Your days are yours. Not ours.
Emi encrypts each day on your phone, with a key that stays on your phone. The code is public, so you can check this page against it.
What happens to one day.
You log a day.
Period, symptoms, mood, sex or a note.
Your phone seals it.
Emi encrypts the day before it writes it. The key is in your iPhone keychain.
In the app todayOnly the result leaves.
With sync, the server keeps ciphertext, a revision number and a write time. It holds no key.
Designed, not built yetWho holds the keys. Not Emi.
Your phone
The vault key encrypts every day. It never leaves the phone.
You
A recovery code of 26 characters, shown once. Keep it away from the phone.
Emi
No key. So no request to Emi, or to Amazon Web Services, can return one of your days.
What Emi does not defend against.
Four limits, stated here and not hidden. Each one says what you can do.
A lost phone and a lost code
The days are gone. An Emi that could recover them could read them.
A phone somebody can unlock
They can read the screen. Keep the app lock on. It is on by default.
A phone running something hostile
No app can defend itself from under the system. Keep iOS current.
What the outside learns
With sync, the server learns how many records you keep, and when each one was written.