Risks for losing encrypted data?

[casper]

This looks very cool, but what are the conditions where one could lose the ability to decrypt the encrypted data?

It would be nice if the docs could clarify this.

E.g: Is my SSH key involved in some way (I assume it is)? If so how? What if I lose or update my SSH keys, I assume the decryption will fail then? Specifically which SSH key is the system relying on (i.e. which SSH key is the one I need to find or restore, in case I lose my ability to decrypt for any reason)?