can we use conditionnal content to resctrict content to a password
for instance : you ave a text field, you have to enter a code, and only if it checks content is displaid ?
No, Conditional Content doesn't have a built-in feature like that.
You could code your own password field, which stores the state (whether a user has entered it correctly) in the cookies or session or database. And then let Conditional Content check for that state via the PHP condition (which you would also need to write the appropriate PHP code for yourself).