hex - How is this data from a magnetic card encoded? -

i have information magnetic cards control building access, , need reverse engineer way software stores data on cards make more features. (we have lost contact original programmer.)

i have no idea how writing order done; i'm no magnetic card expert. know few things:

• data on third track.
• all readers standalone , have batteries.
• there master card can add or remove cards reader(currently, need go through doors add or remove card system).
• each card different, , must have unique identifier.
• there expiration date, have no idea if it's date format or number incrementing in door readers.
• there "flag" gives access special places (parking) , isn't affected expiration date... weird.

i've got reader , software read it. gives me hexadecimal numbers. example here few cards i've got.

1. bac716863b8cb32832babab40e1739bab677563b3af8ba3abababebabababababac0 (card parking)

2. bdc011813cb9b4cbb53dbdb21fd2bcbdbeea3ebdbdffbd3dbdbdb1bdbdbdbdbdbdc0 (card parking)

3. 9de031a11ca9912e951d9d9225369d1d9fce6c9d1ddf9d1d9d9d9d9d9d9d9d9d9dc0 (normal card, no special access)

i hope it's not secured make impossible reverse-engineer.

this question comes high on google, experienced similar issue , solved it.

data on magnetic card encoded in ansi/iso alpha data format (on track 1) , ansi/iso bcd data format (on track 2 , 3). magnetic card readers decode data before returning don't have reader don't , here are.

you can find encoding table , more information here: http://www.abacus21.com/magnetic-strip-encoding-1586.html