SharedKey(: String, : String, : Long? = null)
An identity where every device knows the same secret key. This is a simplistic authentication mode which is normally only suitable for private apps where all the users and devices are trusted.
appName - the name of the app, specified in domain format, e.g. "app.ditto.live". All peers must use the same app name to communicate.
sharedKey - a base64-encoded DER private key. Refer to Ditto documentation for details about generating shared keys.
siteID - the site ID for the device. For shared key mode, this can be left unspecified to choose a random number.