bachelor

1.2 Technology and card layout 7
Figure 1.1: The Mifare memory layout. Figure by de Koning Gans et. al, used
with permission.
• Access control: 3 bytes. These bits define the access conditions for the
sector. See 1.2.3.3 for a list of functions these bytes govern access to.
• An unused byte.
• Key B: 6 bytes. This is the secondary key. It can have access control
separate to key A,
The first block of the first sector of every Mifare card is a little special; it is
burned into the card and cannot be changed, ever. It contains the manufacturer
data of the card, including the cards unique ID. For this reason sector 0 only
has only two writable blocks instead of three, see Figure 1.1.
1.2.3.3 Challenge/response
Mifare implements a challenge/response protocol that must be satisfied before
a terminal can log in to a card. The protocol is described in [3], and can be
described in plain text as seen in Figure 1.2.
After authenticating to the sector, the card provides the following actions, for
some given block in the sector: