Using SSH keys
Key files, passphrases, what formats work, and what to do with a .ppk.
Before you start
- A private key file in OpenSSH format
SSH and file transfer both authenticate with a private key as well as a password. Choose Private key on the connection form.
Choosing a key
Any key already in ~/.ssh — that is C:\Users\you\.ssh\id_ed25519 and friends — is offered as a one-click suggestion under the key field. Most people have exactly one, and that is the whole interaction. Otherwise use Browse, which opens in .ssh.
The key file is never copied. Only its path is stored, and the file stays where it is under whatever permissions you have already given it.
Passphrases
If the key has one, the password field becomes the passphrase. If it does not — which is common — leave it blank and connect. Ticking Save passphrase encrypts it exactly as a password is; leaving it unticked stores nothing.
Formats that work
- OpenSSH format: Ed25519, RSA and ECDSA, encrypted or not.
- Legacy PEM RSA.
PuTTY .ppk files
Not read directly. If you point the app at one it says so and names the conversion steps rather than failing with a parse error. In PuTTYgen: Load your key, then Conversions → Export OpenSSH key, and select the exported file here. The detection is on file content, so a .ppk renamed to id_rsa is still recognised as one.
What is not supported
There is no SSH agent support. Pageant and ssh-agent are not consulted; the key is read from a file. There is also no jump-host or port-forwarding support, so a key that only gets you as far as a bastion will not help here.
Generating a key
Windows ships OpenSSH. In PowerShell: ssh-keygen -t ed25519. Accept the default path and it lands where the app will offer it. Put the matching .pub contents into the device’s authorised keys.