That depends on how you're storing the files. I was really just trying to highlight that for deduplication across files you need to deduplicate before you encrypt.
Re:Rclone: rsync for cloud storage
by Dylan16807 on Thursday September 01, 2016 @03:40AM
(#12403635)
Guess the encryption key? That shouldn't be possible, even if you use something as terrible as ECB.
If you don't CBC, wherever is on the cloud side will have two files with one block off. Let's assume the file is a txt file. For smaller cipher block sizes, it is becoming very easy to guess your encryption key.
Tldr, you want any attacker to lose any diff ability on your encrypted data.