Openhaystack: Build 'AirTags' – track Bluetooth devices via Apple's network

Original Article ↗ Hacker News Discussion ↗

OpenHaystack is an open-source project that lets people turn generic Bluetooth hardware into Apple “Find My”–compatible trackers, effectively cloning many AirTag capabilities without Apple’s blessing. Commenters explore how closely these DIY tags can mimic official devices, where Apple could technically intervene, and how they compare to cheap third-party Find My accessories that use Apple’s official MFi program but often lack ultra‑wideband precision. The thread also probes broader implications for privacy, surveillance, and competing tracking networks from Google and Samsung, as well as niche uses like pet collars, mail sensors, and laptop tracking.

Project capabilities & Apple’s network

  • OpenHaystack lets you build custom Bluetooth beacons that piggyback on Apple’s Find My network.
  • Tags use BLE identities that are practically indistinguishable from Apple’s, including MAC rotation.
  • Apple could more easily block the method used to fetch encrypted location reports than block the BLE broadcasts themselves.
  • Original OpenHaystack relies on macOS Mail entitlements for access; other projects replicate access using just an Apple account and can run off Apple hardware.

Third‑party & clone trackers

  • Apple officially supports third‑party Find My devices via MFi / Find My programs; vendors need Apple‑issued keys for pairing.
  • Cheap “Find My”‑compatible tags and credit‑card‑style trackers are widely available from Chinese sellers; they pair directly in the Find My app.
  • These clones generally lack UWB precision finding and provide only a map pin + sound, but are much cheaper and easy to disassemble or repackage.
  • It’s unclear whether all very cheap tags use legitimate keys or have copied credentials from other approved devices.

Form factors & DIY hardware

  • Strong interest in non‑standard form factors: ultra‑thin wallet cards, pet‑friendly collars, integration into batteries, power banks, and other gadgets.
  • Most tag thickness comes from CR2032 holders, speakers, and buttons; these can be minimized or removed for one‑time setup devices.
  • nRF51/nRF52 chips work with the protocol; some implementations are written in Rust and run on microcontrollers or Linux.
  • Benefits of DIY vs $5 clones are debated; niche use‑cases include embedded tracking in laptops, equipment fleets, or custom devices.

Privacy, tracking abuse & protocol behavior

  • AirTags rotate keys to prevent long‑term tracking; projects can also pre‑allocate or derive many keys to evade “unknown tag nearby” alerts.
  • One project (FindYou) and other references show this can be used to circumvent anti‑stalking notifications.
  • Another demonstration used the Find My network for covert data exfiltration (e.g., hardware keyloggers) and for mailbox state sensing.
  • A user experiment (older) reported never receiving iOS alerts for an OpenHaystack‑based car tracker; current behavior is unclear.
  • Concerns raised about potential DoS by simulating massive numbers of BLE devices; Apple’s limits and device‑side buffering are unknown.

Competing networks & non‑Apple options

  • Some commenters want a robust non‑Apple equivalent; Google’s Find My Device network is criticized as slow, rate‑limited, and coverage‑poor due to aggressive privacy protections.
  • Opinions split: weaker network is comforting for privacy, but undermines theft/loss recovery.
  • Samsung’s tracking solution is reported as surprisingly strong, even in remote areas.
  • LoRaWAN, Amazon Sidewalk, and satellite‑IoT (e.g., Swarm) are mentioned as alternative small‑payload networks, but not equivalently open or ubiquitous.