PeerNet: A Decentralized File Sharing Proof-of-Concept

PeerNet is a robust proof-of-concept for a decentralized peer-to-peer (P2P) file sharing system, drawing inspiration from BitTorrent. It demonstrates how individual "peers" can directly exchange file data, while a central "tracker" orchestrates discovery, manages authentication, and incentivizes network participation through a reputation and token-based economy.

✨ Features

• Decentralized File Transfer: File chunks are transferred directly between peers using gRPC, eliminating central bottlenecks for data.
• Centralized Tracker for Discovery: A dedicated tracker service helps peers find each other and discover available file chunks.
• JWT-Based Authentication: Secure registration and authenticated API interactions between peers and the tracker using JSON Web Tokens (JWTs).
• Reputation & Token Economy:
  • Peers receive a reputation_score and token_balance.
  • Successful file chunk uploads increase the uploader's reputation and tokens.
  • Failed uploads decrease reputation and tokens, incentivizing reliable behavior.
  • File lookups prioritize peers with higher reputation scores.
• File Chunking & Hashing: Files are split into fixed-size chunks, with SHA256 hashes for both individual chunks and the entire file, ensuring data integrity.
• Containerized Deployment: All services (tracker, peers, database) are Dockerized and orchestrated using Docker Compose for easy setup and isolation.
• Command-Line Interface (CLI): User-friendly CLI for peer registration, file sharing, and downloading.

🏛️ Architecture

PeerNet is comprised of two primary, independently containerized services:

1. Tracker Service (Go, Gin, PostgreSQL):
   • Role: Acts as the central directory. It stores metadata about registered peers, available files, and which peers possess which file chunks. It handles peer registration, file announcements, and file lookups.
   • Authentication: Secures its API endpoints using JWTs issued upon peer registration.
   • Reputation Engine: A background process that periodically updates peer reputation scores and token balances based on feedback received from downloaders.
   • Database: Uses PostgreSQL to persist all network state, including peer profiles, file metadata, and reputation events.
2. Peer Client Service (Go, gRPC, Cobra CLI):
   • Role: The active participants in the P2P network. Peers can share local files and download files from other peers.
   • CLI: Provides commands for register (with the tracker), share (a local file), and download (a file by its hash).
   • File Management: Chunks files for sharing and reassembles downloaded chunks.
   • gRPC Server: When sharing, a peer starts a gRPC server to serve its file chunks directly to other requesting peers.
   • Tracker Interaction: Communicates with the tracker via authenticated HTTP requests (using JWTs) for registration, announcing shared chunks, and looking up peers for downloads.
   • Direct P2P Transfer: Initiates direct gRPC connections to other peers to request and receive file chunks.
   • Feedback Mechanism: Reports success or failure of chunk downloads to the tracker, contributing to the reputation system.

Communication Flow:

• Peer ↔ Tracker: Authenticated HTTP (REST API) for registration, file announcements, lookups, and feedback.
• Peer ↔ Peer: Direct gRPC for high-performance file chunk transfer.

🛠️ Technologies Used

• Go (Golang): Primary programming language for both Tracker and Peer services.
• Docker & Docker Compose: For containerization, orchestration, and local development environment setup.
• Gin Web Framework: For building the Tracker's RESTful API.
• PostgreSQL: Relational database for the Tracker's persistent storage.
• gRPC: High-performance RPC framework for peer-to-peer chunk transfers.
• JWT (JSON Web Tokens): For secure authentication between peers and the tracker.
• Cobra CLI: For building the Peer client's command-line interface.
• Bcrypt: For secure password hashing.

📺 Demo Video

A comprehensive demo video showcasing PeerNet's functionality and architecture will be embedded here soon.

💡 Future Improvements (Potential Areas)

• TLS/SSL Encryption: Implement TLS for all gRPC and HTTP communications for enhanced security.
• NAT Traversal: Integrate STUN/TURN/ICE for peers to connect across various network topologies.
• Concurrent & Resumable Downloads: Optimize downloader for parallel chunk fetching from multiple peers and support resuming interrupted downloads.
• Advanced Peer Discovery: Explore Distributed Hash Tables (DHTs) for a truly decentralized peer discovery mechanism, reducing reliance on a single tracker.
• UI/Dashboard: Develop a simple web UI for the tracker to visualize network activity, peer status, and file availability.