path: root/CLAUDE.md

# MeshBay — Project Conventions

## What this project is

MeshBay is a decentralized peer-to-peer platform for file sharing, video streaming, and group messaging.
See `docs/meshbay-draft-v3.md` for the architecture specification.

## Repository structure

```
meshbay/
├── packages/
│   ├── meshbay-common/   # Shared crypto + protocol — python3-meshbay-common RPM
│   ├── meshbay-hub/      # Hub server (FastAPI + PostgreSQL) — meshbay-hub RPM
│   └── meshbay-node/     # Node daemon + local UI — meshbay-node RPM
├── poc/                  # POC spike scripts (reference, not production)
├── docs/                 # Architecture drafts and POC plans
├── packaging/            # RPM spec files, DEB control files, systemd units
└── QE/                   # NOT versioned (.gitignore) — test artefacts, credentials, demos
    ├── demo-v1/          #   Scripts démo opérationnels (setup_demo.py, run_node.py, download.py)
    ├── spikes/           #   Expérimentations futures (remplace ~/draft/)
    └── server-state/     #   Inventaire de ce qui tourne sur meshbay.org
```

**Règle QE/** : tout test sur meshbay.org doit ouvrir le port UFW, tester, et
fermer le port + tuer les processus dans le MÊME bloc de commandes.
Jamais de processus orphelins ni de ports ouverts après un test.

## Python environment

- **Minimum Python:** 3.12
- **Build backend:** hatchling (per package `pyproject.toml`)

```bash
# Créer le venv (--clear si recréation sur une autre machine/OS)
python3 -m venv .venv --clear
source .venv/bin/activate

# Toutes les dépendances sont déclarées dans les pyproject.toml — un seul pip install suffit
pip install -e packages/meshbay-common -e packages/meshbay-hub -e packages/meshbay-node
pip install pytest pytest-asyncio aiosqlite   # extras dev
```

Les deps clés (aioquic, watchdog, fastapi, blake3, etc.) sont dans les `pyproject.toml`
et installées automatiquement. Ne pas ajouter manuellement des packages sans les déclarer
dans le bon `pyproject.toml`.

> **Ne jamais copier `.venv/` entre machines d'OS différents.** Si rsync depuis Fedora vers Ubuntu,
> exclure `.venv/` et recréer sur la cible avec `python3 -m venv .venv --clear`.
> Sans `--clear`, `certifi.where()` pointe vers un chemin Fedora inexistant sur Ubuntu → `FileNotFoundError`.

```bash
# Lancer les tests
.venv/bin/pytest
```

## Code conventions

- **Linter/formatter:** ruff (`uv run ruff check .` / `uv run ruff format .`)
- **Line length:** 100
- **Type hints:** required on all public functions
- **Comments:** only when the WHY is non-obvious; no docstrings restating the function name
- **No prints in library code** — use `logging` module

## Versioning

### Package versions (SemVer)
- Format: `MAJOR.MINOR.PATCH`
- Pre-1.0: breaking changes bump MINOR, not MAJOR
- All three packages share the same version number (released together)

### Protocol versions (independent)
- MNP: `0.1` → bumped independently of package version
- MHP: `0.1` → bumped independently of package version
- Every wire message carries a `v` field
- Breaking change → MAJOR bump; backward-compatible → MINOR bump
- N-2 MINOR backward compatibility guaranteed

## Commit messages (Conventional Commits)

```
feat(node): add directory watcher with watchdog
fix(hub): include jti in all JWT tokens
chore(common): add Argon2id calibration to crypto.py
docs: update draft v3 with POC findings
test(common): add wrap/unwrap GEK round-trip test
```

Types: `feat`, `fix`, `chore`, `docs`, `test`, `refactor`, `perf`
Scope: `hub`, `node`, `common`, or omitted for cross-cutting

## Security rules

- **Never commit private keys** (hub_private.pem, *.key, unlock.key, keystore.enc)
- **Never commit QE/** — credentials, test keys, demo data go there
- **Never log GEK, private keys, or plaintext passwords** — even at DEBUG level
- **meshbay.org is internet-facing** — open port → test → close port + kill processes in same block

## First security review (2026-08-10) — see `first-review.md`

**Critical (before Phase 7):**
- **C1** Chat: Sender Keys protocol, NOT shared Double Ratchet (pairwise protocol
  would cause key/nonce reuse in group context). `ratchet.py` kept for future 1:1 DM.
- **C2** JWT must carry `"groups": [group_ids]` claim. Node MNP handshake must verify
  group membership before serving content. Without this, any authenticated user
  accesses any group.

**Significant (Phase 7-8):**
- **S1** Admin revocation endpoint has no authz check ✅ DONE (Phase 8.1 — config-based require_admin)
- **S2** Email stored in plaintext (spec says encrypted at rest) ✅ DONE (Phase 8.2 — AES-256-GCM, HKDF from hub key)
- **S3** jti denylist push via hub→node WebSocket → Phase 7.2
- **S4** AES-GCM keystore IV fixed: 128-bit → 96-bit (NIST SP 800-38D) ✅ DONE
- **S5** Refresh token rotation (one-time use) ✅ DONE (Phase 8.3 — family-based reuse detection)

**Node sovereignty (2026-08-12):**
- **NS1** GEK-HMAC proof in handshake — blocks hub admin from accessing any group content ✅ DONE
- **NS2** Ed25519 challenge-response for admin operations — blocks hub admin impersonation ✅ DONE
- **NS3** `gek_req` endpoint removed — node never serves GEK in plaintext ✅ DONE
- **NS4** `admin_pk_ed25519` pinned in node.toml — auto-pinned from keystore ✅ DONE
- **NS5** DTLS channel binding in GEK-HMAC — `HMAC(GEK, nonce || offer_fp || answer_fp)` detects WebRTC signaling MitM ✅ DONE
- **NS6** Chat `sender_id` enforced from authenticated session — prevents impersonation ✅ DONE
- **NS7** Node Ed25519 auth — node daemon authenticates to hub via `POST /v1/nodes/auth` (Ed25519 signed timestamp), no auth_key/password on node. JWT `scope: "node"` blocks group management (create/add/delete/join). Operator manages groups from browser only. ✅ DONE
- **NS8** GEK-required enforcement — node REFUSES connections when GEK is None (no `gek_required: false` bypass). GEK initialization via node local admin UI only. ✅ DONE

**Known remaining trust assumptions (Phase 12 — all actionable items done):**
- **T1** ✅ DONE: password split (auth_key / bundle_key, independent PBKDF2). Legacy migration on first login.
- **T2** Hub controls public key distribution → can substitute keys during invite. Fix: out-of-band key verification (safety numbers)
- **T3** SPA served by hub → fundamentally unsolvable in browser. Fix: native client or browser extension

**T3 attack surface reduction (2026-08-12, all phases complete):**
- **Phase 1** ✅ DONE: GEK bundles moved from hub to node P2P (WebRTC DataChannel). No hub fallback.
- **Phase 2** ✅ DONE: Keypair bundles moved from hub to node P2P. Registration stores locally, pushed to node on first connect. Hub never stores keypair bundles.
- **Phase 3** ✅ DONE: Hub GEK cleanup — `GET /gek` endpoint removed, `GEKBundle` model removed, `gek_bundles` table dropped, `keypair_bundle` column removed, member-add URL cleaned (`/gek` suffix removed), Alembic migrations updated.

**Browser crypto hardening (2026-08-13):**
- `_bundleKey` persisted in IndexedDB (CryptoKey survives page refresh)
- `_sessionKeys` persisted in sessionStorage (survives refresh, cleared on tab close)
- `_pkFromSk()`: derive X25519 public key from recovered private key via JWK export (no hub fetch)
- Removed auto-`regenerateKeys()` on login (was silently rotating hub keys, breaking GEK unwrap)
- Raw answer SDP saved before `setRemoteDescription` (Chrome strips sha-256 from multi-hash SDP)
- Upload chunk size: 48KB (fits aiortc SCTP limit after msgpack overhead)

**Architecture validated:** crypto primitives, GEK wrapping (ECIES), trust model,
key hierarchy, on-the-fly encryption, transport abstraction, DTLS channel binding.

## Second security review (2026-08-13) — see `second-review.md`

**6 critical, 7 high findings. Phase 11.5 is BLOCKING — see `devel-phases-next.md`.**
The current build must not host real private data.

The claims above about node sovereignty and P2P crypto material were **overstated**. The
GEK-HMAC proof, Ed25519 admin challenge and channel binding are real, but they are enforced
on the WebRTC path only, and three other paths into the node were left behind.

- **C1** Node HTTP API (`http_server.py`) serves private group **index and plaintext files
  with no authentication**, on `0.0.0.0`, for every group — bypasses the entire sovereignty layer
- **C2** `/v1/nodes/ws` trusts a client-supplied `node_id` → any user hijacks a node's
  signaling identity and impersonates it to browsers
- **C3** The node never authenticates itself to the client (`node_pk` is never verified, no proof of possession)
- **C4** Keypair bundles are served pre-proof and pushed to every node joined; PBKDF2-only → offline password attack
- **C5** Any member can overwrite arbitrary shared files (upload) and seize the group GEK (`gek_bundle_store` + auto-activation)
- **C6** GEK proof exists on WebRTC only — QUIC and TCP accept a bare JWT (chat injection)
- **H1** Multi-group nodes share one `chat_store` and one peer registry → cross-group chat leak
- **H2** Stored XSS in the node admin UI via uploaded filename → node takeover
- **H3** Hub is the key directory → key substitution at invite yields the GEK. "Unreadable
  even by the hub" is true against a *passive* hub only

**Corrections to remember:**
- `punch_nat()` is **not** a NAT traversal stack — one UDP probe, no STUN, no candidate
  gathering, one ISP validated. **ICE/STUN (WebRTC) is the traversal path**, for native
  clients too (via `aiortc` in Python)
- Argon2id 256 MB was applied to the **hub only**; `crypto.py` keystore is still 64 MB
- Sender keys must be distributed **pairwise to identity keys**, never GEK-derived
- Chat is plaintext on the wire and at rest; the index is plaintext on the WebRTC path

## Known calibration TODOs

- Argon2id `memory_cost`: ✅ DONE — bumped to 262144 (256 MB) in pw_version=2.
  Existing v1 users (64 MB) are transparently rehashed on next successful login.
  CLI `calibrate` command still TODO for per-hardware tuning.

## NAT traversal — empirical results

### QUIC native clients (demo-v2)

SFR residential Fedora 44 → meshbay.org OVH VPS:
- **NAT type**: Port-Restricted Cone
- **Mechanism**: `QuicChunkServer.punch_nat()` sends probe from QUIC server socket
- **Scripts**: `QE/demo-v2/`

### WebRTC browser clients (Phase 9 spike, 2026-08-10)

**SFR residential NAT** — Mobile 4G SFR → node behind SFR residential (Port-Restricted Cone + CGNAT 4G):

| Test | ICE path | Result |
|---|---|---|
| WiFi LAN | IPv6 direct | OK, ~100ms |
| 4G + IPv6 | IPv6 inter-network | OK, ~600ms |
| 4G + IPv4 only (IPv6 disabled) | STUN hole-punch IPv4 | OK, ~650ms |

**Orange Livebox NAT** — Firefox/Chrome laptop (SFR) → node behind Orange residential NAT:

| Test | ICE path | Result |
|---|---|---|
| Chrome laptop → Orange node | IPv6 inter-network | OK, ~7000ms |
| Firefox laptop → Orange node | IPv6 inter-network | OK, ~6700ms |
| Firefox laptop → Orange node (IPv6 disabled) | STUN hole-punch IPv4 | OK, ~6900ms |

- **Two ISPs validated** — SFR + Orange residential NAT, both work without TURN
- **No TURN relay needed** — ICE/STUN handles both NAT types automatically
- **Hub role**: signaling only (SDP/ICE relay via WebSocket, <1 KB)
- **Data path**: browser ↔ node P2P via WebRTC DataChannel
- **Scripts**: `QE/demo-v3/run_node_webrtc.py`, test page at `/webrtc-test.html`

## Key modules — où trouver quoi

| Need | Module | File |
|---|---|---|
| Chunk encryption (prod) | `meshbay_common.crypto` | `crypto.py` |
| Key derivation from password | `meshbay_common.keyderive` | `keyderive.py` |
| Key bundle (web) | `meshbay_common.keyderive` | `keyderive.py` + `static/keyderive.js` |
| GEK wrap/unwrap (ECIES) | `meshbay_common.crypto` | `crypto.py` |
| Double Ratchet (1:1 DM, future) | `meshbay_common.ratchet` | `ratchet.py` |
| Sender Keys (group chat) | `meshbay_common.senderkeys` | `senderkeys.py` (Phase 7.5) |
| AES-GCM (browser) | `meshbay_common.webcrypto` | `webcrypto.py` + `static/crypto.js` |
| Node keystore | `meshbay_node.keystore` | `keystore.py` |
| QUIC NAT punch (native) | `meshbay_node.transport.quic_server` | `QuicChunkServer.punch_nat()` |
| WebRTC transport (browser) | `meshbay_node.transport.webrtc_server` | Phase 9.3 — `aiortc` DataChannel |
| WebRTC signaling (hub) | `meshbay_hub.api.signaling` | Phase 9.2 — SDP/ICE relay |
| Browser transport client | `static/transport.js` | Phase 9.4 — WebRTC DataChannel |
| Web SPA | `static/app.js` | Phase 9.6 — Preact + preact-router |
| File download (large) | `static/app.js` | File System Access API (`showSaveFilePicker`) — stream to disk |
| i18n (browser) | `static/i18n.js` | `t()` lookup, ESM, localStorage lang selection |
| Admin API (hub) | `meshbay_hub.api.admin` | Phase 10.2 — user/group mgmt, audit logs, stats |
| Admin UI (browser) | `static/app.js` | Phase 10.3–10.4 — AdminPage component, 5 tabs |
| Auth dependencies | `meshbay_hub.api.deps` | `require_admin`, `require_moderator`, `get_current_user`, `require_user_scope` |
| Node auth (hub) | `meshbay_hub.api.nodes` | `POST /v1/nodes/auth` — Ed25519 challenge-response, node-scoped JWT |
| Site overlay | `site/` | Phase 10.1 — landing, about, downloads (meshbay.org-specific) |
| Notifications (hub) | `meshbay_hub.api.notifications` | Phase 10.5 — CRUD, per-user, triggered by admin/group actions |
| Version check (hub) | `meshbay_hub.api.hub` | Phase 10.10 — `GET /v1/hub/version` |
| Group self-service (hub) | `meshbay_hub.api.groups` | Phase 10b — create, join, members (GEK exchange is P2P) |
| File upload (node) | `meshbay_node.transport.webrtc_server` | Phase 10b.4 — FILE_UPLOAD MNP handler |
| GEK wrap AES (browser) | `static/crypto.js` | Phase 10b.2 — AES-256-GCM ECIES for WebCrypto |
| GEK HMAC proof (browser) | `static/crypto.js` | `hmacGEK()` — HMAC-SHA256 with DTLS channel binding |
| DTLS fp extraction (browser) | `static/transport.js` | `_extractDtlsFingerprint()` — SDP fingerprint for channel binding |
| DTLS fp extraction (node) | `meshbay_node.transport.webrtc_server` | `_extract_dtls_fingerprint()` — SDP fingerprint for channel binding |
| Ed25519 sign (browser) | `static/keyderive.js` | `signChallenge()` — admin challenge-response |
| Auth key derivation (browser) | `static/keyderive.js` | `deriveAuthKey()` — password split, hub never sees raw password |
| GEK wrap AES (Python) | `meshbay_common.crypto` | Phase 10b.2 — `wrap_gek_aes()` / `unwrap_gek_aes()` |
| IndexedDB cache (browser) | `static/app.js` | Phase 10b.5 — group index caching |
| Cross-group search (browser) | `static/app.js` | Phase 10b.6 — SearchPage, client-side |
| MSE video streaming (node) | `meshbay_node.transport.webrtc_server` | Phase 10c — ffmpeg fMP4 remux + encrypted segments |
| MSE video streaming (browser) | `static/app.js` | Phase 10c — MediaSource + SourceBuffer progressive playback |
| Video codec detection | `meshbay_node.transport.webrtc_server` | Phase 10c — `_probe_video()` ffprobe + MSE codec strings |
| Node daemon (production) | `meshbay_node.daemon` | Phase 11 — WebRTC + WS + chat + HTTP + audit all wired |
| Node config | `meshbay_node.config` | `node.toml` loader, `data_dir` for chat/audit DBs |
| Hub WS client | `meshbay_node.hub_client` | `login()` (Ed25519) + `maintain_ws()` + `send_ws()` — no auth_key on node |
| Chat store | `meshbay_node.chat.store` | SQLite per-group, `data_dir/{group_id}/chat.db` |
| Audit store | `meshbay_node.audit` | SQLite IP/action log, `data_dir/audit.db` (legal compliance) |
| Bundle store (node) | `meshbay_node.bundle_store` | SQLite P2P GEK + keypair bundles, `data_dir/bundles.db` — hub never stores crypto |
| P2P bundle exchange (MNP) | `meshbay_common.protocol` | GEK + keypair bundle STORE/FETCH/RESP message types |
| Bundle via DataChannel | `static/transport.js` | GEK + keypair bundle fetch during handshake, store after connect |
| Key persistence (browser) | `static/app.js` | `_bundleKey` in IndexedDB, `_sessionKeys` in sessionStorage |
| pkX from private key | `static/transport.js` | `_pkFromSk()` — JWK export to derive X25519 public key |
| Group delete (hub) | `meshbay_hub.api.groups` | `DELETE /v1/groups/{group_id}` — admin only |
| JWT scope enforcement | `meshbay_hub.api.deps` | `require_user_scope` — blocks node-scoped tokens from mutations |
| Node local admin UI | `meshbay_node.ui.app` | Dashboard, peers, groups, audit log (localhost:18000) |
| Demo scripts | — | `QE/demo-v1/*.py`, `QE/demo-v2/*.py`, `QE/demo-v3/*.py` (not versioned) |

## meshbay.org server (état cible)

- OS: Ubuntu 26.04 LTS, Python 3.14.4
- SSH: `ssh cbesson@meshbay.org`
- Caddy : reverse proxy HTTPS sur 80/443
- UFW rules: **22/tcp, 80/tcp, 443/tcp uniquement**
- Services légitimes : `meshbay-hub.service`, Caddy, PostgreSQL (local)
- Inventaire détaillé : `QE/server-state/meshbay.org.md`
- Deploy hub : voir `QE/server-state/meshbay.org.md`

## new rules, from now
Documents and demo/comments are written in english unless requested in french.