HTML5 cache protection (localStorage)?

Question

JavaScript

It is necessary to store conditionally secret data in the application's HTML5 cache. How to protect data from theft? How secure is localStorage? The attacker, like the application, has access to the entire machine, except for DevTools, etc. (There is no server for the usual protection mechanism.)
There is an idea: to encrypt the cache between work sessions. But then it will still be available during the next session.

Answer 1

You can't hide data in the browser. Cookies, localStorage, indexDB - everything can be accessed by the end user. Code - available.
why is there no access to DevTools?

Answer 2

encryption!!! Just encrypt what you need.