how can i protect my database with rules

[abdou8n]

hello
FireSharp work with authSecret so , so my server will bypass my Realtime Database Rules
even if my rules are ;

{
  "rules": {
    ".read": false,
    ".write": false
  }
}

i have a website (asp.net core 3) with input fields , and all data entered will be saved to firebase database child (realtime database)

can can i protect my database with security rules ?
is it safe to put the auth secret in my own server ?