Remember without reading back

In 2024, the first preview of Microsoft Recall taught the whole industry a lesson: encrypting a screen history isn’t enough if any program running as you can read it back. DejaVu was designed around that lesson. This post explains how, without hand-waving — and with the limits we think you should know.

Two jobs, two sets of keys

DejaVu does two different things, and they don’t get the same powers.

Remembering runs all day, in the background, without asking you anything. It needs to write your memory.

Looking back — searching, scrolling the timeline, opening a moment — happens when you ask for it. It needs to read your memory.

So the part that remembers is given only what it needs to encrypt: a public key. It can seal new moments, but it holds nothing that could open the past. Software spying on it would find no way to read your history.

The key in the chip

The key that can read your memory is never stored as a file you could copy. It is wrapped by a key that lives in your Mac’s Secure Enclave, the security chip built into Apple silicon. That key can’t be exported or copied to another computer, and using it requires you: Touch ID, or your password, depending on the level you choose.

Level	Who can open your memory
Standard	You, with Touch ID — or anyone who knows this Mac’s password
Strict	Only an enrolled Touch ID fingerprint
DejaVu code	Touch ID and a code specific to DejaVu

We say it plainly: at the Standard level, your Mac’s password opens your memory too. If someone else knows it, choose Strict or DejaVu code.

Short sessions

Once you open your memory, it doesn’t stay open. It locks again after a couple of minutes without activity, as soon as your screen locks or your Mac sleeps, and shortly after you close its windows. Touch ID from unlocking your Mac is never reused: opening your memory always asks again. When it locks, the keys are wiped from memory and cached pictures are dropped.

There is no back door around that: no local server, no programming interface, no URL scheme or shortcut that reads your memory without Touch ID.

A key per day — so deleting is real

On an SSD, deleting a file doesn’t guarantee it is gone: copies can survive in places you can’t reach. The only deletion you can trust is destroying the key.

So DejaVu gives every day its own key, and every 10-minute stretch of pictures its own key too. Text and the search index live in an encrypted database per day; pictures live in segments sealed frame by frame. When a day is deleted — by you, or because it is older than what you chose to keep — its key is destroyed first. The pictures, the text and the index become unreadable together, even in a copy made before.

Within a day, forgetting a moment also cleans the search index, so what you erased can’t be found by searching for it.

A folder macOS protects, out of your backups

Your memory lives in DejaVu’s own container, which macOS keeps other apps out of. That is a second barrier, not the first: encryption is. The folder is also excluded from Time Machine and from Spotlight, so neither an old backup nor a system search brings anything back.

Nothing to send, nothing sent

DejaVu has no account, no cloud and no analytics. It never uses the microphone or system sound, and never logs what you type. Your memories never leave your Mac.

What DejaVu can’t protect you from

We would rather say it than have you find out:

• If someone forces you to use your finger, they will see your memory. If that is a risk for you, keep less.
• Malware already running while you look back could see what is on your screen — as it could see your screen anyway.
• What you export is no longer protected by your Mac’s chip. Keep exports somewhere safe.
• An attacker in full control of macOS, with its protections turned off, can do anything.

If you want to see how other apps answer the same questions, our screen memory privacy checklist walks through them one by one.