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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 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.
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