Sync through a folder

Folder sync keeps the hosts, keys, snippets and settings of devices without a Sternway account in step, through a folder that a sync tool you already use carries between them: Dropbox, OneDrive, Google Drive for desktop, iCloud Drive for Windows, Syncthing or a network share. Sternway writes encrypted files there and reads the ones your other devices wrote. The app itself sends nothing over the network for it.

The desktop app and the Android app offer it. It is for devices without an account: it cannot be turned on while an account is signed in, and signing in to an account turns it off.

Set it up on the first device

1. Open Settings › Account & Sync › Sync through a folder.
2. Choose the Folder, for example your Dropbox folder. On Android, Choose folder… opens the system’s folder picker: pick a folder on the phone that a sync app keeps in step with your computers (Syncthing is the dependable choice), and allow Sternway to use it.
3. Choose a Sync passphrase of at least 12 characters and type it twice. A few unrelated words are a good choice. Keep it in your password manager: a new device needs it.

Sternway makes a Sternway Sync folder inside the one you chose and writes everything in your local vault there.

Join from another device

Once the sync tool has brought the Sternway Sync folder over: the same screen, the same folder. Sternway sees that folder sync is already set up there and asks for the passphrase once. This device’s own hosts and keys are added; nothing on it is replaced.

From then on every change is written within a second, and the folder is read when the app starts, after each change and every 30 seconds. Sync now reads and writes at once. The phone reads the folder while the app is open, not in the background.

Check on it

The status shows what the folder holds, when this device last read and wrote it, the devices writing to it and any trouble the sync tool caused, such as files still being copied or two key files.

Turn it off

Turn off stops this device reading and writing the folder. Its hosts and keys stay, and the folder keeps its files for the other devices.

If you forget the passphrase

The devices that already sync keep working: they hold the folder’s key. A new device cannot join. To start over, turn folder sync off on every device and set it up again in a new folder (or after deleting the Sternway Sync folder), with a new passphrase. Nothing on the devices is lost.

What the sync tool can see

Random file names, file sizes rounded up to a power of two, the times files were written, and the key file sternway-key.json, which holds the folder’s key wrapped under your passphrase. Not your host names, addresses, user names, passwords, keys, snippets, settings or device names. Because the key file is where the sync tool’s company can read it, anyone who gets it can try passphrases offline: that is why the passphrase must be long.

Good to know

• Session recordings, and session log entries made while folder sync is on, are not written to the folder.
• Settings › Security › Sync keys and identities applies here too: off, keys and identities stay on each device and host passwords are left out.
• A read that would remove many items holds the removals and asks first, with Keep my local data as the default, as account sync does.
• When two devices edit the same host before either saw the other’s change, the losing edit is kept as a copy named “… (conflict)”. See How sync and conflicts work.
• On Android, only Android’s own storage has been tried in testing; no cloud provider’s folder (Google Drive, Dropbox) has been.