The Smart Key is always held by the user and is protected by a backup key that can be written down and stored as a paper wallet. Feel free to print and use the attached PDF document for this. 

Aside from your paper copy, your Smart Key is stored in the cryptographic section of your phone and protected by: your phone's lock-screen pin; your Universal Wallet pin; and bio-metric data (optional). Your SmartKey will never touch the internet and is not stored by Ethos.