When you back up into the Fog, all private files are ALWAYS encrypted. (It’s possible to back-up public files to other people’s Foggies, but privacy & security aren’t considerations with public files.)
The only way to decrypt your private files is with your encryption key. Your encryption key is never stored on the blockchain. It’s never stored on your Foggie Max. It’s up to you to maintain the security of your encryption key.
Back-ups the the Fog aren’t just secure — they’re completely private and anonymous as well.
For example, let’s say you buy 500GB on my Foggie Max, and I host your data for a year.
I’ll never know that I’m transacting with you (by name), and the data hosted on my Foggie Max is yours.
In addition, it will impossible for me to see/break into your files. They’ll always be fully encrypted.
Conversely, you’ll never know that you’re transacting with me (by name) on storing data on my Foggie Max.