What's the difference between APDU and TPDU?

[BirdKing]

What's the difference between APDU and TPDU for javacard ?

[Ellisun]

The TPDU (Transport Protocol Data Unit) is a message encapsulation format where there are several bytes of routing header added to the front of the payload message.
The processing overhead of the TPDU has two components: the overhead TPDU and the overhead per byte.

The APDU (Application Protocol Data Unit) is the communication unit between a reader and a card. The structure of an APDU is defined by the ISO 7816 standards.
There are two categories of APDUs: command APDUs and response APDUs.

[BirdKing]

thanks very much.
I want to implement CCID on APDU level. But I'm confused with that how to process PCB, NAD and so on ?

[owlstead]

Yes, things like the NAD would be part of the TPDU, not the APDU. So that's not possible.

[BirdKing]

And I need not process S block and R block too ?

[BirdKing]

TPDU is without PCB. The S block and the R block should be absence. Oh, I'm so foolish.
But how to process the PPS?

[BirdKing]

On APDU level， CCID has a setParamters(0x61) command to set the GT, WT and protocol. So I think it doesn't need PPS.

[BirdKing]

On APDU level, how to process wtx or 0x60?
In CCID specification I can see "If the ICC request time extension, by using a NULL proceduce byte (0x60) in T=0 protocol or S(wtx) in T=1 prptocol, the CCID informs the host of this request." But I annot understand very well.

[BirdKing]

On APDU level, if the 8th word of pc_to_rdr_xfrblock is 0x0010 indicates the abData field is empty. This empty xfrblock could take place of s wtx in T=1 or T=0.

[BirdKing]

The empty xfrblock also replace the ack in extend apdu.