Old PC as Hardware Security Module?

[Casey Jones]

Zeljko Vrba wrote:
> there's NO WAY to prevent this attack.  Not even
> separate PIN entry device helps,

The attack that I'm referring to here which the PIN pad is meant to 
prevent, is only the unlimited use of the smart card. An attacker can 
still make a signature or decrypt something, but only one for each time 
you enter a PIN on the PIN pad(or press the authorize button if 
something like that exists). Soon you would notice that what you wanted 
signed or decrypted wasn't getting signed or decrypted, or was done wrong.

I just thought of another feature. The card could require that you enter 
what operation you wanted performed on the PIN pad. For example if you 
want a signature, you enter a one before you enter the PIN. The card 
could check that in fact gpg has requested a signature and not a 
decryption. Before a decryption enter a two. This would limit the 
attacker not only in the number of unauthorized uses but in the type as 
well.