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There are many choices of
reader and credential technology available. There
is no ideal solution for all buildings, but each
system needs to decide what is the best choice for
them.
Factors
Readers
Wiegand
Factors
Credential uniqueness
All access control systems
rely upon being able to uniquely identify a user.
Many systems offer a totally unique credential
number. If a credential is available from multiple
suppliers, then it is possible to have duplicate
identification.
26 bit Wiegand should be given
special mention. It uses only 8 bits for a site
code. This means that there are only 256 site codes
available. With most buildings then starting their
card numbering at zero, there are duplicate card
numbers in distribution. A similar analogy would be
of the car industry historically with a set number
of combinations for their cars.
Reproducibility
Since access control systems
rely upon unique credentials, the ability to
duplicate a credential undermines the security of
the device. The harder it is to copy a credential,
the more secure it is. Bar codes (without extra
protection) can be photocopied, PINs can be
remembered, etc. Biometrics have the advantage of
relying upon individual characteristics.
Durability
A good credential and reader
must be able to survive their environment. This
could have to include the occasional soaking, times
of heat, sun, cold, knocks and drops. Mechanical
devices are more prone to wear.
Size
This impacts on their ease of
use, as well as being carried. Credentials that can
fit on a key ring are less likely to be forgotten,
but don't support photo ID. This is one area where
it is impossible to please everyone. The size of the
reader determines how discrete or obvious it will
be.
Vandal proof
The readers need to be able to
withstand the occasional disgruntled visitor, or the
passing drunk.
Cost
The cheaper the better!
Side effects
Magnetic based credentials
have the side effect of either wiping other magnetic
devices, or being wiped by magnetic fields. Any
system relying upon permanent magnets should be
avoided.
Reader
Types
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Silicon Key
("iKey"):
A "contact
prox" key that provides a truly unique
key number making it totally secure. Its small
size makes it very easy to carry on a key ring
and is very rarely left at home. It is
resistant to water, heat, cold, magnetic
fields, two-year-olds, and general wear and
tear.
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Proximity Cards
("Prox")
A popular solution
because of its non-contact requirements, it
provides a convenient method to identify
users. It is possible to combine the card with
a photo but the cards unevenness often makes
this task difficult. The range is improving
but is still relatively close to the reader.
Just don't leave it in your pocket.
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Magnetic swipe
Cards ("Mag stripe")
An oldie but a cheapie.
These are a very common credential especially
where large quantities are required. Credit
cards, bank cards and the like are all mag
stripe. Their strength is in their low price
and cheap reader. They are unfortunately prone
to wear and tear and can be demagnetized
easily. Also, don't leave them in the sun.
They do, however, allow for photo ID very
easily.
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Personal
Identification Number ("PIN")
PINs provide a very
cheap solution for simple access control. It
is, however, incredibly insecure. PINs are
easily duplicated (anyone can remember a
number) and are often written down and left on
a desk.
A scrambling key pad
provides a much harder to copy PIN. Its
viewing angle is restricted to only those
people immediately infront, and the random key
positions stop people from copying key
locations. They are still prone to people
writing the PINs down, and for copying by word
of mouth.
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Smartcards
Many different types of
smartcards are available. They offer high
security but there are many different
standards and it is difficult to support them
all. Currently CS Technologies equipment
supports Absec smartcards and the Telstra TAFE
Chipper card. A great idea for access control
where the cards are already in place.
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Permanent Magnets
A number of older
systems use permanent magnets embedded into a
"key". They have the advantage of
being long lasting, but have a number of
shortcomings. The worst is that they can wipe
any magnetic media including your credit cards
and floppy disks. We strongly recommend
that permanent magnets be avoided.
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Biometrics
Biometrics is the use of
body parts (eg fingerprint or retina) to prove
a person's identity. It is incredibly secure
but often too expensive for most applications.
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Mechanical lock
Very cheap initially,
but costs quickly mount if previous users are
to be locked out. Keys can be duplicated, and
locks take time to change. No history
available.
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Silkey
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Prox
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Mag
stripe
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PIN
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Radio
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Biometrics
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Mechanical
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Number
of unique users
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Practically
infinite
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Limited
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Limited
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Number
of digits (typically 9999 or 999999)
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Limited
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Infinite
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Depends
on key type
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Site
code
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No
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Yes
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Yes
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No
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No
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No
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No
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Photo
ID
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No
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Almost
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Yes
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No
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No
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No
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No
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Durability
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Exceptionally
good
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Reasonable
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Reasonable
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N/A
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Good
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Exceptionally
Good
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Exceptionally
Good
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Resistant
to Magnetic fields
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Yes
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Yes
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No
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N/A
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Yes
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Yes
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Yes
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Hard
to duplicate
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Yes
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Yes
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No
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No
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No
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Definitely
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No
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Reader
price
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Very
cheap
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Reasonable
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Cheap
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Cheap
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Reasonable
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Very
expensive
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Cheap
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Credential
price
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Moderate
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Moderate
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Cheap
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Free
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Reasonable
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Free
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Moderate
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Carry
convenience
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Very
(key ring/pocket)
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Reasonable
(clip on pocket)
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Reasonable
(clip on pocket)
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N/A
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Very
(key ring/pocket)
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N/A
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Very
(key ring/pocket)
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Ease of use
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Good
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Very
easy
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Reasonable
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Varies
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Very
easy
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Varies
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Reasonable
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Ease of
disabled use
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Reasonable
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Very
good
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Poor
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Poor
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Good
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Varies
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Very
poor
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What
is Wiegand?
Wiegand was initially used
within swipe cards. It has now become a de-facto
standard for many readers. This then means that a
site does not have to be locked into one supplier
for their readers and controllers. They can choose
what type of reader they require, and then which
company will install and service the system
(including controllers).
There are currently a number
of versions of Wiegand. They vary in how many bits
of information are stored. The more, the better.
Initially, only 256 site codes
were available. There are more than 256 sites in the
world and many of them have duplicated site codes.
It is conceivably possible for a person from one
site to enter another site. This same format is
still available today. Be careful!
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