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- 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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