Covid Bracelet, compatibile with Covid Apps on iOS and Android
- Sends and receives exposure beacons as specified by Google and Apple for Covid Contact Tracing
- Rolling, encrypted, anonymous beacons
- Compatible with Apple iOS and Android phones
- With rolling proximity identifiers and encrypted metadata
- Proximity identifiers and BLE addresses change every 10 minutes
- Stores own keys for 14 days
- Stores contacts of more than 5 minute duration
- Upon infection upload keys to a public database
- Retrieve keys of infections from database
- computes rolling proximity identifiers
- compares to stored contacts to check for exposure
Builds on on Zephyr OS and NRF52 BLE SOCs. Note: as we for now do not use the flash for key storage, this currently only works on nrf52480 or you can just store a very small number of keys. Moving the keys to flash is on the TODO list and will fix this.
We use Zepyhr master as we need a newer mbed TLS as the ones that ships with Zephyr 2.2. We are waiting for the Zepyhr 2.3 release. To build, please install Zephyr and compile via west. Note that Platform.io does not support Zephyr 2.3 rc / Zepyhr master at the current time.
Note: this is a proof of concept and not ready for production
Open / Possible next steps
- firmware of the air updates (signed): done in testing
- fix entropy: keys are always the same on boot up
- time sync
- set device name, user id or so in Flash
- set scanning interval to the correct value, for now we just use the default
- set advertisement interval, correct value, for now we just use the default: should be 200-270 milliseconds
- store long-term contacts in flash
- set transmit power and store this in the corona beacons
- get infections from DB, check their signatures
- extensive logging: crash, reboot, battery level, charging state, contacts, memory useage, flash usage,
- extensive compatibility testing with Apple iOS and Android devices
- contininous integration testing
- Energy efficiency
- BLE advertisements sets
- Secure GATT services and authentication of base statation in general
- More platforms: with display etc.
Possible platforms for real-world deployment many, as many of the cheap fitness trackers base on NRF52 or chips with similar capabilities.
However, many would need the firmware to be shipped to manufactures.
- Watch UI
- Pine Time could be good for testing
TODOs App and Basestation
- extend this beyond the simple basestation
- read keys form national databases