Attacks only get better over time. In a sense, there are security flaws in every computer program, which only get clearer with time. The issue here is that these flaws are in a CPU, which is a component that's very difficult to change, so the existence of security flaws (that will only become clearer over time) seems worse than if it were in software. Maybe it's worse because of economic reasons (all the computers we have today will become obsolete because of security problems) or maybe because it's impossible to mitigate the flaws (the bugs are physically part of the hardware).

Also I remember that cryptographers consider any leaking of information about a secret to be a break. They call this "semantic security". Maybe there's something special about crypto that means people have to be maximally paranoid. I wonder what level of paranoia is appropriate for CPUs.

Actually, if NetSpectre can already leak information about a plaintext or secret key, then that already breaks all of cryptography from some cryptographers' point of view.

Another thing: Nation states may learn how to execute Spectre attacks faster than academia does. Then again, those same nation states would also want to switch to non-Spectre-prone computers, which would be visible enough for other people to start changing. Or maybe I'm putting too much faith in the IT skills of nation states.

Given all that, I don't know what safety margin is appropriate for CPUs. When do we consider all of our CPUs to be broken? Is it when Spectre attacks are being used to extract our financial info en masse? Is it soon? Or is it when governments start changing their computers (assuming governments are even that clever -- see the NHS and Wannacry)?

This kind of attack is catastrophic in cryptography.

Only on some popular OS which told you over all the years that kernel memory is safe to store keys. Of course it is not. They didn't listen, and it's getting worse.

yeah, like, shortening a secret key by 15 bits per hour would save a looot of brute force...

Extracting a key over only a few days pretty much is a killer, heck even a few months for a high value target is game over think what happens if you get the private key of a key internet service like Google or Facebook, not to mention .gov or .mil sites.

It can go up to 125 bytes per second, maybe more. I've not finished reading the pdf yet

Depends on the level of automation possible in deploying a wide-scale attack, too.

Run some scripts, check on it six months later...oh look, we have SSL private keys for the X domains now.