如何将 apdu 命令传递给命令 apdu 功能

Question

Hi am new to java card I have following data

CLA '00'
INS 'A2' nb not real value
P1  '00'
P2  '00'
LC  '08'
Data In 'EF08'
Le   '0D'

How can I write above instructions into bytes and send to this function? I need to get 9000 as success response and Data out.

 ResponseAPDU respApdu = channel.transmit(
                                 new CommandAPDU(cmd));

Answer 1

There are multiple ways to do that:

Case 1: (Not encouraged)

int cla = 0x00;
int ins = 0xA2;
int p1  = 0x00;
int p2  = 0x00;
//int LC  = 0x08;'
byte[] data = new byte[] {(byte) 0xEF, (byte) 0x08};
int le  = 0x0D;

ResponseAPDU respApdu = channel.transmit(
                             new CommandAPDU(cla, ins, p1, p2, data, le));

Case 2: (Encouraged)

byte[] apdu = new byte[] {(byte) 0x00, (byte) 0xA2, (byte) 0x00, (byte)
              0x00, (byte) 0x02, (byte) 0xEF, (byte) 0x08, (byte) 0x0D};

ResponseAPDU respApdu = channel.transmit(
                             new CommandAPDU(apdu));

Read more about CommandAPDU and CardChannel .

Case 3: (Mostly used way)

String apdu = "00A2000002EF080D"; //also u can append strings into apdu
ResponseAPDU respApdu = channel.transmit(
                             new CommandAPDU(toByteArray(apdu)));

You need a Helper function:

import javax.xml.bind.DatatypeConverter;
public static byte[] toByteArray(String s) {
    return DatatypeConverter.parseHexBinary(s);
}

Attention: The example APDU values you showed, LC '08' means the data will be 8 bytes long, but your data field is only 2 bytes long. So check LC again.