Your device will not attest to this if you install your own operating system, if you root your phone, if you do anything that they don't like, anything at all.
You install your bank's app and try to use it. The bank's servers ask for the attestation. You will not have one. They decide you cannot be trusted and deny you service.
Even if you can program your own keys into your device, nobody is gonna trust those keys. Why would your bank trust your own keys? They'll trust Google's keys, Apple's keys, the government's keys. You? You don't get to participate.
The corporations and governments want to own your computer. They demand cryptographic proof that your device is owned by them and that they have complete control. If you don't provide it, you're banned and ostracized from everything.
Suddenly it's mandatory because the device is a phone?
For the website, it's also easy, even with PSD2 you can just get a physical TAN generator.
My point was that you can't do it *without hardware attestation*. You can choose between 1. a smartphone with hardware attestation, or 2. a physical TAN generator with hardware attestation.
It used to be that Linux users like me were exempt but at some point they added Linux support. Now there's a goddamn AUR package for this thing.
https://aur.archlinux.org/packages/warsaw
https://aur.archlinux.org/packages/warsaw-bin
> Banking security tool developed by GAS Tecnologia
Yeah. Banking security tool. Who the fuck even knows what it does? It sure as hell isn't me. That thing is not going anywhere near my system.
What is the particular threat model of a rooted phone?
Maybe some bank would allow you to use some third party two factor authentication device to log in sometimes, but most (if not all) would require you to use their "app".