How to protect files?

Question

Data protection

Good afternoon.
How (or how) to protect files from unauthorized access? And so that this "folder" (or archive, or whatever) could be auto-backed up on a USB flash drive and / or cloud. What would be access by password, but without the ability to brute it. For example, the limit of incorrect entries is in the region of a thousand, with the counter reset after a correct entry. And that it would be possible to get access to this on any machine with "basic" means. Without installing any special software.
Of course, without any backdoors, etc.

Answer 1

Windows itself is one big backdoor. But let's say at the household level an acceptable way is a hardware flash drive with encryption + a complex password. Yes, Windows will merge the password - but why does she need it when you have a flash drive? (Of course, if you are not Assange or Snowden :) )