Proxmark3 community

nakbi

Member

Registered: 2010-03-03

Posts: 2

Mifare question

Hi people,

I am new here and also new to mifare technology.
I have a question:
I have a brand new mifare 1k card. When I try to read a sector trailer byte [for example 3B], I have to authenticate it with the KeyA as FF FF FF FF FF FF. When I try to read it, I get the 00 00 00 00 00 00 FF 07 80 69 FF FF FF FF FF FF .
From the stuff I studied I can see that the the first part [this one with the zeros] is the KeyA and the part with the FFs is the KeyB.
I thought that normally the KeyA is 000000000000 but it authenticates with the FFs.
But...
When I write in this block the same 16bytes I read, then it authenticates with the zeros.

Whas is happening? Can anyone please explain this to me?

Sorry if i confused you.
Thanks in advance.

rconty

Member

Registered: 2009-06-15

Posts: 7

Re: Mifare question

Whas is happening? Can anyone please explain this to me?

That's normal, KeyA could not be read, so 0x00 are sent by card instead of KeyA.
If you want to play with Mifare Classic, its strongly recommanded to read "MF1ICS50 Functional specification" from NXP to understand how Mifare Classic cards works.

nakbi

Member

Registered: 2010-03-03

Posts: 2

Re: Mifare question

Thanks rconty, now I understood.