Architecture¶

Radix Relay implements a layered architecture for hybrid mesh communications.

System Overview¶

┌─────────────────────────────────────────────┐
│          GUI/TUI Interface                  │
└─────────────────┬───────────────────────────┘
                  │
┌─────────────────▼───────────────────────────┐
│       Signal Protocol Encryption            │
│  (X3DH + Double Ratchet + Kyber)            │
└─────────────────┬───────────────────────────┘
                  │
┌─────────────────▼───────────────────────────┐
│          Hybrid Routing Layer               │
│   (Internet-preferred, mesh fallback)       │
└─────────────────┬───────────────────────────┘
                  │
        ┌─────────┴─────────┐
        │                   │
┌───────▼──────┐     ┌──────▼────────┐
│    Nostr     │     │      BLE      │
│  Transport   │     │   Transport   │
└──────────────┘     └───────────────┘

Key Components¶

User Interface Layer¶

Graphical UI (GUI) - Modern graphical interface built with Slint framework:

Cross-platform support (Windows, macOS, Linux)
Message scrolling with auto-scroll
Bundled fonts for consistent appearance

Terminal UI (TUI) - Command-line interface for headless environments and SSH sessions.

Both interfaces share the same backend event system and provide identical functionality.

Signal Protocol ¶

End-to-end encryption with forward and future secrecy using X3DH key agreement and Double Ratchet algorithm.

Transport Layer ¶

Unified interface for multiple transport mechanisms (Nostr, BLE, and future protocols).

Hybrid Routing ¶

Intelligent routing that prefers internet connectivity but seamlessly falls back to mesh networking.

Design Principles¶

Security First - All messages encrypted end-to-end
Resilient - Works with partial infrastructure
Modular - Clean separation between layers
Extensible - Easy to add new transports