The data that's synced when you log in is also encrypted, with a unique key derived from your Firefox Account called a scoped encryption key. Your key changes w

The data that's synced when you log in is also encrypted, with a unique key derived from your Firefox Account called a scoped encryption key. Your key changes when you change your password. We, (Mozilla) don't know your key (and don't want to know it). Disclosure, I implemented the sync feature of Send.