Smartcards and tokens

Peter Lebbing peter at
Fri Dec 16 12:34:14 CET 2016

On 15/12/16 22:17, Damien Goutte-Gattat wrote:
> I'll admit readily that I am not an expert on this, but I don't see how
> that could be feasible without the help of the host PC--meaning your
> opponent would have to both (1) compromise your PC and (2) send you a
> malicious token. But if he could compromise your PC, he would have no
> need for a malicious token.

However, the defining property of a smartcard is that in principle, the
private key cannot be extracted. That no longer holds for the party who
backdoored the smartcard, since they could add a special command that
extracts the private key.

> I guess your attacker could use a USB token as the mean to compromise
> your PC (names like "Bad USB" come to mind)

Also note that someone could "borrow" your card without you noticing,
rather than compromise your PC. This does depend on physically close
attackers being in your threat model. Your USB token could actually have
been compromised remotely on a different system, as a roundabout way of
compromising your machine in the end. So that one is actually possible
for remote attackers.



I use the GNU Privacy Guard (GnuPG) in combination with Enigmail.
You can send me encrypted mail if you want some privacy.
My key is available at <>

More information about the Gnupg-users mailing list