First of all, if you have recently used your Threema ID on another device (i.e., if you have switched devices or if you have turned on a device that has been lying in storage), you can ignore this warning. To prevent it from (re)occurring when changing devices, it’s recommended to uninstall Threema on the previous device and then restart the current one.
If, however, you are certain that you’re not using your Threema ID on any other device, then your private key may be compromised. You should revoke your Threema ID and follow the steps listed below before creating a new ID.
- Ensure your device’s software is up to date
- If system updates are no longer available for your device, consider replacing the device with a current model
- Check your device for malware; when in doubt, reset the device
- Avoid “rooting” or “jailbreaking” your device
- Change passwords of important user accounts
- Lock your device and the Threema app with a passcode
- Don’t use easy-to-guess passwords (especially for Threema Safe), and never reuse the same password for different purposes. Use a password manager.
- Delete and reinstall the Threema app from an official source before creating a new ID. Please note that you will lose all Threema data (chat history, contact list, etc.), which is why you should export this data (in case you still need it) before reinstalling the app.
