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Security In Computer Systems

 

About two hundred years before, the word "computer" started
to appear in the dictionary. Some people even didn't know
what is a computer. However, most of the people today not
just knowing what is a computer, but understand how to use
a computer. Therefore, computer become more and more
popular and important to our society. We can use computer
everywhere and they are very useful and helpful to our
life. The speed and accuracy of computer made people felt
confident and reliable. Therefore, many important
information or data are saved in the computer. Such as your
diary, the financial situation of a oil company or some
secret intelligence of the military department. A lot of
important information can be found in the memory of
computer. So, people may ask a question: Can we make sure
that the information in the computer is safe and nobody can
steal it from the memory of the computer? Physical hazard
is one of the causes of destroying the data in the
computer. For example, send a flood of coffee toward a
personal computer. The hard disk of the computer could be
endangered by the flood of coffee. Besides, human caretaker
of computer system can cause as much as harm as any
physical hazard. For example, a cashier in a bank can
transfer some money from one of his customer's account to
his own account. Nonetheless, the most dangerous thief are
not those who work with computer every day, but youthful
amateurs who experiment at night --- the hackers. The term
"hacker "may have originated at M.I.T. as students' jargon
for classmates who labored nights in the computer lab. In
the beginning, hackers are not so dangerous at all. They
just stole computer time from the university. However, in
the early 1980s, hackers became a group of criminals who
steal information from other peoples' computer. For
preventing the hackers and other criminals, people need to
set up a good security system to protect the data in the
computer. The most important thing is that we cannot allow
those hackers and criminals entering our computers. It
means that we need to design a lock to lock up all our data
or using identification to verify the identity of someone
seeking access to our computers. The most common method to
lock up the data is using a password system. Passwords are
a multi-user computer system's usual first line of defense
against hackers. We can use a combination of alphabetic and
number characters to form our own password. The longer the
password, the more possibilities a hacker's
password-guessing program must work through. However it is
difficult to remember a very long passwords. So people will
try to write the password down and it may immediately make
it a security risk. Furthermore, a high speed
password-guessing program can find out a password easily.
Therefore, it is not enough for a computer that just have a
password system to protect its data and memory. Besides
password system, a computer company may consider about the
security of its information centre. In the past, people
used locks and keys to limit access to secure areas.
However, keys can be stolen or copied easily. Therefore,
card-key are designed to prevent the situation above. Three
types of card-keys are commonly used by banks, computer
centers and government departments. Each of this card-keys
can employ an identifying number or password that is
encoded in the card itself, and all are produced by
techniques beyond the reach of the average computer
criminals. One of the three card-key is called watermark
magnetic. It was inspired by the watermarks on paper
currency. The card's magnetic strip have a 12-digit number
code and it cannot be copied. It can store about two
thousand bits in the magnetic strip. The other two cards
have the capability of storing thousands of times of data
in the magnetic strip. They are optical memory cards (OMCs)
and Smart cards. Both of them are always used in the
security system of computers. However, it is not enough for
just using password system and card-keys to protect the
memory in the computer. A computer system also need to have
a restricting program to verify the identity of the users.
Generally, identity can be established by something a
person knows, such as a password or something a person has,
such as a card-key. However, people are often forget their
passwords or lose their keys. A third method must be used.
It is using something a person has --- physical trait of a
human being. We can use a new technology called biometric
device to identify the person who wants to use your
computer. Biometric devices are instrument that perform
mathematical analyses of biological characteristics. For
example, voices, fingerprint and geometry of the hand can
be used for identification. Nowadays, many computer
centers, bank vaults, military installations and other
sensitive areas have considered to use biometric security
system. It is because the rate of mistaken acceptance of
outsiders and the rejection of authorized insiders is
extremely low. Individuality of vocal signature is one kind
of biometric security system. The main point of this system
is voice verification. The voice verifier described here is
a developmental system at American Telephone and Telegraph.
Only one thing that people need to do is repeating a
particular phrase several times. The computer would sample,
digitize and store what you said. After that, it will built
up a voice signature and make allowances for an
individual's characteristic variations. The theory of voice
verification is very simple. It is using the
characteristics of a voice: its acoustic strength. To
isolate personal characteristics within these fluctuations,
the computer breaks the sound into its component
frequencies and analyzes how they are distributed. If
someone wants to steal some information from your computer,
the person needs to have a same voice as you and it is
impossible. Besides using voices for identification, we
can use fingerprint to verify a person's identity because
no two fingerprints are exactly alike. In a fingerprint
verification system, the user places one finger on a glass
plate; light flashes inside the machine, reflects off the
fingerprint and is picked up by an optical scanner. The
scanner transmits the information to the computer for
analysis. After that, security experts can verify the
identity of that person by those information. Finally, the
last biometric security system is the geometry of the hand.
In that system, the computer system uses a sophisticated
scanning device to record the measurements of each person's
hand. With an overhead light shining down on the hand, a
sensor underneath the plate scans the fingers through the
glass slots, recording light intensity from the fingertips
to the webbing where the fingers join the palm. After
passing the investigation of the computer, people can use
the computer or retrieve data from the computer. Although a
lot of security system have invented in our world, they are
useless if people always think that stealing information is
not a serious crime. Therefore, people need to pay more
attention on computer crime and fight against those
hackers, instead of using a lot of computer security
systems to protect the computer.
 
Why do we need to protect our computers ? It is a question
which people always ask in 18th century. However, every
person knows the importance and useful of a computer
security system.
 
In 19th century, computer become more and more important
and helpful. You can input a large amount of information or
data in a small memory chip of a personal computer. The
hard disk of a computer system is liked a bank. It
contained a lot of costly material. Such as your diary, the
financial situation of a trading company or some secret
military information. Therefore, it just like hire some
security guards to protect the bank. A computer security
system can use to prevent the outflow of the information in
the national defense industry or the personal diary in your
computer. Nevertheless, there is the price that one might
expect to pay for the tool of security: equipment ranging
from locks on doors to computerized gate-keepers that stand
watch against hackers, special software that prevents
employees to steal the data from the company's computer.
The bill can range from hundreds of dollars to many
millions, depending on the degree of assurance sought.
Although it needs to spend a lot of money to create a
computer security system, it worth to make it. It is
because the data in a computer can be easily erased or
destroyed by a lot of kind of hazards. For example, a power
supply problem or a fire accident can destroy all the data
in a computer company. In 1987, a computer centre inside
the Pentagon, the US military's sprawling head quarters
near Washington, DC., a 300-Watt light bulb once was left
burning inside a vault where computer tapes were stored.
After a time, the bulb had generated so much heat that the
ceiling began to smelt. When the door was opened, air
rushing into the room brought the fire to life. Before the
flames could be extinguished, they had spread consume three
computer systems worth a total of $6.3 million. Besides
those accidental hazards, human is a great cause of the
outflows of data from the computer. There have two kind of
people can go in the security system and steal the data
from it. One is those trusted employee who is designed to
let in the computer system, such as programmers, operators
or managers. Another kind is those youth amateurs who
experiment at night ----the hackers. Let's talk about those
trusted workers. They are the groups who can easily become
a criminal directly or indirectly. They may steal the
information in the system and sell it to someone else for a
great profit. In another hand, they may be bribed by
someone who want to steal the data. It is because it may
cost a criminal far less in time and money to bride a
disloyal employee to crack the security system. Beside
those disloyal workers, hacker is also very dangerous. The
term "hacker" is originated at M.I.T. as students' jargon
for classmates who doing computer lab in the night. In the
beginning, hackers are not so dangerous at all. They just
stole some hints for the test in the university. However,
in early 1980s, hacker became a group of criminal who steal
information from other commercial companies or government
departments.
 
What can we use to protect the computer ?
 
 We have talked about the reasons of the use of computer
security system. But what kind of tools can we use to
protect the computer. The most common one is a password
system. Password are a multi-user computer system's which
usual used for the first line of defense against intrusion.
A password may be any combination of alphabetic and numeric
characters, to maximum lengths set by the e particular
system. Most system can accommodate passwords up to 40
characters. However, a long passwords can be easily forget.
So, people may write it down and it immediately make a
security risk. Some people may use their first name or a
significant word. With a dictionary of 2000 common names,
for instance, a experienced hacker can crack it within ten
minutes. Besides the password system, card-keys are also
commonly used. Each kind of card-keys can employ an
identifying number or password that is encoded in the card
itself, and all are produced by techniques beyond the reach
of the average computer criminal. Three types of card
usually used. They are magnetic watermark, Optical memory
card and Smart card. However, both of the tools can be
easily knew or stole by other people. Password are often
forgotten by the users and card-key can be copied or
stolen. Therefore, we need to have a higher level of
computer security system. Biometric device is the one which
have a safer protection for the computer. It can reduce the
probability of the mistaken acceptance of outsider to
extremely low. Biometric devices are instrument that
perform mathematical analyses of biological
characteristics. However, the time required to pass the
system should not be too long. Also, it should not give
inconvenience to the user. For example, the system require
people to remove their shoes and socks for footprint
verification. Individuality of vocal signature is one kind
of biometry security system. They are still in the
experimental stage, reliable computer systems for voice
verification would be useful for both on-site and remote
user identification. The voice verifier described here is
invented by the developmental system at American Telephone
and Telegraph. Enrollment would require the user to repeat
a particular phrase several times. The computer would
sample, digitize and store each reading of the phrase and
then, from the data, build a voice signature that would
make allowances for an individual's characteristic
variations. Another biometric device is a device which can
measuring the act of writing. The device included a
biometric pen and a sensor pad. The pen can converts a
signature into a set of three electrical signals by one
pressure sensor and two acceleration sensors. The pressure
sensor can change in the writer's downward pressure on the
pen point. The two acceleration sensor can measure the
vertical and horizontal movement. The third device which we
want to talk about is a device which can scan the pattern
in the eyes. This device is using an infrared beam which
can scan the retina in a circular path. The detector in the
eyepiece of the device can measure the intensity of the
light as it is reflected from different points. Because
blood vessels do not absorb and reflect the same quantities
of infrared as the surrounding tissue, the eyepiece sensor
records the vessels as an intricate dark pattern against a
lighter background. The device samples light intensity at
320 points around the path of the scan , producing a
digital profile of the vessel pattern. The enrollment can
take as little as 30 seconds and verification can be even
faster. Therefore, user can pass the system quickly and the
system can reject those hackers accurately. The last device
that we want to discuss is a device which can map the
intricacies of a fingerprint. In the verification system,
the user places one finger on a glass plate; light flashes
inside the machine ,reflect off the fingerprint and is
picked up by an optical scanner. The scanner transmits the
information to the computer for analysis. Although
scientist have invented many kind of computer security
systems, no combination of technologies promises
unbreakable security. Experts in the field agree that
someone with sufficient resources can crack almost any
computer defense. Therefore, the most important thing is
the conduct of the people. If everyone in this world have a
good conduct and behavior, there is no need to use any
complicated security system to protect the computer. 

 




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