Flutter pdf retrieve and save

I have an online study app. There is a module in it , in which user reads from the pdf, but every time it has be be downloaded and user keeps waiting each time. I want someone to create a module that could download a pdf when clicked first time on a button. Now the downloaded pdf should be saved in such a way that it should not be visible to user. When user clicks on the same button again, it should retreive the pdf from internal storage that we saved earlier which hence saves the time in downloading. If user logs out , the file shall be deleted. some technical help i can do: use may create a sqlite database in flutter app in which you could store pdf as BLOB and save name of the file as its key. We will create the name of the file unique. now when user clicks on it agian, it will check the name of the file in the sqlite database . If it is present there, app should cast BLOB to pdf agian and show it to user.