New Application Default Key

[onyekachi]

Please help me comprehend the expected behavior in this scenario

First, I have taking a Blank Desfire card and formats it.
2. I change the default key from DESFIRE_DEFAULT_KEY to COMP_DEFAULT_KEY

objDESFireEV1.changeKey( 0, DESFIRE_DEFAULT_KEY, (byte)0x00, COMP_DEFAULT_KEY, (byte)0, DESFireEV1.KeyType.TWOK3DES,

                                 IKeyConstants.DIV_OPTION_NODIVERSIFICATION,IKeyConstants.DIV_OPTION_NODIVERSIFICATION, null );

3. I authenticate the new Master Key(COMP_DEFAULT_KEY) and it was successful

4. I create a new Application with a new AppID(NewAppID) as shown below

objDESFireEV1.createApplication(NewAppId, getKeySettings(objDESFireEV1), 2, DESFireEV1.KeyType.TWOK3DES); 

Question
To authenticate the new Application ID should one use the default Desfire Key as shown below

 objDESFireEV1.selectApplication(newAppId);

  objDESFireEV1.authenticate(AuthType.Native, DESFIRE_DEFAULT_KEY  , (byte) 0, 0, (byte) 0, null);

or the COMP_DEFAULT_KEY as shown below

objDESFireEV1.selectApplication(newAppId);

   objDESFireEV1.authenticate(AuthType.Native, COMP_DEFAULT_KEY , (byte) 0, 0, (byte) 0, null);

I thought the later with COMP_DEFAULT_KEY sice its now the cards new default master key, but its falling

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[mifaresdk]

Hi Onyekachi,

Changing the master key #0 is independent of the pre-loaded values for the other keys. If you want to change key #1 you have to authenticate with the default key (00…000) before changing key #1 to another value.

Kind regards,
The MIFARE Team

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[onyekachi]

Thank you very much for the prompt response,

With the information you provided in-mind, is it possible to prevent one from adding an application to a Desfire card, if they know its a Desfire card and has knowledge of adding application to a card, How does changing the Masterkey prevent one from adding application to the card in anyway?

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[mifaresdk]

Hi Onyekachi,

Yes you can prevent users from creating new applications. This is part of the PICC Master Key setting. Please keep in mind, if you select AID=000000 and authenticate with key #0 it is the PICC Master Key and if AID!=000000 it is the Application Master Key.

This is coded as part of the ChangeKeySettings() command. You can set options for “configuration is changeable yes/no”, “CreateApplication/DeleteApplication is permitted only with PICC Master Key authentication”, “Successful PICC Master Key authentication is required for GatApplications() and GetKeySettings()” etc.

The MIFARE Team

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