Reply To: DESFire changeKey Exception

[mifaresdk]

Hi,

it is very easy to change the for example the Master Key of a DESFire EV1 with the MIFARE SDK Advanced.
Let us assume you extend the example app enclosed with the SDK. There are keys defined:

  /**

   * 16 bytes 2KTDES Key.

   */

  public static final byte[] KEY_2KTDES = { (byte) 0x00, (byte) 0x00,

                                            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,

                                            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,

                                            (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00 };



  public static final byte[] KEY_2KTDES_ALT = { (byte) 0xff, (byte) 0xff,

                                            (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff,

                                            (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff,

                                            (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff };

The key definition KEY_2KTDES is already defined, KEY_2KTDES_ALT is added from me.
Let us append the keys to the software keystore:

  ks.formatKeyEntry(2, IKeyConstants.KeyType.KEYSTORE_KEY_TYPE_2K3DES);

  ks.setKey(2, (byte) 0, IKeyConstants.KeyType.KEYSTORE_KEY_TYPE_2K3DES, KEY_2KTDES);

  // ...

  ks.formatKeyEntry( 5, IKeyConstants.KeyType.KEYSTORE_KEY_TYPE_2K3DES );

  ks.setKey( 5, (byte) 0, IKeyConstants.KeyType.KEYSTORE_KEY_TYPE_2K3DES, KEY_2KTDES_ALT );

Now we can change the key with the SDK. I have changed the method desfireEV1CardLogic() from the sample app:

  //...

  objDESFireEV1.connectL4();

  objDESFireEV1.authenticate( AuthType.Native, 2, (byte) 0, 0, (byte) 0, null);

  objDESFireEV1.setTimeout( 2000 );

		

  showMessage( "Authenticated with key 2", 'd');

			

  objDESFireEV1.changeKey( 0, 2, (byte) 0, 5, (byte) 0, DESFire.KeyType.TWOK3DES,

	                 IKeyConstants.DIV_OPTION_NODIVERSIFICATION,

                        IKeyConstants.DIV_OPTION_NODIVERSIFICATION, null );

  objDESFireEV1.setTimeout( 2000 );



  showMessage( "Key changed from 2 to 5", 'd');



  objDESFireEV1.authenticate( AuthType.Native, 5, (byte) 0, 0, (byte) 0, null );

  objDESFireEV1.setTimeout( 2000 );

			

  showMessage( "Authenticated with key 5", 'd');



  objDESFireEV1.closeL4();

  //...

This works and does not throw an exception.

It seems that you have a mismatch in your

changeKey()

method. You set

NO_DIVERSIFICATION

but set an diversification input.

Regards,
The MIFARE Team

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