k_card/Setup.md

# Setup

Last updated: 2026-04-24

This is a living setup/status file for the local ChromeCard workspace at `/home/user/chromecard`.
Update this file whenever environment status or verified behavior changes.

## Repository Policy

- Treat `/home/user/chromecard/CR_SDK_CK-main` as read-only in this workflow.
- Do not add or modify helper/test scripts inside `CR_SDK_CK-main`.
- Keep host-side helper scripts at workspace root (`/home/user/chromecard`).

## Documentation Maintenance

- Canonical living status docs for this workspace are:
  - `/home/user/chromecard/Setup.md`
  - `/home/user/chromecard/Workplan.md`
- After each meaningful execution step, update at least:
  - `Setup.md` for observed environment/runtime state
  - `Workplan.md` for phase progress and next blocking action
- Keep helper script paths consistent in docs:
  - `/home/user/chromecard/fido2_probe.py`
  - `/home/user/chromecard/webauthn_local_demo.py`
- Treat `CR_SDK_CK-main/README_HOST.md` as historical reference unless its script paths are aligned with this workspace policy.

## Scope

- Experimental ChromeCard connected over USB.
- Firmware source tree: `/home/user/chromecard/CR_SDK_CK-main`.
- Host-side FIDO2 demo tools:
  - `/home/user/chromecard/fido2_probe.py`
  - `/home/user/chromecard/webauthn_local_demo.py`
- Target runtime platform: Qubes OS with 3 AppVMs:
  - `k_client` (browser + enrollment process)
  - `k_proxy` (card-connected proxy/auth client)
  - `k_server` (protected resource/backend)

## Planned Transport Evolution

- Current phase assumption: card is connected directly to `k_proxy` (USB).
- Future target: card is connected to a phone, and `k_proxy` performs validation through a wireless link to that phone.
- Design implication: keep authenticator transport behind an abstraction in `k_proxy` so USB-direct and phone-wireless backends can be swapped without changing client/server API contracts.

## Target Qubes Topology

- Base template for all AppVMs: `debian-13-xfce`.
- Allowed network paths:
  - `k_client` -> `k_proxy` over TLS
  - `k_proxy` -> `k_server` over TLS
  - Response traffic returns on those established connections.
- Disallowed direct path:
  - `k_client` -> `k_server` (direct access should be blocked).

Functional roles:
- `k_client`:
  - Browser-only traffic client.
  - Runs a user enrollment process.
- `k_proxy`:
  - Current: connected to the ChromeCard over USB.
  - Future: connects wirelessly to phone-attached card for validation.
  - Accepts TLS requests from `k_client`.
  - Uses card-backed FIDO2/WebAuthn operations to authenticate user/session.
  - Calls `k_server` over TLS after successful authorization.
  - Returns proxied data and session information to `k_client`.
- `k_server`:
  - Hosts resource(s) requiring login via the proxy-mediated flow.
  - Provides a dummy protected resource for early integration testing (monotonic increasing number/counter).
  - May hold user/session state logic needed for authorization decisions.

UI baseline for each AppVM (start-menu visible apps):
- Firefox
- XFCE Terminal
- File Manager

## Target Request Flow

1. `k_client` sends HTTPS request to `k_proxy`.
2. `k_proxy` validates/authenticates user via card-backed flow.
3. If allowed, `k_proxy` opens HTTPS request to `k_server` resource.
4. `k_server` responds to `k_proxy`.
5. `k_proxy` returns response payload to `k_client` plus session state.
6. Subsequent requests reuse session state so card auth is not required every request.

Implementation note:
- `k_proxy` does not need a full web server stack; a minimal TLS API service is sufficient.
- Session state should be integrity-protected (signed/encrypted token or server-side session ID) with TTL and revocation behavior defined.
- `k_proxy` and `k_server` must be safe under concurrent access (thread-safe state handling).

## Minimum Service Behavior (Current Target)

- `k_server`:
  - Expose protected endpoint returning an increasing integer value (dummy resource).
  - Increment behavior must remain correct under concurrent requests.
  - Optionally expose/maintain user/session validation logic.
- `k_proxy`:
  - Accept concurrent HTTPS requests from one or more `k_client` instances.
  - Perform card-backed auth when no valid session is present.
  - Cache and validate session state so repeated requests avoid card access until expiry.
  - Forward authorized requests to `k_server` and return upstream data plus session info.

Thread-safety expectation:
- Shared mutable state (counter, session store, user state) must be protected against races.
- Parallel requests must not corrupt session records or return duplicate/skipped counter values caused by unsafe updates.

## Test Topology Requirement

- Support concurrency testing from multiple simultaneous clients:
  - multiple browser tabs/processes in one `k_client`, and/or
  - multiple `k_client` AppVM instances if available.
- Validate both correctness and stability under load:
  - session reuse works as intended
  - unauthorized access stays blocked
  - protected counter/resource remains consistent.

## Current Status Snapshot (2026-04-24)

- Python is available: `Python 3.13.12`.
- `python3 fido2_probe.py --list` runs, but returns: `No CTAP HID devices found.`
- No HID raw device nodes currently visible: `no hidraw devices visible`.
- `west` is not currently installed/in PATH: `west not found`.
- The checked-out `CR_SDK_CK-main` tree appears incomplete for documented sysbuild role layout:
  - missing: `mvp`, `setup`, `components`, `samples`
- `CR_SDK_CK-main/scripts/build_flash_mvp.sh` exists, but it expects the above role directories.
- Python helper scripts were intentionally moved out of `CR_SDK_CK-main/scripts` and are now maintained at workspace root.
- Qubes VM provisioning is currently blocked: `libxenlight` failed to create domain `k_client`.

Implication:
- We cannot currently confirm live FIDO2 connectivity from this host.
- We cannot currently run the documented firmware build/flash flow.

Session note (2026-04-24):
- Markdown tracking was reviewed and normalized around `Setup.md` + `Workplan.md` as the active, continuously updated execution record.
- AppVM template decision recorded: use `debian-13-xfce` for `k_client`, `k_proxy`, and `k_server`.
- VM start attempt failed with Xen toolstack error: `libxenlight have failed to create new domain 'k_client'`.

## Known FIDO2 Transport Boundary

- FIDO2 on this firmware is handled via USB HID (CTAPHID), not Wi-Fi/BLE/MQTT.
- Key code points in `CR_SDK_CK-main`:
  - `mgr_fido2.c`: `mgr_fido2_init()` registers `fido2_ctaphid_handle_packet`.
  - `ctaphid.c`: `fido2_ctaphid_handle_packet(...)`.
  - `cr_config.h`: FIDO2 HID report descriptor definitions.

## Host Bring-Up Steps (How To Get To A Working FIDO2 Check)

1. Confirm USB enumeration and HID visibility.
- Replug card with a known data-capable cable.
- Check: `ls -l /dev/hidraw*`

2. If needed, grant Linux HID access for this device.
- Add rule at `/etc/udev/rules.d/70-chromecard-fido.rules`:
```udev
SUBSYSTEM=="hidraw", ATTRS{idVendor}=="1209", ATTRS{idProduct}=="0005", MODE="0660", TAG+="uaccess"
```
- Reload/apply rules and replug the device.

3. Verify CTAP HID presence.
- `python3 /home/user/chromecard/fido2_probe.py --list`
- Then:
- `python3 /home/user/chromecard/fido2_probe.py --json`

4. Run local WebAuthn bring-up demo.
- `python3 /home/user/chromecard/webauthn_local_demo.py`
- Open `http://localhost:8765` (use `localhost`, not `127.0.0.1`).

5. Execute register/login test.
- Register a user.
- Login with the same user.
- Confirm no origin/challenge mismatch errors.

## Build/Flash Prerequisites (How To Get To Firmware Build)

1. Ensure full SDK checkout layout exists under `CR_SDK_CK-main`:
- `mvp`
- `setup`
- `components`
- `samples`

2. Ensure toolchain is available in shell:
- `west --version`
- `nrfjprog --version`

3. Once layout/tooling are in place, run:
- `cd /home/user/chromecard/CR_SDK_CK-main`
- `./scripts/build_flash_mvp.sh`

## Open Gaps To Resolve

- Why Xen/libxenlight cannot create the `k_client` domain on this host (memory/pool, stale domain, template, storage, or hypervisor state).
- Why no `/dev/hidraw*` device is visible despite USB connection.
- Whether udev rule is missing or device VID/PID differs from expected.
- Whether current firmware on card exposes the FIDO2 HID interface.
- Whether a full `CR_SDK_CK-main` checkout (with role directories) is available locally.
- Whether server-side code should be pulled now for broader CIP/WebAuthn integration testing.
- Exact Qubes firewall and service binding rules to enforce the `k_client -> k_proxy -> k_server` chain.
- Exact enrollment process interface running in `k_client` and how it reaches `k_proxy`.
- Concrete session format/lifetime so cached sessions reduce card prompts without weakening security.
- Precise ownership split of session/user state between `k_proxy` and `k_server`.
- Concrete concurrency limits and acceptance criteria (requests/sec, parallel clients, latency/error thresholds).