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The
cards security community are well aware of the
added security afforded by a contact less smart
card and associated smart card readers but are
generally unaware of the potential weakness
in the level of security provided by most supposed
"smart card" readers including many
Mifare, Legic and other smart card versions.
Virtually all-current Mifare card access solutions
employ a combined antenna with associated electronics,
termed a card reader, which is then normally
connected via a signal cable to a separate controller.
The secure encrypted Mifare card data is detected
by the antenna and the required information
is then read from it. This secure information
is then decrypted into a legible chunk of data
by the reader. This is then sent to a door "access
controller" normally over a signal cable
using a security industry standard from the
seventies called “Wiegand”, which is a public
domain published open format.
The logic of providing a very secure interface
between card and reader head while maintaining
an unsecured connection between reader head
and controller is questionable, since it is
relatively easy, on the unprotected electrical
interface, to intercept the unprotected data
stream or inject false data into the data stream.
Indeed most card readers lack a simple tamper
sensor so that attempts to compromise or remove
the reader head will not be detected and affects
around 90% of the readers available in the marketpalce.
This compromises the high level of security
built around the card and card reading technology.
By combining the functions of antenna, card
reader decoder and controller into a single
unit, Borer has eliminated this compromise to
security. All information is exchanged at the
logical data level where it can be encoded and
if required encrypted. This eliminates the need
to pass secure data across an unsecured electrical
interface. Consequently, all communications
from the card to the central database are secure
and safeguarded from attack.
In a Borer access control application, the combined
Mifare reader controller is located on the unsecured
side of the door to prevent the door unlock
signal being tampered with. For added security,
the reader controller can be logically associated
with an IO device, which controls the operation
of the door, located on the secure side. This
can be a second card reader controller, providing
in and out control, or a logical IO unit.
Communications between the card reader controller
on the unsecured side of the door and the IO
controller on the secured side is across the
Controller Area Network (CAN) data link. This
solution maintains both signal and data integrity
Notes:
Wiegand is a two wire electrical interface,
first employed in the 1970’s, designed to enable
a card reader made by one manufacturer to pass
data read from a card to a controller produced
by a different manufacturer. It consists of
two wires called “Data-0” and “Data-1”. A short
pulse on the “Data-0” represents a binary “0”
while a pulse of the “Data-1” represents a binary
“1”.
With this basic understanding of how to translate
the information in the # bit Wiegand format,
you can apply a similar convention to decode
the data in any other data format passed over
a Wiegand interface. Once you know the distribution
of the data fields, you can extract the facility
code and user ID fields. Hence, it is self evident
that data read from a secure and encrypted smart
card, such as a MiFare or Desfire, when passed
across an unencrypted Wiegand interface is open
to skimming and manipulation.
Signals are electrical pulses
or levels passed along cables (e.g. digital
signals connecting the reader head to the controller
or analogue signals from the controller to the
lock and the door open sensor).
Data is the exchange of digitally
encoded information between devices (e.g. the
card and the central access control data base
via the reader controller
and connecting network).
Contactless Smart Card is typically
a "credit card" sized form factor
with a smallembedded microprocessor chip, which
can be programmed to perform tasks and store
information. There are different types of smart
cards: memory cards, processor cards, electronic
purse cards, security cards, and Java Cards.
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