Security 2

Computer Security
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.

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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.

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