using my Proxmark I'm able to retrieve the keys, dump the card, hex dump the dump and do a diff to compare what changed between the usage of the card.
so now I'm in the point that I must reverse engineer the information stored in the card
There is any common pattern used in the market to organize the data in the card like, is it normally encoded somehow? Reading some specs i found that some cards use BER-TLV, is that right? Any one with experience in this area and that want to share your experience/give some tips?
Every end-user is able to do their own use of the cards. Try to read about OV-chip and similar published projects. They open your mind .