Is there any software that can do this in a very user friendly way? Ideally after entering a key when installing the software, I would never know that encryption is happening.
Looks like https://www.arqbackup.com/ might meet your needs. I haven’t used it personally though, my only reservation has been that it’s not open source.
The unofficial google drive linux CLI supports encryption with custom keys too.
I got burgled back in July and the burglars came somewhat close to getting everything, fortunately they didn't take my NAS. After discussing with friends, I did buy Arq and I've been _very_ happy with it.
I then went and bought 1TB of Google Drive and now all my photos and anything else is backed up onto both Google Drive and my NAS. It's all encrypted so yeah, should be safe enough. The handy thing about the 1TB Google space is that it's shared amongst all their products, so, I don't need to think about running out of Gmail space either.
Yes that seems quite nice (if you want to go that far). It also works well with the Dropbox (and others) sync engine because it encrypts individual files as opposed to making a large sparse bundle/volume file.
Don’t think it allows you to take advantage of delta-byte syncing though because while compression algorithms can now cater for the rsync-like delta sync functionality you find in some cloud storage clients my guess is that wouldn’t be optimal for secure encryption (but I don’t know it’s just a guess) - but if you aren’t changing the files a lot the speed degradation may be outweighed by your desired outcome.
It also works well for Dropbox shared folders in case you have the need to share folders with other people but still want this additional layer of encryption.
And of course since it’s open source it may make you feel more comfortable about the encryption.
...that said though, I actually do want to say that personally I'm always very conscious of what the tradeoff is.. I like to keep my files in a flexible format that's future proof and to be able to move it around and manipulate them in a fast way. The risk with something like Cryptomator, despite it looking pretty neat and being open source etc, that if people decide to not maintain it anymore then my files are stuck in an encrypted format that one would have to develop code (or use an old OS with an old version of Cryptomator) to access them.. so I'd prefer leaving my files in Dropbox (who encrypts my files on their/our side) and on full-disk encrypted hard drives instead. But each to their own of course!
The best I have found is "Duplicati" which runs in the background of your computer and can backup to all internet backends(I use it with ondrive and box), a NAS, or a USB stick/attached drive(pretty much anything). It is open source as well! It automatically (locally) encrypts all your files after compression and does it in blocks, making it quite space efficient. It also has versioning.
https://www.duplicati.com/
It does mean of course that you can't search through your files while they are stored on the cloud or use any cloud-native editing tools on those files. For many, this is a reasonable tradeoff, but it means the encryption can't be totally transparent.
The unofficial google drive linux CLI supports encryption with custom keys too.