[opminion]

I wonder if the Client Certificates mentioned in the article are the same thing as certificates used in Spain for interaction with government agencies, the so called "certificado digital".

In that case they are not "rarely used", but I would agree that they their usability is abysmal.

[AshamedCaptain]

Yes, they are. There was an EU wide push to use these as a form of online public authentication.

I think a lot more people used keygen than this article seems to claim, even without knowing it. The alternative on IE was either an activeX control or a java applet (neither feasible on a mozilla browser since the applet wont have acess to the browser certificate storage).

When Mozilla deprecated keygen, these services never recovered. The proposed alternatives had even worse UI and were even less portable.

[idndoxheo]

ah yes, the good old bay-area-bubble.

if your two friends don't use a feature, it can be dropped. that's the origin of sites only working with IE6 buttons (to keep with the age of the article) or noways things crashing unless your browser implements the latest buggy and non standard features that chrome is pushing.

also, remember, even the standard stuff (w3c) was always written and worked on folks in the payroll of companies whose main business was selling advertisement.

[Avamander]

Yes, highly likely it's mTLS like in other EU countries. Though some countries have a longer track-record and better client software (and legislative enforcement of support) than others, providing a smoother experience.

Most of the stumbles seem to be from countries and the EU not cooperating with browser vendors to fix the rough edges. Unfortunate but probably a tragedy of the commons.