ROSCA-Guard

Problem Statement

ROSCA-Guard is a decentralized application that revolutionizes traditional Rotating Savings and Credit Associations (ROSCAs) by integrating blockchain technology with privacy-preserving identity verification. The platform addresses critical trust issues in traditional ROSCAs by implementing Self Protocol's zero-knowledge proof identity verification, ensuring all participants are verified humans while maintaining their privacy. The application enables users to create and join ROSCA circles with verified members only, using PYUSD for automated monthly contributions and payouts. Each circle operates with smart contract automation on Ethereum, while KYC verification is handled on Celo blockchain through Self Protocol's identity verification system. This cross-chain architecture provides both security and cost-efficiency. Key features include: Real-time identity verification using passport or Aadhaar documents through Self Protocol's zero-knowledge proofs, automated PYUSD payments with smart contract enforcement, reputation-based payout selection algorithms, yield generation through DeFi protocol integration, and comprehensive analytics for platform performance tracking. The platform solves traditional ROSCA problems such as default risk, lack of transparency, manual coordination overhead, and limited scalability, while maintaining the community-driven spirit of traditional savings circles. Users can participate in circles globally or join region-specific groups, with all transactions being transparent and automated through blockchain technology.

Solution

ROSCA-Guard is built using a sophisticated multi-chain architecture combining cutting-edge technologies to deliver a seamless user experience. The frontend is developed with React, TypeScript, and Vite, styled with Tailwind CSS, and integrates RainbowKit for wallet connectivity supporting multiple Ethereum wallets.The core innovation lies in our Self Protocol integration for privacy-preserving KYC verification. We utilize Self Protocol's @selfxyz/core and @selfxyz/qrcode SDKs to implement zero-knowledge proof verification supporting both passport and Aadhaar documents. The frontend displays QR codes for mobile app verification, while the backend processes proofs using SelfBackendVerifier with configurable age and nationality requirements.Our cross-chain architecture deploys KYC verification contracts on Celo blockchain for cost-efficient identity verification, while ROSCA circle contracts operate on Ethereum mainnet for PYUSD integration. The backend Express.js server with TypeScript coordinates between chains using ethers.js providers for both networks.Smart contracts are developed in Solidity 0.8.28 using Foundry framework, featuring ROSCACircle contracts with automated payment cycles, ROSCAFactory for circle creation and management, KYCVerifier contract extending Self Protocol's SelfVerificationRoot, and YieldManager for DeFi integration generating additional returns.The technical stack includes comprehensive error handling and validation using express-validator, CORS and rate limiting for API security, automated deployment scripts for contract verification, and real-time event monitoring across both blockchain networks.Notable technical innovations include dynamic age calculation from passport/Aadhaar birth dates using custom DateParser library, reputation-based recipient selection algorithms considering contribution history and timeliness, automated yield distribution from integrated DeFi protocols, and batch eligibility checking for multiple users simultaneously.The application successfully bridges traditional finance concepts with modern blockchain technology, providing a trust-minimized yet user-friendly savings circle experience powered by Self Protocol's privacy-preserving identity verification.