what is openhaystack fr?

OpenHaystack is a research project from TU Darmstadt's Secure Mobile Networking Lab that lets you build your own Bluetooth tracking tags and locate them through Apple's Find My network, the same infrastructure that powers Apple AirTags. All you need is a Mac and a small Bluetooth-capable device such as a BBC micro:bit. The way it works: you flash the provided firmware onto your Bluetooth device, which causes it to broadcast a signal in the background. Any nearby iPhone running iOS 13 or later will automatically pick up that signal, grab its own GPS location, encrypt it, and upload it to Apple's servers. You never see that step happening. Then, from the OpenHaystack app on your Mac, you download the encrypted location reports and decrypt them using a private key stored in your Mac's keychain. The result is a map showing where your tagged item was last seen, without needing any cellular connection in the tagged device itself. The project was born out of security research. The team reverse-engineered how Apple's offline finding system works, published a paper on it, and found two vulnerabilities in the process (one of which Apple subsequently patched). OpenHaystack is the public release of that research, packaged as a usable application. Installation involves a few steps that are more involved than a typical Mac app. The app requires a plugin for Apple Mail, which is how it authenticates with Apple's servers to retrieve location reports. Setup requires temporarily disabling macOS Gatekeeper to allow the Mail plugin to load. The project is experimental, incomplete, and explicitly not affiliated with or endorsed by Apple. The current firmware broadcasts a fixed public key, which means other nearby devices could in principle detect your tag. The README notes this may change in a future release. macOS 11 (Big Sur) or later is required.