Re: [Globalplatform-developers] Card Challenge generation on SCP93

[Karsten O. <wid...@t-...>]

Hi,


The test vector from the SCP03 test should be OK. Could you describe
your problem? You are not able to replicate the result from the test
with your own code? A step-by-step debugging of the scp03Test in e.g.
Eclipse C/C++ IDE should give you all the intermediate steps so that you
can compare the libraries and your result.


What is the goal? Implement the server side on a smart card? Add support
for a different programming language? I think there are already OS
projects for Java, Python and C.


Karsten

On 30/11/2020 15:21, Sette Agostino via Globalplatform-developers wrote:
>
> Hi,
>
>  
>
> I am trying to develop my own SCP03 protocol and for this reason I
> cloned this
>
>  
>
> git clone https://git.code.sf.net/p/globalplatform/git globalplatform-git
>
>  
>
> as a starting point, first to understand how to proceed and then to
> check if what I did was correct.
>
> I verified almost everything except the Card Challenge, to be clear I
> would like to know how it is generated.
>
> As far a I know it should be generated as follows:
>
>  
>
> Card challenge (8 bytes) (with PRNG):
>
> AES-CMAC (Key-ENC , 0x00 00 00 00 00 00 00 00 00 00 00 02 00 00 40 01
> || context)
>
> “context“: concat. of sequence counter (3 bytes) and AID of the
> application invoking the SecureChannel (5 to 16 bytes).
>
>  
>
> Starting from the information on the file
>
>  
>
> globalplatform/git/ci/master/tree/globalplatform/src/scp03Test.c
>
>  
>
> I assumed that:
>
>  1. Key-ENC = {0xF9, 0x95, 0xD0, 0xA0, 0x69, 0x33, 0x5C, 0x7D, 0xF4,
>     0x2E, 0x59, 0x03, 0x17, 0xFF, 0xEA, 0x6D};
>  2. Sequence counter = {0x00, 0x00, 0x15};
>  3. AID = {0xA0, 0x01, 0x00, 0x01, 0x51, 0x41, 0x43, 0x4C};
>
>  
>
> The result card challenge, present on the same file into the
>  “initializeUpdateResponse” is
>
>  
>
> Card Challenge = {0xC4, 0x09, 0x32, 0xA6, 0xFE, 0xFE, 0xAE, 0xB2};
>
>  
>
> First of all, is all this correct?
>
>  
>
> If yes,
>
>                                                                        
> | context
>
> (00000000000000000000000200004001000015A00100015141434C)
>
>  
>
> And the Key-ENC is
>
>  
>
> (F995D0A069335C7DF42E590317FFEA6D)
>
>  
>
> Where I am wrong or what I have forgot?
>
> Any help would be appreciated.
>
>  
>
> Thanks in advance
>
>  
>
> Kind Regards
>
> Agostino Sette
>
>  
>
>  
>
>
>
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