> In the perfect world yes ! but, sadly, people sometimes doesn't follow
> correctly the ISO7816 or misunderstood it. I have cards (W4SC as an
> example) which send back a GET RESPONSE even for a APDU without data.
> This is really annoying as I have to modify my application to take care
> of this kind of cards.
That is because there is no way for the card to differentiate between a case
3 and case 4 APDU. Independent of whether the application specifies Le or
not, the command is always send to the card with P3 = Lc. It is the
transport layer T=0, that must detect a Le passed from the application and
enable GET RESPONSE processing.
On the application level case 1 to case 4 look like
Case 1: CLA INS P1 P2
Case 2: CLA INS P1 P2 Le
Case 3: CLA INS P1 P2 Lc Data
Case 4: CLA INS P1 P2 Lc Data Le
In T=1 these APDUs are transported transparently. In T=0 they are mapped to
Case 1: CLA INS P1 P2 P3 = 00
Case 2: CLA INS P1 P2 P3=Le
Case 3: CLA INS P1 P2 P3=Lc Data
Case 4: CLA INS P1 P2 P3=Lc Data and subsequent GET RESPONSE.
Andreas
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