Adds a layered entropy mixer for first-boot identity Ed25519 keygen,
primarily to address ESP32 where the hardware TRNG (WDEV_RND_REG) is
only fed real entropy once the internal WiFi/BT radio is enabled —
but identity gen runs before that on companion and indefinitely
before that on a bare repeater. ESP-IDF's bootloader_random_enable()
is not compiled by Zephyr-Espressif HAL, ruling out that workaround.
Design reviewed with nextgens (author of upstream meshcore-dev/
MeshCore#2280 which fixes the same issue via BT/WiFi init/pull/deinit).
ZephyrRNG::random — retry sys_csrand_get up to 4x with k_msleep
backoff; cold-reboot on persistent failure. Previously fell back
silently to sys_rand_get (xoshiro PRNG), which would have produced
a weak Ed25519 seed on CSPRNG error. BUILD_ASSERT enforces
CONFIG_CSPRNG_ENABLED.
ZephyrRNG::mixIdentitySeed — layered entropy mixer for one-shot
identity keygen. Combines sys_csrand_get (early + late),
HWINFO unique device ID, caller-supplied ADC LSB noise, 200ms of
CPU cycle-counter jitter (NIST SP 800-90B class source), and
50ms more jitter in an independent timing window. Conditioned via
AES-256-CTR (NIST SP 800-108 KDF-in-Counter-Mode): SHA-256 of the
pool extracts a 32-byte AES key; AES-256-ECB on an incrementing
128-bit counter expands to the requested output length. Uses PSA
crypto already enabled in zephcore_common.conf. NIST-style
repetition-count + variance health check on jitter samples;
reboot on degenerate output. ~280ms one-time cost at first boot.
LoRa radio TRNG was considered as an additional source but rejected
on expert advice — radio sources are attacker-influenceable
(jamming/spoofing).
ui-joystick BLE passkey — switch from sys_rand32_get (non-crypto
xoshiro) to sys_csrand_get. The 6-digit passkey is the MITM
protection the rest of the BLE config enforces; predictable PINs
weaken it.
Identity reserved-prefix loop — replace the silent 10-attempt cap
(which committed whatever it had on fall-through) with a
bounded-retry-then-reboot pattern.
Also: fix a pre-existing scope bug at main_companion.cpp:357 in
the MESH_EVENT_PREFS_DIRTY handler — data_store was referenced
inside mesh_event_loop() but declared 50+ lines later. Moved the
call into a forward-declared helper defined after the statics.
Unrelated to crypto work but uncovered during build verification;
every companion build was broken.
prefs.path_hash_mode already exists end-to-end (NodePrefs field,
ZephyrDataStore persists it, CompanionMesh::sendFlood reads it as
the path_hash_size for every outbound flood, and the phone protocol
exposes it). Add a joystick UI control so it can be set locally
without going through the phone app.
System → Device gets a new "Path hash: Nb" item; ENTER cycles
1 → 2 → 3 → 1 (path_hash_mode 0 → 1 → 2 → 0). Save goes through
the existing mesh_save_* deferred-write infrastructure
(UI_ACTION_PATH_HASH_MODE_SAVE, pending_path_hash_mode atomic),
handled in the mesh thread with savePrefs().
-open the screen with no fix → "Lat | Lon" placeholder;
first fix arrives → lat/lon for 4 s → altitude for 4 s → repeat;
lose fix → state resets, next fix starts fresh on lat/lon.
UIScreen gains onDisplayOff()/onDisplayOn() hooks. JoystickUITask tracks
display state and dispatches them on transition — at top of loop()
(catches display.c's auto-off, which fires behind our back) and right
after _display.turnOn() in the wake path (immediate resume).
Override in SnakeScreen and GPSSettingsScreen: stop their periodic
k_timers while the screen is off, restart on wake. Game state and
GPS-fix state are preserved across sleep. Snake doesn't crash into a
wall five seconds after the screen sleeps anymore.
Other screen timers (Countdown alarm, Contacts/Admin response timeout,
the global lock timer) intentionally keep running — their job is to
fire while the user is idle.
Also: wake-from-off now reschedules the lock timer if not already
locked, so a keypress near the end of the lock window gives you a
fresh LOCK_AFTER_MS instead of being immediately re-locked.
UIScreen gains onEnter()/onExit() lifecycle hooks; poll() and the
_curr->poll() call in the main loop are removed. Each screen with
periodic or deadline-based work owns its own k_timer:
- one-shot timers: Splash dismiss, Countdown alarm, Contacts ping
timeout, RepeaterAdmin cmd/login timeout, Unread preview expiry
- periodic timers: Snake tick, GPSSettings sample
- onEnter()-only: Repeaters discover, Doom start
- deleted: Home, Stopwatch (were empty)
Timer ISR callbacks only signal _task->notify() — never mutate
screen state. Main-thread render() handles transitions. Setting
_curr now fires onExit on the outgoing screen and onEnter on the
incoming one, so timers are scoped to screen lifetime and can't
fire stale events on the wrong screen.
liquidraver