reading response APDU data question
Hello,
I am using the smartcardio api to read information off of a smart card. The problem I have right now is that I am having problems 'decoding' the returned data.
e.g.
To read the card number I select 3 files on the card by sending 3 commandAPDUs,
ResponseAPDU r = channel.transmit(new CommandAPDU(cardNo1APDU));
(repeated with two more commands)
I then send another command to read the 8 bytes of data from the card:
r = channel.transmit(new CommandAPDU(getCardNumberAPDU));
Then, as a test I output the returned data to see if it looks right
System.out.println(new String(r.getBytes()));
But the output is displayed as a series of characters, 'squares', question marks etc. So I am assuming that I am not decoding the data properly, but I am a bit stuck as to what to try. I have tried specifying the character set in the
String constuctor, egnew String(r.getBytes(),"UTF-8")
, but that doesn't make much difference.
I am expecting the card number to be 8 digits long.
Can anyone think what I might be doing wrong?
Thanks
[1290 byte] By [
DxMa] at [2007-11-27 10:29:47]
# 1
try
byte z[] = {(byte)0x32, 0x33, 0x34, 0x35};
String s = new String(z);
String(byte[] bytes)
Constructs a new String by decoding the specified array of bytes using the platform's default charset.
I don't know if this helps, but the constructor converts the bytes to the String Representation of the bytes received
# 3
yeah, you are right, I spent quite some time searching the internet for a toBinary mehtod, but then I just created my own. I take the byte and split it off into 2 nibbles, High Nib and Low Nib (& 0xF0, & 0x0F), and then I take each nibble and shift to get each bit to the LSB position and & by 1 to mask off extra bits. (The &1 might not be necessary, but I like to be sure) i.e.
byte nibH = (byte)(bite & 0xF0);
bit7 = (nib1 >> 7) & 1);
And viola, you have your msb, if you continue this pattern, you will get each bit from the bytes, and then you can put this into a string or whatever you like. I hope that was helpful. Also, sorry about my prev post, that one would still cause the ugly chars as before ;-)
# 4
public static byte[] hexStringToByteArray(String s) {
byte[] retval = new byte[s.length() / 2];
for (int i = 0; i < retval.length; i++)
retval[i] = (byte) Integer.parseInt(s.substring(i * 2, i * 2 + 2), 16);
return retval;
}
public static String byteArrayToHexString(byte[] bytes) {
StringBuffer stringBuffer = new StringBuffer();
for (int i = 0; i < bytes.length; i++)
stringBuffer.append(String.format("%02X", bytes[i]));
return stringBuffer.toString();
}
ausa at 2007-7-28 17:59:29 >
