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snaak

Contributor

Registered: 2019-08-11

Posts: 2

Need help analyzing hex data

Hello everyone,

About a week back I was in a hotel with my family and managed to get four cards back home. Two of the cards are for room 418 and the other two are for room 419. Our checkout date was the 9th of August.

For fun I dumped the card's data and tried analyzing the hex data to see if I could find a pattern. Unfortunately I couldn't find such a pattern. Here is the hex data for all the cards: (I only included sector 1, since that was the only sector with data on it)

418:
UID = 23 2A 1D 27
data   : 4D B2 00 00 00 00 00 00 00 00 00 00 00 00 00 00           
data   : 00 20 13 C1 82 00 0F F0 70 03 06 10 56 E4 59 00           
data   : 0A 29 9B DF 53 3B 8E 00 00 00 00 00 00 00 00 00           
trailer: 00 00 00 00 00 00 FF 07 80 69 8A 19 D4 0C F2 B5

418:
UID = 01 26 1D F9
data   : 4D B2 00 00 00 00 00 00 00 00 00 00 00 00 00 00           
data   : 00 20 13 C1 82 00 0F F0 E0 99 80 BF BA 34 2A 00           
data   : 1B 94 41 9B C0 0A 72 00 00 00 00 00 00 00 00 00           
trailer: 00 00 00 00 00 00 FF 07 80 69 8A 19 D4 0C F2 B5

419:
UID = D5 A4 2A 2C
data   : 4D B2 00 00 00 00 00 00 00 00 00 00 00 00 00 00           
data   : 00 20 13 C1 82 00 0F F1 28 DA 4E 4D 9D 80 EF 00           
data   : 55 1D 95 40 8F FD E2 00 00 00 00 00 00 00 00 00           
trailer: 00 00 00 00 00 00 FF 07 80 69 8A 19 D4 0C F2 B5

419:
UID = F3 B0 29 26
data   : 4D B2 00 00 00 00 00 00 00 00 00 00 00 00 00 00           
data   : 00 20 13 C1 82 00 0F F0 1B 22 55 AC 14 D3 DA 00           
data   : 17 72 4B 8F A7 28 FC 00 00 00 00 00 00 00 00 00           
trailer: 00 00 00 00 00 00 FF 07 80 69 8A 19 D4 0C F2 B5

Key A/B = 8069 8A19 D40C F2B5 (block 1, rest is FFFF FFFF FFFF FFFF)
Access bits = FF 07 80 69

The cards are Mifare Classic 1K. It is possible that I overlooked something, but it is also possible that access control in the hotel was done using some sort of central server that communicates with all the readers.

Thanks in advance

- Roel

Arjano

Contributor

Registered: 2020-01-18

Posts: 2

Re: Need help analyzing hex data

Hi Roel,

I stayed in a hotel with similar keys. I recognize the hex patterns. I also noticed the UID of the cards were not important. Copying the data to a card with a different GUI still worked. So either there is an algorithm in the door card readers, or there is a connecting to a central system, however since I was staying at a 3-star hotel, is unlikely.

So it would be hard to "crack the code", based on only a few card dumps.

iceman

Administrator

Registered: 2013-04-25

Posts: 9,537

Website

Re: Need help analyzing hex data

when it comes to hotel systems,  try log the date / time for your visit.  See if you can spot that data from the card data.