How secure are my hidden formulas?

How secure are my hidden formulas?

Hello, 

I am writing a spreadsheet to be shown on a wix website that uses confidential formulas that cannot be shared or viewed by anyone, including (for safety sake) zoho. When i use the hide formulas function, how secure is this? and what happens if the hidden function is down for a day or so, will by formulas be available to see? also will they be able to be viewed by Zoho programmers or employees?

Thank you for your support!!
-Kenneth M.. Brooks III