The dirty secret is that the default encryption key on Fortigate firewalls is shared across ALL Fortigates (and a couple other platforms) and has been compromised for a long time. So if you haven't set up your own key through enabling the private-data-encryption feature, you too can have your passwords cracked and exposed to the Internet.
Follow the hardening docs and don't forget this step:
https://community.fortinet.com/t5/FortiGate/Technical-Tip-How-to-enable-private-data-encryption-feature-on-a/ta-p/339071