AES is already post quantum crypto so that sounds a bit marketingy.

I would get a backup tool that offers encryption, which is most of them. Popular choices are: tarsnap, restic and Borg.

Nextcloud has collabora integrated.

I would put this stuff behind VPN.

Get a refurbished Lenovo thinkpad t470 or so from ebay, make sure it has full HD and comes from a commercial shop. All the Thinkpads work great with Ubuntu. They are good quality business notebooks, easy to repair with good parts availability. You can probably get one around 150 or so.

I repaired laptops for a living for a while and Thinkpads were always my favorite.

It’s a gas where the chemical reaction of the combustion has produced enough energy to heat it up to a temperature where it emits visible light. Kind of like a glowing piece of metal, but in gas form.

It’s a mixture of black body radiation and individual spectral lines.

The spectral lines happen when electrons fall from a high to a low energy state and the energy difference is emitted as light.

Black body radiation describes the fact that everything constantly emits electromagnetic radiation (=light). But what kind of light depends on the temperature with colder bodies like us humans emitting infrared whereas warmer bodies like the sun emit visible light. That is also why light temperature is a thing and the unit is Kelvin.

Here are some graphs and stuff: https://physics.stackexchange.com/questions/648273/does-fire-emit-black-body-radiation

If you assume everything is compromised, there is no safety. You have to trust something at some point.

Usually, speaking from a professional IT perspective, people trust encryption. Once you do that, it does not matter how safe or unsafe the place where you store your data is.

AES, the encryption standard used by pretty much everything, is safe. It has not been weakened in any meaningful way since its inception and is also quantum - safe.

You could use for example openssl or Veracrypt or even just 7zip to encrypt it. If you don’t trust these tools, encrypt it twice with two different ones, just put a txt file next to it with the exact steps to decrypt, because you will forget in which order you have done things.

Personally I have a homeserver that is encrypted at rest and then it uses restic to store encrypted backups in the cloud.

Thank you, I deleted my post so as to not share false info.

A thing I want to point out about publicly traded companies is that they are legally required to maximize shareholder profit.

So if a CEO refuses to do something immoral that would increase profits, the shareholders can sue to have them fired and replaced with someone else.

Not protecting any company here but this entire system is fucked and clearly leads to enshittyfication and immoral actions becoming the norm.