zama - For pioneering FHE technology and FHEVM
  • Ethereum Community - For blockchain infrastructure
  • wagmi - For API design inspiration
  • Next.js - For excellent React framework
  • All Contributors - For improving this SDK

πŸ“ž Support & Links

GitHub Repository: https://github.com/OsbaldoSchmeler/fhevm-react-template

Example Application: https://github.com/OsbaldoSchmeler/FHEWaterResourceManager

Live Demo: https://fhe-water-resource-manager.vercel.app/

Issues: GitHub Issues

Discussions: GitHub Discussions

Video Demo: Download demo.mp4 from repository


πŸš€ Ready to Build?

Start with the Next.js example:

npm install && npm run dev

Or integrate SDK in your existing app:

npm install fhevm-sdk

πŸ” Built for Privacy-Preserving Applications

Universal β€’ Developer-Friendly β€’ Production-Ready

Make Confidential Computing Simple with FHEVM SDK

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  • CSS 1.3%
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