Authentication failed

[dominikrein]

Hi,

I've got auth failed for my DESFire EV3 with AES encryption, not sure if this code has ever been tested against...
Had success with following changes. There were the wrong initialization vectors used for cbc, as these are always the last encrypted bytes, never the unencrypted.
Furthermore the Cipher-Object has to be initialized again after every use.

DESFire_DEF.py

def Decrypt(self, dataEnc):
        #todo assert on blocksize
        block = self.Cipher.decrypt(bytes(dataEnc))
        return list(bytearray(block))

def Encrypt(self, data):
        #todo assert on blocksize
        block = list(bytearray(self.Cipher.encrypt(bytes(data))))
        return block

DESFire.py

def authenticate(self, key_id, key, challenge = None):
       # [...]
        key.CiperInit()
        RndB = key.Decrypt(RndB_enc)
        key.IV = RndB_enc[-key.CipherBlocksize:]
        key.Cipher = AES.new(bytes(key.keyBytes), AES.MODE_CBC, bytes(key.IV))

       # [...]

        RndAB_enc = key.Encrypt(RndAB)
        key.IV = RndAB_enc[-key.CipherBlocksize:]
        key.Cipher = AES.new(bytes(key.keyBytes), AES.MODE_CBC, bytes(key.IV))

[soulsurfer4]

Hi patsys,

I can confirm, that the AES authentication does not work currently.
The Cipher must recreate like @dominikrein stated above.

regards,
soulsurfer