Forum / MIFARE general topics and applications / DesfireEV1 Change the Default DES Key (all 0's) to AES
Tagged: Mifare Desfire EV1
everything is working on my side ,
i have one problem in changing the Default PICC Master Key from DES to AES (iam
stuck at this point from 5 days!!),, below is my logs : please take a look and let
me know what iam doing wrong
Res = AF5039C16807AB67FE
KEYNO= 80 (Aes)
Data To Decrypt=00000000000000000000000000000000C8B6000000000000
Decrypted Dta = 90133EAF84AA8BC5D9EEBA4BDD20CE93C97026E54C44738C
RES= 1E !!
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What I can see here is that you forget to include the KeyVersion into the data preparation before encryption. When updating a key from 2K3DES or 3K3DES to AES, the 16 bytes long key needs to be concatenated with the key version (which I guess is 00 in your case), the CRC16, and filled up with padding in order to reach a multiple of the blocksize.
The data to encrypt would look like this = 0000000000000000000000000000000000 C8B60000000000, so one more bytes of zeros needs to be added before the CRC16 and the padding.
Afterwards you need to encrypt it and send the command Cmd = C4 || encrypted data.
I hope with including the key version it is working for you.
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