This is exactly what U2F protects you from! You can actually safely plug U2F tokens into random computers and rest assured that the keys inside cannot be clone

This is exactly what U2F protects you from! You can actually safely plug U2F tokens into random computers and rest assured that the keys inside cannot be cloned. This provides security guarantees above and beyond that of physical keys! In fact, an untrusted computer can't* even MITM the authentication process of U2F, unlike with SMS codes! (Of course, an untrusted computer could fake the UI to try and exfiltrate other info from you, but that's beyond the scope of authentication itself.) The worst a malicious client can do to a U2F token is to fry it :-) *: There's some asterisks here, but if you want to know the details check out the U2F spec or this https://www.yubico.com/blog/creating-unphishable-security-key/ https://www.yubico.com/blog/creating-unphishable-security-ke... for a more accessible explanation. Banking-grade U2F/similar tokens actually behave like hardware crypto wallets and will show the auth request metadata on an internal screen, in case the device you are plugging into is completely untrustworthy.