How to encrypt information in the cloud?

Question

linux

There is a working folder containing thousands of small files. Almost always only a few are modified, sometimes almost all. Only ~1Gb.
There is another folder containing large files ~5-20Gb each. Change extremely rarely, mostly deleted or created.
I want these folders to be saved in the background to the cloud in encrypted form, and on computers to be available in decrypted form, available for processing.
OS Ubuntu 14.04 and 15.04. I'm friends with the console) HDD space is enough to store all the data in duplicate. But it is desirable to save the resource of RAM and processor, because. I often use a laptop (i5 1700, 8Gb).
What to encrypt?
psInteraction with the cloud API is not necessary, rather the opposite. I think about this option: unencrypted files are stored on the computer. I modify the file, it is encrypted and encrypted in the folder that is synchronized with the cloud. And it's all around the clock in the background.

Answer 1

In general, there is only one solution - EncFS.
habrahabr.ru/post/209500

Answer 2

Well, you've already written half of the solution in a postscript.
File change tracking - with inotify.

Answer 3

Boxcryptor classic
https://www.boxcryptor.com/en/classic
encrypts one folder for free.
you can try it, like it - or buy it, or move the folders to one parent and encrypt it.
I don’t know how it is in Linux, in win I have the following use case with dropbox - the dropbox is synchronized by the standard utility on the hard drive, in its folder one folder is allocated for encrypted content. The content is encrypted with a boxscript. After entering the password, the boxscriptor mounts a virtual disk that you can freely work with. In fact, the data is encrypted and in this form is synchronized with the dropbox.