- sign your emails digitally - login to secure websites with your id card (bank, DMV, taxes, …). Sometimes you can only do it with the ID card - they opened many of their tools, so you can design your website to allow login with Spain's ID cards (that was a fun project)
Even if not affected, it would be nice to hear an official comment.
I was discussing this with someone from Belgium and we agreed that silence from the Belgian government meant only one thing: nobody used the service. (Specifically: Belgian cards are the older Gemalto generation, thus not affected, like the older Estonian IDs.)
Maybe Spain happens to use ECC keys too.
New certificates are generated on the chip, and the public part is then transmitted to the government public keys directory.