Changing key at PICC or Application level for a new desfire EV1 8K

Forum / MIFARE SDK / Changing key at PICC or Application level for a new desfire EV1 8K

  • 29. October 2016 at 6:15
    Hi
    I am really struggling to change the default Zero keys in a new desfire tag. I get the response 0x1E. I appreciate if anybody can help me where I am going wrong. Thanks in advance. Here is my story
    I am authenticating using command 0A and spot on success
    <> 48 F1 C7 B6 11 1A F6 B4 91 AF
    <> 36 82 12 C7 67 70 A6 1C 91 00

    The following are the values at various stages.

    RndA : 08-88-A0-5D-4C-4B-10-96
    RndB : 17-DC-EE-3C-C9-BD-8B-41
    Session Key : 08-88-A0-5D-17-DC-EE-3C
    New Key : 11-22-33-44-55-66-77-88-99-AA-BB-CC-DD-EE-FF-10
    CRC : 10-CA
    Preparing cmd to change key 0 of an application. I have selected this application before running the command.
    ============================================================================================================
    The change key for this application is set to Application Master Key which is default Zeroes.

    plain data: 11-22-33-44-55-66-77-88-99-AA-BB-CC-DD-EE-FF-10-10-CA-00-00-00-00-00-00
    enciphered data : 05-1B-21-74-44-AD-47-C7-1E-14-97-BF-32-4A-8A-32-55-E8-FE-E4-55-70-4D-7D
    cmd: 00-05-1B-21-74-44-AD-47-C7-1E-14-97-BF-32-4A-8A-32-55-E8-FE-E4-55-70-4D-7D

    PC/SC command to ACR122u reader/writer
    --------------------------------------
    <> 91 1E
    + 0  |  - 0

    Re: Changing key at PICC or Application level for a new desfire EV1 8K

    29. October 2016 at 6:36
    This is in continuation of above post. Misses last 2 lines ( cannot figure out how to edit the topic once submitted :-)
    PC/SC command to ACR122u reader/writer
    --------------------------------------
    <> 91 1E

    + 0  |  - 0

    Re: Changing key at PICC or Application level for a new desfire EV1 8K

    7. November 2016 at 18:23
    Hi there, I have sorted the issues and would like to close this post. There is a clean explanation in Mifare Desfire EV1 examples and hints pdf. It is under NDA though.

    Thanks
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    Re: Changing key at PICC or Application level for a new desfire EV1 8K

    14. November 2016 at 10:34
    Hi Narendc,

    You have to be careful, if you want to change a DESFire key. Before you can overwrite a key you have to prove, that you are allowed to do that—even if the key was not used before! Before you can change a key, you have to authenticate to key number with the old key value. Please have a look to this example:

    https://www.mifare.net/support/forum/topic/cannot-create-desfire-ev1-aplication-with-aes-key/

    Kind regards,
    The TapLinx Team
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