End-to-end encryption for synced captures

End-to-end encryption is included with Pro. With it, capture files are encrypted on your Mac before they upload, and the server stores only the encrypted copies.

Free and Individual sync is protected in transit and encrypted at rest by the storage provider, but it is not end-to-end encrypted. Compare the options on Security and Pricing.

How it works

• A key for each item. Every synced item gets its own random 256-bit key. The file and its thumbnail are encrypted with that key using AES-256-GCM before upload.
• Your identity key. Your account has its own key pair. The private key is stored in the macOS Keychain on your Mac. It is not uploaded in readable form.
• Wrapped keys. Each item’s key is locked (“wrapped”) with your public key, so your other devices can open the item once they have your private key. When you share a folder, each member gets a copy of the item key wrapped for them.

The server stores the encrypted files and the wrapped keys, but not a private key that can open them.

What is and isn’t encrypted

Encryption covers the contents of capture files. The server still needs some information to sync and search your library, and that information stays readable to it.

Encrypted before upload	Readable by the server
The image, video, audio or document file	File name and title
Its thumbnail	Page URL and extracted article text
	OCR text, transcripts and annotation text
	Tags, and folder and collection names
	Dimensions, file size and timestamps
	Your email address and device details

Files in your save folder on your Mac are ordinary files. This feature protects the copies uploaded to the cloud. It doesn’t encrypt your local library.

Set your recovery password

The first time you sign in with encryption on, SuperCapture shows Set a Password. This recovery password lets you unlock your captures on another device.

1. Enter a recovery password and confirm it.
2. Click Set password.

The server stores a backup of your private key that is locked with this password. The service can’t use the backup without the password.

When you sign in on another Mac, it shows Unlock your screenshots. Enter the same recovery password and click Unlock. A wrong password doesn’t unlock anything.

There is no password reset

If you choose Skip - no recovery, no backup is stored. Your private key then exists only in the Keychain on that Mac. As the app warns: “If you skip this and lose this device, your encrypted screenshots cannot be recovered - not even by us. There is no reset.”

The same applies if you forget your recovery password and have no Mac that is still signed in. SuperCapture cannot decrypt your files for you. Store the password in a password manager.

Sharing encrypted captures

• Shared folders: when you share a folder with people, your Mac wraps each item’s key for every member so they can open it. The server never gets a readable copy.
• Removing someone stops them from getting keys for new items. It doesn’t remove files they have already opened or downloaded.
• Web pages: encrypted items can’t be published as a public share page, because the server can’t show a file it can’t read.

What this protects against

End-to-end encryption means the service operator can’t read your capture files. So can’t anyone who later gets access to the stored data or the database.

It relies on the service to hand out the right public keys when you share. There is currently no way to compare key fingerprints with the people you share with. It doesn’t protect against a server that deliberately substitutes a key.

It also doesn’t hide the metadata listed above.