Author of the blog here and main opkssh contributor. The title is wrong but this is OpenSSH and not a whole new implementation.

opkssh uses the OpenSSH AuthorizedKeysCommand configuration option like AWS instance-connect to add OpenID Connect validation to OpenSSH authentication.

``` opkssh login ```

Generates a valid ssh key in `~/.ssh/`

Then run bog standard ssh or sftp

``` ssh user@hostname ```

ssh will pull this ssh key from `~/.ssh/` and send it to sshd running on your server. If this key isn't in an AuthorizedKeys file sshd will send it to the AuthorizedKeysCommand which if configured to be `opkssh` will check your OpenID Connect credentials.