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Bar
Code
A barcode is a series of alternating dark and light
stripes that are read by an optical scanner. The organization and width
of the lines is determined by the bar code protocol selected. There are
many different protocols but Code 39 is the most popular in the
security industry. Sometimes the digits represented by the dark and
light bars are also printed to allow people to read the number without
an optical reader. The advantage of using bar code technology is that
it is cheap and easy to generate the credential and it can easily be
applied to cards or other items. The disadvantage of this technology is
that it is cheap and easy to generate a credential making the
technology susceptible to fraud and the optical reader can have
reliability problems with dirty or smudged credentials. One attempt to
reduce fraud is to print the bar code using carbon-based ink and then
cover the bar code with a dark red overlay. The bar code can then be
read with an optical reader tuned to the infrared spectrum, but can not
easily be copied by a copy machine. This does not address the ease with
which bar code numbers can be generated from a computer using almost
any printer.
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Magnetic
Stripe
Magnetic stripe technology, usually called mag-stripe,
is so named because of the stripe of magnetic oxide tape that is
laminated on a card. There are three tracks of data on the magnetic
stripe. Typically the data on each of the tracks follows a specific
encoding standard, but it is possible to encode any format on any
track. A mag-stripe card is cheap compared to other card technologies
and is easy to program. The magnetic stripe holds more data than a bar
code can in the same space. While a mag-stripe is more difficult to
generate than a bar code, the technology for reading and encoding data
on a mag-stripe is widespread and easy to acquire. Magnetic stripe
technology is also susceptible to misreads, card wear, and data
corruption.
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Key Pad - Pin
A personal identification number (PIN) falls in the
category of what you know rather than what you have. The PIN is usually
a number consisting of four to eight digits. Less and the number is too
easy to guess. More and the number is too difficult to remember. The
advantage to using a PIN as an access credential is that once the
number is memorized, the credential cannot be lost or left somewhere.
The disadvantage is the difficulty some people have in remembering
numbers that are not frequently used and the ease with which a PIN can
be observed and therefore used by unauthorized people. The PIN is even
less secure than a bar code or magnetic stripe card.
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Biometric
There are several forms of biometric
identification employed in access control: fingerprint,
hand geometry, iris and face recognition. The use of biometric
technology significantly increases security level of systems because it
eliminates such problems as lost, stolen or loaned ID cards, and
forgotten or guessed PINs. The operation of all biometric readers is
alike: they compare the template stored in memory to the scan obtained
during the process of identification. If the probability that the
template in the memory and the live scan belong to the same person is
high enough, the ID number of that person is sent to a control panel.
The control panel then checks permissions of the user and makes the
decision whether to grant access or not. The communication between the
reader and the control panel is usually done in the industry standard
Wiegand protocol. The only exception is intelligent biometric readers
that do not require any panels and directly control all door hardware.
Biometric templates may be stored in the memory of
readers, in which case the number of users is limited by reader memory
size. Readers currently available in the market may store up to 50,000
templates. Template of each user may also be stored in the memory of
his/her smart card. This option removes all limits to the number of
system users, but it requires each user to have a card and makes
finger-only identification impossible. Biometric templates may also be
stored in the memory of a central server PC. This option is called
"server-based verification". Readers simply read biometric data of
users and forward it to the main computer for processing. Such systems
support large number of users, but they are very much dependent on the
reliability of the central server and communication lines.
1-to-1 and 1-to-many are the two possible modes of
operation of a biometric reader.
- In the 1-to-1 mode a user must
first identify himself/herself to the reader by either presenting an ID
card or entering a PIN. The reader then looks up the template of the
user in the database and compares it with the live scan. The 1-to-1
method is considered more secure and is generally faster as the reader
needs to perform only one comparison. Most 1-to-1 biometric readers are
"dual-technology" readers: they either have a built-in proximity, smart
card or keypad reader, or they have an input for connecting an external
card reader.
- In the 1-to-many mode a user
presents his finger (or hand, eye, etc.) and reader needs to compare
the live scan to ALL the templates stored in the memory. This method is
preferred by most end-users, because it eliminates the need to carry ID
cards or use PINs. On the other hand this method is slower, because the
reader may have to perform thousands of comparison operations until it
finds the match. An important technical characteristic of 1-to-many
readers is the number of comparisons that can be performed in one
second, which is considered the maximum time that users can wait at a
door without noticing a delay. Currently most 1-to-many readers are
capable of performing 2000-3000 matching operations in one second.
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Proximity
Card
The Wiegand effect was used in early access cards. This
method was abandoned in favor of other technologies. Card readers are
still referred to as "Wiegand output readers" but no longer use the
Wiegand effect. The new technologies retained the Wiegand upstream data
so that the new readers were compatible with old systems. A Proximity
reader radiates a 1" to 20" electrical field around itself. Cards use a
simple LC circuit. When a card is presented to the reader, the reader's
electrical field excites a coil in the card. The coil charges a
capacitor and in turn powers an integrated circuit. The integrated
circuit outputs the card number to the coil which transmits it to the
reader.
A common proximity format is 26 bit Wiegand. This format
uses a facility code, sometimes also called a site code. The facility
code is a unique number common to all of the cards in a particular set.
The idea is that an organization will have their own facility code and
a set of numbered cards incrementing from 1. Another organization has a
different facility code and their card set also increments from 1. Thus
different organizations can have card sets with the same card numbers
but since the facility codes differ, the cards only work at one
organization. This idea worked fine for a while but there is no
governing body controlling card numbers, and different manufacturers
can supply cards with identical facility codes and identical card
numbers to different organizations. Thus there is a problem of
duplicate cards. To counteract this problem some manufacturers have
created formats beyond 26 bit Wiegand that they control and issue to
organizations.
In the 26 bit Wiegand format, bit 1 is an even parity
bit. Bits 2-9 are a facility code. Bits 10-25 are the card number. Bit
26 is an odd parity bit. Other formats have a similar structure of a
leading facility code followed by the card number and including parity
bits for error checking.
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Wiegand
Card
Wiegand card technology is a patented technology using
embedded ferromagnetic
wires strategically positioned to create a unique pattern that
generates the identification number. Like magnetic
stripe or bar code,
this card must be swiped through a reader to be read. Unlike those
other technologies the identification media is embedded in the card and
not susceptible to wear. This technology once gained popularity because
of the difficulty in duplicating the technology creating a high
perception of security. This technology is being replaced by proximity
cards because of the limited source of supply, the relatively better
tamper resistance of proximity readers, and the convenience of the
touch-less functionality in proximity readers.
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Smart
Card
There are two types of smart cards: contact and
contactless. Both have an embedded microprocessor and memory. The smart
card differs from the card typically called a proximity card in that
the microchip in the proximity card has only one function: to provide
the reader with the card’s identification number. The
processor on the smart card has an operating system and can handle
multiple applications such as a cash card, a pre-paid membership card,
and even an access control card. The difference between the two types
of smart cards is found in the manner with which the microprocessor on
the card communicates with the outside world. A contact smart card has
eight contacts, which must physically touch contacts on the reader to
convey information between them. Since contact cards must be inserted
into readers carefully and the orientation has be observed the speed
and convenience of such transaction is not acceptable for most access
control applications. The use of contact smart cards is physical access
control is limited mostly to parking applications when payment data is
stored in card memory and when the speed of transactions is not
important. A contactless smart card uses the same radio-based
technology as the proximity card with the exception of the frequency
band used: higher frequency (13.56Mhz instead of 125kHz) allows to
transferring more data and communicating with several cards at the same
time. A contactless card does not have to touch the reader or even be
taken out from a wallet or purse. Most access control systems only read
serial numbers of contactless smart cards and do not utilize the
available memory. Card memory may be used for storing biometric data
(i.e. fingerprint template) of a user. In such case a biometric reader
first reads the template on the card and then compares it to the finger
(hand, eye, etc.) presented by the user. This way biometric data of
users does not have to be distributed and stored in the memory of
controllers or readers, which simplifies the system and reduces memory
requirements.
Smartcard readers have been targeted successfully by
criminals in what is termed a supply chain attack, in which the readers
are tampered with during manufacture or in the supply chain before
delivery. The rogue devices capture customers' card details before
transmitting them to criminals.
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