For Kleopatra we need an action icon for smartcard management. In the past we have used the "secure-card" device icon (from the oxygen theme). Smartcards are either actual cards (like credit cards with a chip) or, nowadays probably more common, USB tokens (like Yubikey). Ideally, the new icon would be called "secure-card" (as in oxygen) because then it would work out of the box. In breeze there is skrooge_credit_card, but that's a bit anachronistic with the magnetic strip. Crypto smartcards don't have a "dump" magnetic strip.
I was about to file something like this. This is what I was writing when I discovered this: Having an icon for cryptographic hardware tokens / smartcard / yubikey / nitrokey / gnuK / others would be nice. In some dialogs that lists available cryptographic private keys it would be nice to be able to visually distinguish keys that is on a hardware token. The icon will likely be used at least by kmail, kleopatra and okular https://www.floss-shop.de/en/security-privacy/smartcards/13/openpgp-smart-card-v3.4 https://spin.atomicobject.com/2014/02/09/gnupg-openpgp-smartcard/ https://en.wikipedia.org/wiki/OpenPGP_card could all be used as inspiration. Or maybe a "classic" key with a usb plug at the end.
Oh, I think we can close this issue. At some point in Kleopatra we started using the "auth-sim" family for smartcard icons and I am quite happy with it. "auth-sim-symbolic" "auth-sim-locked" etc. I am not sure if they were new after this ticket but they work nicely in my opinion.
auth sim seems to be usable. I was just told that the only icon we have is the miniature https://invent.kde.org/pim/libkleo/-/blob/master/src/pics/smartcard.xpm