Proxmark3 community

nock

Contributor

Registered: 2019-12-11

Posts: 15

Mifare "Serial" Number (CSN) - Not UID

Hi,

I have been trying to find a simple reader device to read the "serial" numbers of our Mifare Desfire cards that we use for a separate system to help with audit control and record keeping.

I have tried the Proxmark3 as well as a simple adjustable USB reader that supposedly can output the UID (or part of it) in different formats (eg 8 digit decimal, 10 digit decimal, hex etc).

But the UID (from Proxmark3) and all the output formats that the adjustable USB reader can read are different to the serial number displayed (CSN) in our other system.  As a second-best solution, can anyone please guide me on how to convert the UID to the serial number in the format that I require?  I was told something along the lines of that the reader is 32 bit and then the device reverses 26 or 28 bits?

As an example, I have a card that shows up in our system with a CSN: 274769

Here is the output from the Proxmark3:
UID : 04 31 51 a2 3a 5b 80
ATQA : 00 44
SAK : 20 [1]
TYPE : NXP MIFARE DESFire 4k | DESFire EV1 2k/4k/8k | Plus 2k/4k SL3 | JCOP 31/41
MANUFACTURER : NXP Semiconductors Germany
ATS : 0c 75 77 80 02 c1 05 2f 2f 01 bc d6 60 d3
       -  TL : length is 12 bytes
       -  T0 : TA1 is present, TB1 is present, TC1 is present, FSCI is 5 (FSC = 64)
       - TA1 : different divisors are supported, DR: [2, 4, 8], DS: [2, 4, 8]
       - TB1 : SFGI = 0 (SFGT = (not needed) 0/fc), FWI = 8 (FWT = 1048576/fc)
       - TC1 : NAD is NOT supported, CID is supported
       -  HB : c1 05 2f 2f 01 bc d6-> MIFARE Plus X 2K or 4K
               c1 -> Mifare or (multiple) virtual cards of various type
                  05 -> Length is 5 bytes
                     2x -> MIFARE Plus
                        2x -> Released
                           x1 -> VCS, VCSL, and SVC supported

And here is the different outputs from the simple reader with the different output options (eg 8 digit decimal, 10 digit decimal, hex etc):
10 Digit Output: 2723229956
8 Digit Output: 08112548
HEX Output: a2513104
Other Outputs:
12548
274769
513104
23229956
4155312548
0070341026
043151a2
05320964
0005320964
272322995608112548
88a2513104

mwalker

Moderator

Registered: 2019-05-11

Posts: 318

Re: Mifare "Serial" Number (CSN) - Not UID

As a very quick guess and based on a sample of 1.

From your post
CSN: 274769

Proxmark Shows UID : 04 31 51 a2 3a 5b 80

Take the first 3 bytes of the UID 043151 (which is in hex)
Convert to decimal : 274769 which is the same as your CSN.

iceman

Administrator

Registered: 2013-04-25

Posts: 9,537

Website

Re: Mifare "Serial" Number (CSN) - Not UID

If you add spaces to the HEX output vs the UID it becomes even clearer?

HEX Output: a2 51 31 04
UID 04 31 51 a2 3a 5b 80