Hi,
I know it's my old topic, but I have come back to it.
The complication is to understand Card formats and how to read the data. At the moment for example:
I have a Mifare Classic 4K card
the ACS system by default reads the first 32bit which is the Card Serial Numer (CSN)
The system is CEMsys AC2000
I know that I need to read different numbers, which are 8-digit number encoded in Sector-1 Block-2.
To read CSN in the card definition setting field of the AC2000
Start position - 1
My question is why is this not start from position - 0 ? As computers read from zero first? As otherwise then all pern doesn't match when counting bits? Or I'm wrong here?
Field length - 32
this is where I match my understanding against the CSN as I can read and match the first 32bits (4bytes) or hex value, in the screenshot line 92 of my text editor where I have selected the value.
So, if the block length is 128bit (per line), then my interesting data starts at the 6th line which is per block number [05] (text editor line 100) as it starts counting blocks from [00] in the sector [00]. This should mean that it should start read my interesting data from 641bit and the Field length should be 24bits (as 8 digit number fits in 3bytes https://www.rapidtables.com/convert/number/decimal-to-hex.html )
another question here is - if the 8-digit number is encoded in hex or it's just the same number but in numbers only? In other words to say, how the read data is interpreted? Or if the reader reads the CSN number and displays hext then my number also, should be displayed as simple as this?
We are talking about reading unencrypted data, as I was told I should read this dara simply when scanning the card.
So I have many unknowns in my head, which is why it is totally confusing. I need some guidance or tips. or anything.
The