Well I should perhaps elaborate: does it offer end to end authenticated encryption with keys that never leave user’s device in an open source program?

Another point, I suppose that backblaze comes with dedup and compression?

Re: encryption, long-story short, the keys used to decrypt your data are stored in their data centers, but you can also encrypt those keys with a symmetric key which only you know. [0]

Re dedup/compression, it's a bit irrelevant because their plans are unmetered.

[0] https://help.backblaze.com/hc/en-us/articles/217664688-Can-y...

> [...] but you can also encrypt those keys with a symmetric key which only you know

...until you need to restore from backup. You then have to sign in on the Backblaze website and enter that key, the files you are trying to restore are then decrypted on their end, and bundled up and sent to you.

They say that the key is only ever in RAM, and only then briefly.

regarding unmetered, i gave up on backblaze as their network connection seems incredibly slow. i think asking for compression and dedup is very relevant with them

Yeah, their stock answer is "use more threads" but I could never use more than 30-50% of my upstream bandwidth. It doesn't help that the client is slow itself and seems to sometimes just stop backing up.