ib technology
Sector Trailer Block
The last block of each sector (Blocks 3, 7, 11, 15……59, 63 etc) is the Sector Trailer Block
which contains the two security Key codes (KeyA and KeyB) and the Access bits that define
how the data blocks can be accessed (Read/Write, Read or Write only, as data or Value blocks
and using which key). If KeyB is not used then the last 6 bytes of the Sector Trailer Block can
be used for general data storage. Byte 9 (last byte of Access bits) is not used and can also be
used for general storage. Note that the KeyA (and KeyB) value read back as logical 0’s to
ensure system security.
IT IS STRONGLY RECOMMENDED THAT THE KEY CODES AND THE ACCESS BITS
STORED ON THE MIFARE CARD ARE NOT CHANGED UNTIL THEIR OPERATION
IS FULLY UNDERSTOOD.
Sector Trailer Block
Byte:
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15
KeyB (optional)
KeyA (6 bytes)
Access Bits
KeyA and KeyB
The security Key codes are each six bytes long and for successful authentication and
read/write communication the RWD device would have to have one or both keys stored in its
internal memory as well (depending on Access Bit settings). To allow “out-of-the-box”
operation with new Mifare transponders and RWD devices, Transport Key values are pre-
loaded into the transponder memory and also into the RWD memory.
Transport Key values as defined by Infineon are:
KeyA:
0xFF FF FF FF FF FF
KeyB:
0xFF FF FF FF FF FF
Transport Key values as defined by Philips Semiconductors are:
KeyA: 0xA0 A1 A2 A3 A4 A5 KeyB: 0xB0 B1 B2 B3 B4 B5
These KeyA and KeyB values are stored as repeated pairs in the MicroRWD MF device as a
factory default.
If the user intends using other Mifare cards then they may have different transport keys
loaded so the user would have to use the STORE KEY command to load the particular Key
codes into the RWD memory first. Once correct communication is established then Keys and
Access bits can be changed on the card and RWD to suit the users final system requirements.
Access Bits
The access conditions for every data block and sector trailer are defined by three bits (C1, C2,
C3), which are stored in a specific non-inverted and inverted pattern in the sector trailer of the
particular sector. The access bits control the memory access rights using the secret KeyA and
KeyB codes. The access bits can be changed provided the relevant Key(s) is known and the
current access conditions allow this operation.
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