Basic question re UID in the Manufacturer's Block

[Mike Vessey]

I'm trying to figure out my own apartment's Mifare classic card (1024 bytes, 4 byte UID) and am stuck.

Using Android's MCT tool I get a UID of 6F4845D5. However if I view the dump of Block 0 it shows a completely different UID. For any other card the UID in the dump is the same as what the UID tool shows.

Why would this be the case? The images are attached (both are the same card).

Many thanks for any help

---

+ 0  |  - 0

[TapLinx Support]

Hi Mike,

In an anti-collision sequence at the reader, a 4-byte UID card uses also random bytes. A 4-byte UID is not unique anymore due to the short range.

You can also get a MIFARE Classic EV1 with the option of random UID in the anti-collision sequence. The device's UID is stored in block 0. But you need to authenticate before to read the block.

Especially for security applications you should never rely on the UID. In most cases the UID is randomness to prevent any tracking.

The TapLinx team

---

+ 0  |  - 0

[Author]

Posts