FHE2P

MA Description

Go in as much detail as you can about what this project is. Please be as clear as possible!

This project, named FHE2P (Fully Homomorphic Encryption Peer-to-Peer), is a decentralized voucher marketplace implemented as a smart contract on a blockchain that supports Fully Homomorphic Encryption (FHE). Here's a detailed description of the project:

Core Concept: It allows for the creation, sale, resale, and redemption of encrypted vouchers. The system uses FHE to maintain privacy and security of sensitive voucher data. Key Features: Voucher Creation: Administrators can create vouchers with encrypted codes and PINs. Buying and Reselling: Users can purchase vouchers directly or buy resold vouchers. Voucher Revelation: Owners can reveal their vouchers using a PIN. Metadata Retrieval: Public voucher information can be accessed without revealing private data. Privacy and Security: Voucher codes and PINs are stored in encrypted form. FHE allows for computations on encrypted data without decryption. Only the rightful owner can reveal a voucher's contents. Economic Model: Platform fees are applied to resold vouchers. Stablecoin integration for payments. Voucher Structure: Each voucher contains: Encrypted code and PIN Price Expiry date Owner and seller information Public metadata (image URL, description) User Interactions: Buying: Users can purchase available vouchers. Reselling: Owners can resell their unrevealed vouchers. Revealing: Owners can reveal their vouchers using the correct PIN. Viewing: Users can view available vouchers and their own purchased vouchers. Administrative Functions: Voucher listing Platform fee adjustment Emergency controls (pausing, fund withdrawal) Technical Implementation: Uses Solidity with FHE extensions. Integrates OpenZeppelin libraries for standard functionalities. Implements custom FHE operations for encrypted data handling. Use Cases: Gift card marketplaces Ticket reselling platforms Confidential coupon systems This project aims to create a secure, private, and flexible system for voucher trading, leveraging blockchain technology and advanced cryptography to ensure user privacy and data security while maintaining the functionality of a dynamic marketplace.

This FHE2P (Fully Homomorphic Encryption Peer-to-Peer) project was built using a combination of cutting-edge blockchain technologies and cryptographic techniques. Here's a detailed breakdown of how it was made:

1. Core Technology Stack:

   • Solidity (v0.8.20): The primary smart contract language.
   • Fhenix Protocol: Leveraged for Fully Homomorphic Encryption capabilities.
   • OpenZeppelin Contracts: Used for standard, secure implementations of common contract functionality.

2. FHE Integration:

   • Imported "@fhenixprotocol/contracts/FHE.sol" to access FHE operations.
   • Utilized encrypted types like euint256, euint32, ebool, and eaddress for sensitive data.
   • Implemented FHE operations (e.g., FHE.eq, FHE.lt, FHE.add) for computations on encrypted data.

3. Voucher Structure:

   • Designed a Voucher struct combining encrypted and public fields.
   • Used euint256 for encrypted voucher codes and euint64 for PINs.
   • Stored public metadata (price, expiry date, image URL, description) for easy retrieval.

4. Smart Contract Architecture:

   • Inherited from OpenZeppelin's Ownable, Pausable, and ReentrancyGuard for security.
   • Implemented SafeERC20 for secure token transfers.
   • Created a mapping of voucher IDs to Voucher structs for efficient storage and retrieval.

5. Key Functionalities:

   • Voucher Listing: Admins can list vouchers with encrypted and public data.
   • Buying Mechanism: Implemented separate functions for buying new and resold vouchers.
   • Reselling: Allows users to resell their unrevealed vouchers.
   • Revelation: Users can reveal vouchers using encrypted PINs.

6. Privacy-Preserving Features:

   • Used FHE.sealoutput for secure revelation of voucher codes.
   • Implemented encrypted comparisons for expiry checks and ownership verification.

7. Metadata Handling:

   • Created a separate VoucherMetaData struct for public information.
   • Implemented functions to retrieve metadata for available vouchers and user-owned vouchers.

8. Economic Model:

   • Integrated a platform fee system for resold vouchers.
   • Used SafeERC20 for secure stablecoin transfers.

9. Security Measures:

   • Implemented pause functionality for emergency situations.
   • Added nonReentrant modifiers to prevent reentrancy attacks.
   • Used require statements and FHE.req for validation checks.

10. Optimization Techniques:

    • Two-pass approach in metadata retrieval functions to optimize gas usage.
    • Used uint32 for prices and expiry dates to save storage space.

11. Notable "Hacky" Solutions:

    • Used FHE.decrypt within view functions to check encrypted conditions, allowing for gas-efficient queries of encrypted data.
    • Implemented a custom approach to handle encrypted booleans (ebool) in conditional logic.

12. Partner Technologies:

    • Fhenix Protocol: Enabled FHE operations, significantly enhancing the privacy and security of the system.
    • OpenZeppelin: Provided battle-tested implementations of common contract patterns, improving security and reducing development time.

13. Testing and Deployment:

    • Developed on a local blockchain environment supporting FHE operations.
    • Planned for deployment on Fhenix's testnet for real-world testing.

This project demonstrates a novel approach to building a privacy-preserving marketplace by leveraging FHE in smart contracts. The combination of blockchain technology and advanced cryptography allows for a secure, private, yet transparent system for voucher trading.