John Kelsey[SMTP:[EMAIL PROTECTED] At 11:08 PM 3/12/03 +0100, Krister Walfridsson wrote:This is not completely true -- I have seen some high-end cards that use the PIN code entered by the user as the encryption key. And it is quite easy to do similar things on Java cards...
With any kind of reasonable PIN length, though, this isn't all that helpful, because of the small set of possible PINs. And smartcards don't generally have a lot of processing power, so making the PIN->key mapping expensive doesn't help much, either.
Every PINned SC I've seen has a very limited (typically 3) number of failed attempts before it locks itself up. Once it's locked up, it can only be reactivated by an administrator PIN, which is held at much higher security by the issuer, and not available to the card user.
I think John's point is still valid: encryption is only necessary to protect against people who bypass the standard API and somehow extract the data (microscopes, side channels?). In that case, the lock-out feature is irrelevant, and a short PIN is not much of a barrier.
- Nikita
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