Creates a signing key that stays on this phone and cannot be copied off it. Send the public key to the admin to be added to the signer list.
Safe to send over anything — this is the public half. The signing key itself never leaves this phone. The admin pastes it into the root console, which re-signs the signer list.
Only so the admin can see this key in the fleet list. The key is signed on this phone and works whether or not this is filled in, so leave it blank if there is no signal.