ARIA
597a28050f
docs/09 §9.4 promised a SSH-host-key-style fingerprint confirm on first
pair, but the app built a default OkHttpClient with no certificate
handling — self-signed gateway certs were simply rejected.
Build the flow:
- TlsPinning.kt: PinningTrustManager wraps the platform default trust
manager; a rejected cert is accepted only when its SHA-256 fingerprint
matches the user-confirmed pin, anything else fails with
TlsFingerprintRequired (hostname verification still applies).
- SecureStore.pinnedCertFingerprint (Android EncryptedSharedPreferences +
desktop settings.json), cleared on forget().
- GatewayClient: pinning socket factory on the shared client (all legs
inherit it), new terminal State.TlsConfirmRequired, unwrap the nested
TlsFingerprintRequired in connect loop / watchdog / SSE / poll /
testHello.
- ConnectScreen: confirm dialog showing the fingerprint ("Confirm &
pin" re-runs the connect); IrisApp routes TlsConfirmRequired there;
ChatScreen + desktop tray handle the new state.
- Docs: §9.4 now describes the real flow (incl. SAN requirement), gap
table item 6 → implemented, setup.md limitation note updated.
- Tests: TlsPinningTest (fingerprint vs openssl, pin accept/reject,
live pin read, unwrap) + TlsPinningIntegrationTest (real TLS
handshake: unpinned → confirm data, pinned → 200).
Live E2E verified on the phone: first pair against a self-signed
IRIS_HTTP_CERT gateway shows the dialog, confirm pins, chat works,
auto-reconnect after gateway restart uses the pin.
174 lines
13 KiB
Markdown
174 lines
13 KiB
Markdown
# 09 — Pairing, Auth & Security
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## 9.1 Threat model
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- **Trusted domain:** a personal agent on the user's own machine; one owner, a
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few of their own devices (phone + desktop).
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- **Primary risks:** (a) an unauthorized device connecting to the WS and
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reading/driving the agent; (b) eavesdropping on the WS in transit; (c) token
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leakage in logs; (d) arbitrary file read via media pull.
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- **Not addressing (v1):** multi-tenant isolation, adversarial multi-user abuse,
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E2E encryption.
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## 9.2 Pairing flow
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1. **Generate a token.** `hermes gateway setup` (our `interactive_setup`) either
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uses an existing `IRIS_TOKEN` or generates a fresh high-entropy token
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(e.g. 32 bytes → 64 hex chars) and stores it in `.env`.
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2. **Present to the app.** Two options:
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- **QR code:** the setup prints a QR encoding
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`iris://pair?host=<lan-ip>&port=8791&secure=0&token=<token>` (or a WSS
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URL when `secure=1`). The phone scans it with the app's **Scan QR**
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button (or a system scanner → `iris://pair` deep link) → pre-fills
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settings.
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- **Manual:** user types the server URL + token in the app's Connect screen.
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3. **App connects.** First WS frame is `hello {token, device_id, device_name,
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caps, fcm_token?}`.
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4. **Server verifies.** Constant-time compare of `token` vs `IRIS_TOKEN`
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(`hmac.compare_digest`). Optionally check `device_id` against
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`IRIS_ALLOWED_USERS` (if set) or `IRIS_ALLOW_ALL_USERS`.
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5. **On success:** register the device in `devices.db`, **mint its
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per-device token** (if it has none yet) and return it in
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`hello.ack.device_token`. **On failure:** send `error {code:"auth"}`
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and close.
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`device_id` is a stable, app-generated UUID (persisted in the app's
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secure storage). It identifies the device for routing + push, **not** as a
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security principal (the token is).
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## 9.3 Auth model
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- **Two tokens, one principal per device.**
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- **Shared `IRIS_TOKEN` (bootstrap):** the setup token from
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`hermes gateway setup`. It authorizes *pairing* — a NEW device (no row
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in `devices.db` yet) presents it to connect, and the gateway mints a
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per-device token for it (returned in `hello.ack.device_token`). It
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keeps working for devices that never received a per-device token
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(legacy apps), so an upgrade never bricks a pairing.
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- **Per-device token (revocable):** minted once at pairing
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(`DeviceRegistry.issue_token`, 64 hex chars, stored in the `devices`
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table of `devices.db`). The app stores it in secure storage and
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presents it INSTEAD of the shared token from the next request on
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(`Authorization: Bearer <device-token>`). Both tokens are compared in
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constant time (`verify_token`); a revoked device is rejected before
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either comparison runs.
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- **Per-device revocation.** Two control surfaces (run on the gateway host):
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- **Setup flow** — `hermes gateway setup` → *Iris*: on an existing setup
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(devices already paired) it asks **"Remove a paired device?"** (default
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No). If yes: a numbered select menu (name, device id, last seen) whose
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LAST option is *Exit* (leaves the removal loop, continues the setup);
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picking a device asks for confirmation, then returns to the menu so
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several devices can be removed in a row.
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- **CLI** — `gateway-plugin/tools/iris_devices.py`:
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- `list` — paired devices (id, name, token minted?, last seen) + revoked ids.
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- `revoke <device_id>` — drops the device's row (token, push tokens,
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cursor) AND adds its id to the `revoked` denylist: the device can no
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longer connect with its device token **or** the shared token, while
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every other device is unaffected. This is the isolation primitive a
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shared token alone can't provide (a compromised device can't be cut
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off without rotating the token for everyone).
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- `unrevoke <device_id>` — removes it from the denylist so it can pair
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again (a fresh token is minted at the next pairing).
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- `reissue <device_id>` — rotates the device's token (the old one stops
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working; the app picks up the new one on its next (re)connect via
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`hello.ack`).
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Re-pairing a revoked device also works by giving the app a fresh
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`device_id` (e.g. `adb shell pm clear dev.iris.app`), which bootstraps
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with the shared token like any new device.
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- **Allowlist (optional):** `IRIS_ALLOWED_USERS` (comma-separated
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`device_id`s) restricts which *devices* may connect even with a valid
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token — useful if the shared token is exposed. `IRIS_ALLOW_ALL_USERS=true`
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disables the allowlist (dev only).
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- **Re-pairing / rotation.** Rotating `IRIS_TOKEN` no longer invalidates
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paired devices: they authenticate with their per-device tokens, which
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survive the rotation. Only bootstrap of NEW devices needs the new shared
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token. (Legacy devices without a per-device token still re-pair, as
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before.)
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## 9.4 Transport security
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- **Default (LAN/dev):** plain `ws://` on the trusted LAN. Fine for a home
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network.
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- **WSS (recommended for remote):** set `IRIS_WS_CERT` / `IRIS_WS_KEY`
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(self-signed or CA-signed). CA-signed certs work out of the box.
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For a **self-signed** cert the app shows its SHA-256 fingerprint on first
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pair (like a SSH host key); once the user confirms it, the fingerprint is
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pinned in secure storage (`SecureStore.pinnedCertFingerprint`) and the
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app's `PinningTrustManager` accepts exactly that certificate from then on
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(hostname verification still applies). A *changed* certificate fails
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again with a fresh confirm request — the user must re-confirm, like a
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changed SSH host key. No system trust-store install needed. Note: the cert
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must carry a **SAN** for the URL host (OkHttp's hostname verifier rejects
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CN-only certs even when pinned) — e.g. `openssl req -x509 ... -addext
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"subjectAltName=DNS:myhost,IP:192.168.1.10"`.
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- **Remote reachability options** (documented, user's choice):
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- **Tailscale / WireGuard** (recommended): gateway gets a stable tailnet IP;
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app connects over the private mesh. No public exposure.
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- **Reverse proxy / tunnel** (Caddy, Cloudflare Tunnel, ngrok): terminate TLS
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at the edge, forward WS to `127.0.0.1:8790`.
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- **Public bind** (`0.0.0.0`) + WSS + strong token — last resort.
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- **HTTP fallback leg (docs/19):** the gateway also serves the same frames
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over plain HTTP (`IRIS_HTTP_PORT`, default 8791) for the app's
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fallback transport. It is a *second door with the same lock*: the same
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Bearer token (constant-time `verify_token`) + the same device allowlist
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(`X-Iris-Device`), the same 64 KiB body cap and per-device rate limit as
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the WS. Optional TLS via `IRIS_HTTP_CERT` / `IRIS_HTTP_KEY`.
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`GET /v1/health` is unauthenticated by design (liveness only — it must
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not reflect tokens, device ids, or versions).
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- The app stores the server URL + (for self-signed) the pinned cert fingerprint
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in secure storage.
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## 9.5 Secret & PII handling
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- **Tokens/keys never logged.** Redact `IRIS_TOKEN`, FCM tokens/keys, ntfy
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tokens in all log output (hermes PII policy; `agent/redact.py` patterns).
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- **`device_id`** is a random UUID (not PII). `device_name` is user-chosen.
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- **Media pull** is gated by hermes `validate_media_delivery_path` + delivery
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root/recency/denied-path checks (`gateway/platforms/base.py:1684`) — the
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plugin can only serve files hermes is allowed to deliver (no arbitrary file
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read).
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- **Search** is local-only (user's own hermes home); no data leaves the machine.
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## 9.6 Profile safety
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- All plugin state lives under `get_hermes_home()/"iris"` (profile-aware).
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- Secrets are read with the scope-aware `_get_scoped_secret` pattern (see
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`plugins/platforms/irc/adapter.py:42`) so multiplexed profiles don't leak
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each other's tokens (fail-closed under `gateway.multiplex_profiles`).
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- The WS bind uses a scoped lock (`gateway.status.acquire_scoped_lock`) so two
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profiles can't bind the same port/identity.
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## 9.7 Hardening checklist
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- [ ] Constant-time token compare.
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- [ ] Bounded per-connection send buffer + rate limit on inbound frames.
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- [ ] Reject oversized frames / uploads (`max_upload_bytes`).
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- [ ] Verify media sha256 + re-sniff MIME (don't trust client).
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- [ ] Redact all secrets in logs.
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- [ ] WSS + cert pinning for remote.
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- [ ] Outbox retention cap + prune.
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- [ ] Fail-closed secret reads under multiplexing.
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## M7 verification (2026-08-20)
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Status of the §9.7 hardening checklist plus the related gaps found in the
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M7 research pass. "verified" = implemented and covered by
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`hermes-agent/tests/gateway/test_android.py` (35 tests) or the app build;
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"gap" = known limitation with the planned mitigation.
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| # | Item | Status | Evidence / mitigation |
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| --- | ------ | -------- | ----------------------- |
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| 1 | Constant-time token compare | verified | `gateway-plugin/pairing.py:34` (`hmac.compare_digest`); `test_wrong_token_rejected` |
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| 2 | Bounded per-connection send buffer + rate limit on inbound frames | verified | Send: `SEND_TIMEOUT_S` bounds every outbound send (`ws_server.py:47`, `broadcast`/`send_to`). Inbound: per-connection token bucket on JSON frames (20/s, burst 40) → `error {code:"rate_limited"}` + close on exceed (`ws_server.py:55`, `_TokenBucket`, `_on_frame`); binary upload chunks exempt (see gap 1) |
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| 3 | Reject oversized frames / uploads (`max_upload_bytes`) | verified | `serve(max_size=adapter.max_upload_bytes)` (`ws_server.py:139`); per-upload total cap in `media.py` (`create_upload`/`feed`); `test_upload_declared_over_limit_rejected`, `test_upload_midstream_over_limit_rejected` |
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| 4 | Verify media sha256 + re-sniff MIME (don't trust client) | verified | `media.py:317` (`complete_upload` digest check), `media.py:147` (`reclassify_kind`); `test_upload_sha256_mismatch_rejected`, `test_reclassify_kind_does_not_trust_client` |
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| 5 | Redact all secrets in logs | gap | No mechanical redaction; the token is printed to stdout by design during `hermes gateway setup` (`gateway-plugin/adapter.py:632,650`). Mitigation: stdout is operator-only, not a log file; a redaction pass over gateway logs is planned |
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| 6 | WSS + cert pinning for remote | implemented | WSS supported server-side (`IRIS_WS_CERT`/`IRIS_WS_KEY`, `ws_server.py:122`); the app pins self-signed certs via a fingerprint-confirm flow: `PinningTrustManager` wraps the platform default trust manager, a rejected cert is accepted only when its SHA-256 fingerprint matches the user-confirmed pin in `SecureStore.pinnedCertFingerprint`, anything else fails with `TlsFingerprintRequired` → confirm dialog on the Connect screen (`app/shared/src/commonMain/kotlin/iris/net/TlsPinning.kt`, `GatewayClient.State.TlsConfirmRequired`); hostname verification still applies (the cert needs a SAN for the URL host). CA-signed certs work out of the box; LAN `ws://` stays the default. Tests: `TlsPinningTest`, `TlsPinningIntegrationTest` |
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| 7 | Outbox retention cap + prune | verified | `gateway-plugin/outbox.py:48` (`retention_hours` default 72h, `max_rows` cap, `take_overflow_pruned`); `test_outbox_row_cap_prunes_oldest` |
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| 8 | Fail-closed secret reads under multiplexing | verified | `_get_scoped_secret` (`gateway-plugin/adapter.py:74`) for `IRIS_TOKEN`/`IRIS_WS_CERT`/`IRIS_WS_KEY`/FCM/ntfy secrets; scoped bind lock in `connect()` (`adapter.py:779`) |
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| 9 | Gap: inbound frame rate limiting | implemented | Closes item 2: token bucket in `ws_server.py` (JSON frames only). Binary upload chunks are exempt — a 100 MB upload is 400 × 256 KiB frames in a tight loop and would exhaust any sane bucket; uploads are already bounded by per-frame `max_size` + the per-upload total cap |
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| 10 | Gap: Android token storage | implemented | `AndroidSecureStore` → `EncryptedSharedPreferences` (MasterKey AES256_GCM) with one-time migration of the plain `iris` prefs (read old key → write encrypted → delete old key); dep in `app/shared/build.gradle.kts` (`app/shared/src/androidMain/kotlin/iris/platform/AndroidSecureStore.kt`) |
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| 11 | Gap: guard not committed | implemented | `.pre-commit-config.yaml` (local hook → `scripts/guard_hermes_agent.sh --staged`); a fresh clone gets the guard after `pre-commit install` |
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| 12 | Gap: in-app QR scanner | implemented | `hermes gateway setup` renders a terminal QR (`gateway-plugin/qr.py`, pure-stdlib encoder) and the app's Connect screen has a **Scan QR** button (CameraX + ML Kit, `QrScanActivity`) plus an `iris://pair` deep link (`PairLink.parse`); `docs/20` |
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| 13 | Gap: per-device tokens (revocation) | implemented | `DeviceRegistry.issue_token` mints a 64-hex per-device token at pairing (stored in `devices.db`, returned in `hello.ack.device_token`); the app stores it in secure storage and presents it instead of the shared `IRIS_TOKEN` (bootstrap path unchanged). `tools/iris_devices.py revoke <device_id>` drops the device + denylists its id (rejected even with the shared token); `unrevoke`/`reissue` for re-pairing/rotation. `docs/09` §9.3 |
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