Kara Zajac
ad81964398
Build APK / build (push) Waiting to run
- detect/PresenceEngine.kt: identity-agnostic streaming detector for key-rotating clones (novel-churn gate, seamless-handover chain, co-movement gate, coherence). Full design in docs/detection-rotation-clone.md. - Wired into ScanService as a parallel signal; CONFIRMED verdict raises a distinct rotating-tracker alert (softer tiers stay silent pending real-capture validation). - PresenceEngineTest: synthetic clone (moving -> CONFIRMED), stationary clone (gated), single real tracker + far-ambient (CLEAR). - CI now runs :app:testDebugUnitTest so the engine has behavioural verification, not just a compile check. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0187UiEtasyowhEBYs6s9iF5
146 lines
7.1 KiB
Markdown
146 lines
7.1 KiB
Markdown
# VIGIL
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**What's been following you?**
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A native Android (Kotlin) app that watches for personal item-trackers — Apple
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AirTags, Tile, Samsung Galaxy SmartTags, and Google Find My Device / DULT tags —
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that are **travelling with you over time**. It is the temporal counterpart to
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[OVERWATCH](https://github.com/KaraZajac/OVERWATCH):
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> **OVERWATCH is spatial** — *what surveillance is watching this place, right now.*
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> **VIGIL is temporal** — *what has been with me, across time and places.*
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A tracker being *near* you means nothing — trackers are everywhere. The signal is
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**persistence**: the same device seen at many of *your* distinct locations, over a
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sustained window, while close enough to actually be on you. VIGIL is built around
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that idea.
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> ⚠️ **Prototype / work in progress.** The scanning, parsing, temporal store,
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> co-movement engine, allowlist, and learned baseline are in place; the app builds
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> in CI. Wire-format offsets and thresholds are from the research brief and need
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> validation against real hardware (see [Status](#status)).
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---
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## Privacy first — like OVERWATCH
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VIGIL requests **no `INTERNET` permission at all.** There is no server, no account,
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no telemetry. Every tracker, every sighting, and the entire learned baseline live
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in an on-device SQLite database and never leave the phone. It listens only — it
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never transmits, probes, or interferes with any device.
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---
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## What it detects
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Four native BLE wire formats today, plus the emerging unified DULT format. VIGIL
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recognises each ecosystem and, where the ecosystem signals it, filters to the
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**separated-from-owner** state — the only state in which a following tracker is
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detectable (see the research brief).
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| Ecosystem | BLE signature | Separated-state signal | Passive re-link window |
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|---|---|---|---|
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| **Apple Find My / AirTag** | mfg data, company `0x004C`, type `0x12` | status byte "maintained" bit cleared | ~24 h (key static per day) |
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| **Google Find My Device** | service data `0xFEAA`, frame `0x40`/`0x41` | frame `0x41` = separated (cleartext) | ~24 h once separated |
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| **Samsung Galaxy SmartTag** | service data `0xFD5A` | state byte (lost / overmature-lost) | ~24 h once overmature |
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| **Tile** | service data `0xFEED` / `0xFEEC` | none — static MAC, always findable | indefinite (static MAC) |
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| **DULT (unified, emerging)** | service data `0xFCB2` | near-owner bit (byte 14 LSB) | ~24 h separated |
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Chipolo, Pebblebee, eufy, Motorola, etc. inherit the signature of whichever
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network (Apple or Google) their SKU joined — VIGIL detects the **network**.
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## How it decides
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Each parsed sighting is geotagged with a coarse fix and written to the temporal
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store. A tracker is escalated `OBSERVED → SUSPICIOUS → ALERTING` only when it
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clears the **co-movement test**:
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- **≥ 3 sightings** (debounced to one per 15 min), across
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- **≥ N distinct places** (geohash-7 cells; N = 2/3/4 by sensitivity), over
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- **≥ T minutes** (30/45/90 by sensitivity), **and**
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- an **RSSI proximity gate** — it must have been genuinely close (on-body/in-bag)
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at least once. This is the piece AirGuard omits, and it rejects "a Tile in a
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passing car."
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Two trust signals suppress false alarms:
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- **Allowlist ("This is mine").** Tap a tracker to mark it approved — your own
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AirTag, your partner's Tile — and it never alerts again.
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- **Learned offline baseline.** VIGIL learns the places you dwell (home, work) as
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*anchors*, and a tracker seen at an anchor across several distinct days is
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auto-marked **Known (home)**. So the household tags that are always around you
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fall silent on their own, entirely on-device.
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## The hard part — catching clones (problem #1)
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Every shipping detector (AirGuard, iOS, Android's built-in) keys on **device
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identity**. A key-rotating clone (e.g. Positive Security's *Find You*: ~2,000
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Find My keys, a new one every 30 s) looks like 2,000 one-off devices and evades
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all of them — it tracked a phone for 5 days with zero alerts.
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VIGIL's headline goal is to detect the **attack, not the device**: a rotating
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clone is one physical radio holding an unbroken, close-range, co-moving RF
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*presence* even as its identity churns thousands of times faster than any
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standards-compliant tracker is allowed to. The full algorithm — a CUSUM churn
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trigger, an identity-agnostic presence-track confirmer, and a co-movement gate,
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plus the "identity-path × churn-path squeeze" that leaves no safe rotation rate —
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is designed in **[docs/detection-rotation-clone.md](docs/detection-rotation-clone.md)**.
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It's now implemented as a first version in `detect/PresenceEngine.kt` (unit-tested
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against synthetic clone/ambient traces) and wired into the scan service to raise a
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distinct rotating-tracker alert; field-tuning against real captures is what remains.
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## Architecture
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VIGIL reuses OVERWATCH's proven scanning stack and diverges where the temporal
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mission demands it (a persistent database instead of an in-memory store).
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```
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scan/TrackerSignatures.kt BLE hex signatures for every ecosystem
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scan/TrackerParser.kt ScanResult -> TrackerObservation (four wire formats)
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scan/BleTrackerScanner.kt filtered BLE scan (screen-off capable) -> observations
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service/ScanService.kt foreground service; geotags + persists + alerts
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data/db/VigilDatabase.kt Room: trackers, sightings (14-day), baseline places
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data/TrackerRepository.kt ingest + baseline + evaluate on every sighting
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detect/CoMovementEvaluator the temporal co-movement test + RSSI proximity gate
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detect/BaselineManager.kt learns anchor places -> auto-trusts household tags
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data/location/LocationProvider.kt fused location (ported from OVERWATCH)
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ui/ + MainActivity.kt Compose UI (Catppuccin Mocha)
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```
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## Paper
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A full technical write-up — the per-ecosystem detection methodology (how VIGIL
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tracks each tracker type) and the harder modeling engine for what AirGuard and the
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built-in detectors miss — is in **[paper/vigil.md](paper/vigil.md)**.
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## Build
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Standard Android/Gradle. A committed debug keystore signs CI and local builds
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identically.
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```bash
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./gradlew :app:assembleDebug
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# APK -> app/build/outputs/apk/debug/app-debug.apk
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```
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CI (`.github/workflows/build.yml`) builds a debug APK on every push and attaches
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an APK to a GitHub Release on `v*` tags.
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## Status
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Prototype. In place: BLE scan + filters, per-ecosystem parsing, Room temporal
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store, co-movement evaluator with RSSI gate, allowlist, learned baseline, the
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rotation-clone presence engine (v1, unit-tested), foreground service, Compose UI.
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**Not yet:** field-tuning the clone engine on real captures, GATT play-sound /
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DULT get-identifier, and empirical validation. Before trusting the parser, capture real devices with nRF Connect —
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the SmartTag2 offsets are inferred from gen-1, and the Tile/AirTag reversing is a
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couple of years old.
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## Credits & prior art
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Stands on the shoulders of **[AirGuard](https://github.com/seemoo-lab/AirGuard)**
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(TU Darmstadt / Seemoo-lab) and the SEEMOO Find My research, the IETF **DULT**
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working group, Adam Catley's AirTag teardown, and Positive Security's *Find You*
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clone research. VIGIL's aim is to go *beyond* AirGuard on the attacks it
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structurally cannot catch — see the design doc.
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