<p align="center">
  <img src="assets/logo.png" alt="QPQ logo" width="200">
</p>

# QPQ — quicproquo

[![CI](https://github.com/nickvidal/quicproquo/actions/workflows/ci.yml/badge.svg)](https://github.com/nickvidal/quicproquo/actions/workflows/ci.yml)

> End-to-end encrypted messaging over **QUIC + TLS 1.3 + MLS** (RFC 9420), written in Rust.

The server never sees plaintext. Every byte on the wire is protected by a QUIC
transport secured with TLS 1.3 (`quinn` + `rustls`). The inner **MLS** layer
provides forward secrecy, post-compromise security, and ratcheted group key
agreement across any number of participants. Messages are framed with
**Cap'n Proto** for zero-copy, schema-versioned serialisation.

```
┌─────────────────────────────────────────────┐
│          Application / MLS ciphertext        │  <- group key ratchet (RFC 9420)
├─────────────────────────────────────────────┤
│              Cap'n Proto RPC                │  <- typed, schema-versioned framing
├─────────────────────────────────────────────┤
│        QUIC + TLS 1.3 (quinn/rustls)        │  <- mutual auth + transport secrecy
└─────────────────────────────────────────────┘
```

| Property | Mechanism |
|---|---|
| Transport confidentiality | TLS 1.3 over QUIC (rustls) |
| Transport authentication | TLS 1.3 server cert (self-signed or CA) |
| Group key agreement | MLS `MLS_128_DHKEMX25519_AES128GCM_SHA256_Ed25519` |
| Post-compromise security | MLS epoch ratchet |
| Forward secrecy | Per-epoch key schedule |
| Identity | Ed25519 (MLS credential + leaf node signature) |
| Password auth | OPAQUE (password never sent to server) |
| Post-quantum readiness | X25519 + ML-KEM-768 hybrid KEM envelope |
| Local storage encryption | SQLCipher + Argon2id + ChaCha20-Poly1305 |
| Message framing | Cap'n Proto (unpacked wire format) |

---

## Features

### Core

- **Interactive REPL** — multi-conversation chat with auto-register, auto-login, slash commands, background polling, and message history
- **1:1 DMs** — dedicated channels with server-enforced membership authorization
- **Multi-party groups** — N-member MLS groups with Commit fan-out and epoch sync
- **OPAQUE authentication** — password-authenticated key exchange (password never leaves the client)
- **Encrypted local storage** — SQLCipher database + encrypted session tokens (Argon2id + ChaCha20-Poly1305)
- **Persistent state** — server and client survive restarts; SQLite/SQLCipher or file-backed storage
- **Self-DM notepad** — send messages to yourself (local-only, no server round-trip)
- **Certificate pinning** — pass the server cert as `--ca-cert` to trust only that server
- **Federation** — server-to-server message relay via Cap'n Proto RPC over QUIC with mTLS
- **mDNS discovery** — servers announce `_quicproquo._udp.local.`; clients auto-discover nearby nodes
- **Sealed sender mode** — optional anonymous enqueue (sender identity inside MLS ciphertext only)
- **Prometheus metrics** — `--metrics-listen` exposes `/metrics` endpoint for monitoring
- **Dynamic plugin system** — load `.so`/`.dylib` plugins at runtime via `--plugin-dir`
- **Safety numbers** — `/verify <username>` for out-of-band key verification (60-digit numeric code)
- **Transcript export** — encrypted, tamper-evident message archives with hash-chain integrity verification
- **20 CLI subcommands** — `register-user`, `login`, `create-group`, `invite`, `join`, `send`, `recv`, `chat`, `repl`, `export`, `export-verify`, and more

### REPL slash commands

| Command | Description |
|---|---|
| `/dm <username>` | Start a 1:1 DM with a peer |
| `/create-group <name>` (or `/cg`) | Create a new group |
| `/invite <username>` | Add a member to the current group |
| `/remove <username>` | Remove a member from the current group |
| `/join` | Join a pending group invitation |
| `/leave` | Leave the current group |
| `/switch @user` or `/switch #group` | Switch active conversation |
| `/list` or `/ls` | List all conversations |
| `/members` | Show group members |
| `/history [count]` (or `/hist`) | Show message history (default 20) |
| `/verify <username>` | Compare safety numbers with a peer |
| `/update-key` (or `/rotate-key`) | Rotate your MLS key material |
| `/mesh peers` | Scan for nearby qpq nodes via mDNS |
| `/mesh server <host:port>` | Note a discovered server address |
| `/whoami` | Show identity and group status |
| `/help` | Command reference |
| `/quit` | Exit |

### Experimental / proof-of-concept

- **Tauri 2 GUI** (`quicproquo-gui`) — foundational desktop app shell; not feature-complete
- **Mobile FFI** (`quicproquo-mobile`) — C API for QUIC connection migration (wifi to cellular)
- **P2P transport** (`quicproquo-p2p`) — iroh-based direct peer-to-peer messaging with NAT traversal (feature-gated behind `--features mesh`)
- **Bot framework** (`quicproquo-bot`) — programmable bot client

---

## Quick start

```bash
# Prerequisites: Rust 1.77+, capnp CLI
brew install capnp          # macOS
# apt-get install capnproto # Debian/Ubuntu

# Build (excludes GUI — requires GTK system libs)
cargo build --bin qpq-server --bin qpq

# Run tests
cargo test --workspace --exclude quicproquo-gui

# Start the server (port 7000 by default, auto-generates self-signed cert)
cargo run --bin qpq-server -- --allow-insecure-auth

# Interactive REPL (auto-registers and logs in)
cargo run --bin qpq -- repl --username alice --password mypass
```

### REPL quickstart (two terminals)

```bash
# Terminal 1
qpq repl --username alice --password secretA

# Terminal 2
qpq repl --username bob --password secretB

# In Alice's REPL:
/dm bob
Hello from Alice!

# Bob sees: [alice] Hello from Alice!
```

### Server configuration (TOML)

```bash
cat > qpq-server.toml <<'EOF'
listen = "0.0.0.0:7000"
data_dir = "data"
tls_cert = "data/server-cert.der"
tls_key = "data/server-key.der"
auth_token = "your-strong-token-here"
store_backend = "sql"       # or "file"
db_path = "data/qpq.db"
db_key = "your-db-encryption-key"
metrics_listen = "0.0.0.0:9090"
metrics_enabled = true
# Federation (optional)
# federation_enabled = true
# federation_domain = "chat.example.com"
# federation_listen = "0.0.0.0:7001"
# Plugin loading (optional)
# plugin_dir = "/etc/qpq/plugins"
EOF
cargo run --bin qpq-server -- --config qpq-server.toml
```

> **Production:** use a strong `QPQ_AUTH_TOKEN`, set `QPQ_DB_KEY` when using `store_backend = "sql"`, and provide real TLS certificates (the server refuses to auto-generate certs in production mode).

See the [full demo walkthrough](docs/src/getting-started/demo-walkthrough.md) for a step-by-step guide.

---

## Crate layout

| Crate | Purpose |
|---|---|
| `quicproquo-core` | MLS group operations, hybrid KEM, OPAQUE auth, crypto primitives |
| `quicproquo-proto` | Cap'n Proto schemas and generated RPC code |
| `quicproquo-server` | QUIC server, NodeService RPC, storage backends, federation, plugins |
| `quicproquo-client` | CLI + REPL, session management, conversation store |
| `quicproquo-plugin-api` | C-compatible plugin hook API (`HookVTable`) |
| `quicproquo-kt` | Key transparency / Merkle-log identity bindings |
| `quicproquo-bot` | Programmable bot client framework |
| `quicproquo-gen` | Code generation utilities |
| `quicproquo-gui` | Tauri 2 desktop app (experimental, requires GTK) |
| `quicproquo-mobile` | C FFI for mobile connection migration (experimental) |
| `quicproquo-p2p` | iroh-based P2P transport (feature-gated, `--features mesh`) |

---

## CI pipeline

GitHub Actions runs on every push and PR:

- `cargo fmt --check` — formatting
- `cargo build --workspace` — full build
- `cargo test --workspace` — 103+ tests (core, server, client, E2E, doctests)
- `cargo clippy --workspace` — lint
- `cargo deny check` — license and advisory audit
- `cargo audit` — vulnerability scan
- `cargo tarpaulin` — code coverage (uploaded as artifact)
- `docker build` — container image validation

---

## Milestones

| # | Name | Status | What it adds |
|---|------|--------|--------------|
| M1 | QUIC/TLS transport | **Done** | QUIC + TLS 1.3 endpoint, length-prefixed framing, Ping/Pong |
| M2 | Authentication Service | **Done** | Ed25519 identity, KeyPackage generation, AS upload/fetch |
| M3 | Delivery Service + MLS groups | **Done** | DS relay, `GroupMember` create/join/add/send/recv |
| M4 | Group CLI subcommands | **Done** | Persistent CLI, OPAQUE login, 20 subcommands |
| M5 | Multi-party groups | **Done** | N > 2 members, Commit fan-out, `send --all`, epoch sync |
| M6 | Persistence + REPL | **Done** | SQLite/SQLCipher, interactive REPL, DM channels, encrypted local storage |
| M7 | Post-quantum MLS | **Planned** | Hybrid X25519 + ML-KEM-768 integrated into MLS ciphersuite |

M7 note: the hybrid KEM envelope is already implemented and tested (10 tests passing). What remains is integrating it into the OpenMLS CryptoProvider so all MLS key material gets post-quantum confidentiality.

---

## Roadmap

See [ROADMAP.md](ROADMAP.md) for the full phased plan. Summary:

| Phase | Focus | Status |
|-------|-------|--------|
| 1 | Production hardening (unwrap removal, secure defaults, Docker) | In progress |
| 2 | Test and CI maturity | Partially done |
| 3 | Client SDKs (Go, Python, WASM, FFI, WebTransport) | Planned |
| 4 | Trust and security (audit, key transparency, PQ MLS) | Planned |
| 5 | Features and UX (multi-device, offline queue, file transfer) | Planned |
| 6 | Scale and operations (horizontal scaling, observability) | Planned |
| 7 | Platform expansion (mobile, web, federation, sealed sender) | Planned |
| 8 | Freifunk / community mesh networking | F0-F2 done |
| 9 | Developer experience and community growth | Planned |

### Recently completed

- **Federation routing** — server-to-server message relay with mTLS
- **mDNS discovery** — servers advertise on local network, clients discover peers
- **P2P transport** — iroh-based direct messaging re-included in workspace (`--features mesh`)
- **CI pipeline** — fmt, build, test, clippy, deny, audit, coverage, Docker build
- **Plugin system** — dynamic `.so`/`.dylib` loading with C-compatible hook API
- **Safety numbers** — Signal-style 60-digit verification codes
- **Transcript export** — encrypted, hash-chained message archives

---

## Building without the GUI

The GUI crate requires GTK system libraries. To build just the server and client:

```bash
cargo build --bin qpq-server --bin qpq
```

To build the client with mesh/P2P support:

```bash
cargo build -p quicproquo-client --features mesh
```

---

## Documentation

Full documentation is available as an **mdBook** in [`docs/`](docs/):

```bash
cargo install mdbook     # once
mdbook serve docs        # http://localhost:3000
```

- **[Architecture Overview](docs/src/architecture/overview.md)** — two-service model, dual-key design, crate layout
- **[Protocol Deep Dives](docs/src/protocol-layers/overview.md)** — QUIC/TLS 1.3, Cap'n Proto, MLS, Hybrid KEM
- **[Cryptographic Properties](docs/src/cryptography/overview.md)** — forward secrecy, post-compromise security, PQ readiness, threat model
- **[Design Rationale](docs/src/design-rationale/overview.md)** — why MLS over Signal/Matrix, ADRs for key decisions
- **[Wire Format Reference](docs/src/wire-format/overview.md)** — annotated Cap'n Proto schemas
- **[Getting Started](docs/src/getting-started/prerequisites.md)** — build, run, demo walkthrough
- **[Roadmap](docs/src/roadmap/milestones.md)** — milestones, production readiness, future research
- **[Future Improvements](docs/FUTURE-IMPROVEMENTS.md)** — prioritised list of security, ops, and feature improvements

---

## Security

This is a **research project** and has not undergone a formal third-party audit. See the [threat model](docs/src/cryptography/threat-model.md) and [security audit](docs/SECURITY-AUDIT.md) for details.

- The server only routes opaque ciphertexts by recipient key — it never sees plaintext.
- OPAQUE ensures passwords never leave the client.
- Local databases are encrypted with SQLCipher when a password is provided.
- Session tokens are encrypted at rest (Argon2id key derivation + ChaCha20-Poly1305).
- **Certificate pinning:** pass the server cert as `--ca-cert` so the client trusts only that server.
- **Sealed sender:** optional mode where the server cannot see who sent a message.
- **Dependency checks:** CI runs `cargo deny check` and `cargo audit` on every PR.

---

## License

MIT
