How to protect from modifying/alter webview cache file in android programmatically

I am creating an webview android app. while using our app, its creating cache files in default location.

while loading app at first time, i am saving all files in cache file, For next time, retrieving all files from same cache location, for fast access, instead of remote download.

so, In this moment, There is a possibilities to tamper my cache file in android mobile. so, i want to protect or secure from modifying the cache files in my mobile( if suppose my mobile theft).

I have searched and saw few sites, i am unable to found exact solution, which i am expecting?

Note: I want to restrict/protect/secure the cache file altering or modifying from tamper/theft person.

any suggestion or solution would be appreciated.

Thanks Advance

Referred websites:

https://developer.android.com/reference/android/webkit/WebSettings

Any option to restrict our Android application cache being cleared?

Caching in Android webview

Is it possible to access the WebView cache?

Encrypt the WebView Cache on Android

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