I'd like to sync my browsing data with multiple devices but I'm sure as hell I don't want to share my data with 3rd parties (whatever they claim). I've read in past that data saved via Firefox Sync are encrypted in a way that prevents Mozilla from decrypting it. I've read few articles about Firefox Sync but I'm still confused as to what prevents Mozilla from decrypting the data.
Now I'm using this same password to login to Firefox Sync in my browser. So the only secret for Sync is shared with Mozilla. If there was an additional secret on local PC, then loss of the PC would mean I wouldn't be able to decrypt my data, so the password must be the only secret.
So what actually prevents Mozilla from data mining on my private data?