Encryption of data in smart cards

[Nikita Borisov]

Trei, Peter wrote:
>>John Kelsey[SMTP:kelsey.j at ix.netcom.com]
>>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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