Session specific files

[DanielFields]

If you place them in the wwwroot\files folder, or any subfolder under that, they cannot be accessed without creating a session.  You could also export them on-demand into the UserCache.  Doing it that way would make them temporary, and they would get deleted after use.  The UserCache is not accessible through any means but your application.

WebApplication.UserCacheDir gets you a unique folder for each session.