How can i generate MAC (Message Authentication code)?

[micro24]

Hi I am using your code, it is very well, thank 's for your code but i have a problem, i do not know how can i generate MAC(message authentication code) ? please guidance me.

Best Regards Farnaz

[AndreasFagschlunger]

Hi Farnaz!

For which purpose do you need the MAC? Usually there is no MAC computation needed for offline authorization. In case of online authorization, you usually compute a MAC over the ISO 8583 messages. The standard algorithm for MAC is 3DES CBC, as far as I know you can compute it with plain Java - if not try http://www.bouncycastle.org/. But if you're needing MAC for online authorization, you should get more detailed information from your Issuer.

Best regards, Andreas

[micro24]

Hi

Thank you for your answering,I know that i can calculate MAC with java and bouncycastle but i want to calculate mac with Device(XFS). I calculated PIN BLOCK with your application.I have all of the keys for example Master Key,... Does your application supports this feature? or How can i use your application for generating MAC?

Best Regards Farnaz

[micro24]

In your Project I write a CryptClass that extends from Struct with below fields:

    private LPSTR key = new LPSTR();
private LPSTR keyEncKey = new LPSTR();
private LPSTR startValueKey = new LPSTR();
private LPSTR startValue = new LPSTR();
private BYTE padding = new BYTE();
private BYTE compression = new BYTE();
private LPSTR cryptData = new LPSTR();
private WORD mode = new WORD();
private WORD algorithm = new WORD();

I fill fields and send command with below code this code writes in a class( this class implements XfsEventNotification) but after excute(below code) i get this error: "at.o2xfs.xfs.XfsServiceException: WFS_ERR_INTERNAL_ERROR(-15)" ,

     public void execute() {
    XfsExecuteCommand command = new XfsExecuteCommand(pinService,
            PINExecuteCommand.CRYPT, pinCrypt);
    try {
        command.execute(this);
    } catch (XfsException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
 } 

please tell me. How can i solve my problem?

Best Regards Farnaz

[AndreasFagschlunger]

I've already computed MAC with WFS_CMD_PIN_CRYPT, I try to push the code later.

[micro24]

Thank you for your response.

[AndreasFagschlunger]

I pushed the necessary Struct and Command, some method like the following should do the trick:

    public byte[] createMAC(byte[] data) throws XfsException {
        WfsPinCrypt pinCrypt = new WfsPinCrypt();
        pinCrypt.allocate();
        pinCrypt.setMode(PinMode.ENCRYPT);
        pinCrypt.setKey(...);
        pinCrypt.setAlgorithm(PINAlgorithm.TRIDESMAC);
        pinCrypt.setStartValue(new byte[8]);
        pinCrypt.setCryptData(data);
        return new PinCryptCommand(pinService, pinCrypt).call().getData();
    }

Note, you must specify the key (setKey) loaded in the PIN Pad. Also the start value is, as far as I know, used for padding. Since the data is already padded, I simply use a empty array.

[micro24]

Hi Thank you for your efforts and follow.