H1W200102 Datasheet, PDF (8/10 Pages) rfsolutions.ltd – Micro RWD H1 “Wiegand” Output Version

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Start of authorised tag codes. List is terminated with FF FF FF FF sequence.
List is regarded as empty (all identity codes valid) if first code sequence in list is (FF FF FF FF).
Byte 12: 0xFF
Byte 13: 0xFF
Byte 14: 0xFF
Byte 15: 0xFF
Empty list
Byte 16: (MSB) Tag identity code
Byte 17:
Byte 18:
Byte 19: (LSB)
Byte 20: (MSB) Tag identity code
Byte 21:
Byte 22:
Byte 23: (LSB)
-
-
Byte 127:
Last Internal EEPROM location
Encryption Methodology
The Micro RWD H1 has a data encryption system that allows data to be stored in an encoded
form that cannot be read as sensible data by any other Hitag 1 reader system.
On early versions of the Micro RWD (pre Ver. 1.20), data could be stored in the lower half of
the transponder memory (from page 16) as plain data with no encryption applied and stored in
the upper half (from page 32) in an encrypted form. The user could therefore choose the data
storage area according to security requirements. From version 1.20 onwards the form of the
stored data for the whole transponder memory (apart from the serial number, configuration
and other data in blocks 0-3) is controlled by the Encryption Control byte in the Micro RWD
internal EEPROM. If Encryption Control ON is selected then all data stored in the
transponder from page 16 upwards will be encrypted, and if OFF is selected then all data is
stored in standard format.
The method of encryption is unique and uses a “dynamic algorithm” which effectively makes
the encoded data specific to a particular transponder and a set of encryption seed values stored
in the Micro RWD internal EEPROM. This not only protects stored information but also
prevents cloning of cards or copying of data. Information is encrypted when being stored and
decrypted when being read, thereby making the process totally transparent to the user.
Another Hitag 1 reader system would read encrypted data as random bytes with no meaning.
Users should program their own encryption seed values to fully customise their system.
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