01-04-2020-Oxford_English_for_Infomation_Technology (1171844), страница 20
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A program that has apayload but does not have a reproduction routine isknown as a Trojan.Now read the whole text to find the answers to these questions.123456How are computer viruses like biological viruses?What is the effect of a virus patching the operating system?Why are some viruses designed to be loaded into memory?What examples of payload does the writer provide?What kind of programs do viruses often attach to?Match each virus routine to its function.RoutineFunction1misdirectionadoes the damage2reproductionbattaches a copy of itself to another program3triggerchides the presence of the code4payloadddecides when and how to activate the payload7 How does a Trojan differ from a virus?126UNIT 18 Data Security 1LANGUAGE WORKate or event occurs which makes thetrigger routine run.What is the relationship between theseactions?1 A date or event occurs.2 The trigger routine runs.3 The payload routine activates.4 The hard disk is wiped.Putting the events in sequence and using acausative verb.3 The trigger routine runs, which activatesthe payload routine.These events form part of a cause and effectchain.
We can describe the links betweeneach event in a number of ways:Using cause + to V or make + V.1Using a when clause.4When the trigger routine runs, the payloadroutine activates.A date or event occurs which causes thetrigger routine to run.Describe the effects of these viruses and other destructiveprograms.1logic bomb-examplea A dismissed employee's name is deleted from the company'spayroll.b A logic bomb is activated.c All payroll records are destroyed.2Form (Boot sector virus)a A certain date occurs.b A trigger routine is activated.c Keys beep when pressed and floppies are corrupted.3Beijing (Boot sector virus)a The operator starts up the computer for the one hundredand twenty-ninth time.b A trigger routine is activated.c The screen displays, 'Bloody! June 4,1989'.4AntiEXEabcdThe infected program is run.The boot sector is corrupted.The disk content is overwritten.Data is lost.UNIT 18Data Security 1 1275Cascade (File virus - COM files only)a A particular date occurs.b The payload is triggered.c Characters on a text mode screen slide down to the bottom.6macro virus-examplea An infected document is opened in the word processor.b The virus macro is executed.c The virus code is attached to the default template.d The user saves another document.e The virus code attaches to the saved document.f The saved document is opened in the wordprocessor.g The virus destroys data, displays a message or plays music.Some verbs beginning or ending with en have a causativemeaning.
Replace the words in italics in these sentences with theappropriate form of en verb from this list.enableencodeencourageencryptenhanceenlargeensurebrightenwiden1A MIDI message makes sound into code as 8-bit bytes of digitalinformation.2The teacher is using a new program to give courage to childrento write stories.3The new version of SimCity has been made better in manyways.4A gateway makes it possible for dissimilar networks tocommunicate.5You can convert data to secret code to make it secure.6Make sure the machine is disconnected before you remove thecase.7Designers can offer good ideas for making your websitebrighter.8Electronic readers allow you to make the print size larger.9Programmers write software which makes the computer able tocarry out particular tasks.10You can make the picture on your monitor wider.128UNIT 18 Data Security 1PROBLEM-SOLVINGDecide in your group what these kinds of computer crime are.Then match the crimes to the short descriptions which follow.12345678910Salami ShavingDenial of Service attackTrojan HorseTrapdoorsMail bombingSoftware PiracyPiggybackingSpoofingDefacingHijackingaLeaving, within a completed program, an illicit program thatallows unauthorised - and unknown - entry.bUsing another person's identification code or using that person'sfiles before he or she has logged off.cAdding concealed instructions to a computer program so that itwill still work but will also perform prohibited duties.
In otherwords, it appears to do something useful but actually doessomething destructive in the background.dTricking a user into revealing confidential information such as anaccess code or a credit-card number.eInundating an email address with thousands of messages,thereby slowing or even crashing the server.fManipulating programs or data so that small amounts of moneyare deducted from a large number of transactions or accountsand accumulated elsewhere. The victims are often unaware ofthe crime because the amount taken from any individual is sosmall.gUnauthorised copying of a program for sale or distributing toother users.hSwamping a server with large numbers of requests.iRedirecting anyone trying to visit a certain site elsewhere.jChanging the information shown on another person's website.UNIT 18 Data Security 1SPEAKINGWork in pairs, A and B.
You both have details of a recentcomputer crime. Find out from your partner how his/her crimeoperated and its effects. Take notes of each stage in the process.Student AStudent BWRITING129Your computer crime is on page 187.Your computer crime is on page 193.Using your notes from Task 9, write an explanation of thecomputer crime described by your partner. When you have finished,compare your explanation with your partner's details on page 187 or193.WHEN YOU HAVE FINISHED THE READING SECTION ON THE FOLLOWING PAGES,COME BACK TO THESE ADDITIONAL EXERCISES3 Mark each of the following statements withTrue or False:4 Put the following sentences, about sendinga secure email, in the correct order:aabcdefghA message encrypted with a public key canbe decrypted by anyone.To send a secure message you must knowthe recipient's public key.Secure messages are normally encryptedusing a private key before they are sent.A message can be reconstructed from itsMAC.Two message can often have the same MAC.A digital certificate is sent to a client in anencrypted form.A digital certificate should be signed by atrusted digital-certificate issuer.A MAC is used to check that a message hasnot been tampered with.The message is decrypted with therecipient's private key.b The message is received by the recipient.c The message is encrypted with therecipient's public key.d The message is sent by the sender.130UNIT 18 Data Security 1Safe Data TransferSPECIALIST READINGBFlnd the answers to these questions in thefollowing text.1What does data encryption provide?a privacyb integrityc authenticationA message encrypted with the recipient'spublic key can only be decrypted witha the sender's private keyb the sender's public keyc the recipient's private keyWhat system is commonly used forencryption?What is the opposite of 'encrypt'?A message-digest function is used to:a authenticate a userb create a MACc encrypt a messageWhat information does a digital certificategive to a client?23456Secure transactions across the Internet havethree goals.
First, the two parties engaging in atransaction (say, an email or a businesspurchase) don't want a third party to be able toread their transmission. Some form of dataencryption is necessary to prevent this. Second,the receiver of the message should be able todetect whether someone has tampered with it intransit. This calls for a message-integrityscheme. Finally, both parties must know thatthey're communicating with each other, not animpostor. This is done with user authentication.Today's data encryption methods rely on atechnique called public-key cryptography.Everyone using a public-key system has a publickey and a private key. Messages are encryptedand decrypted with these keys.
A messageencrypted with your public key can only bedecrypted by a system that knows your privatekey.For the system to work, two parties engaging ina secure transaction must know each other'spublic keys. Private keys, however, are closelyguarded secrets known only to their owners.When I want to send you an encrypted message,This shows the complex process that's required to send datasecurely across open communication lines while satisfying thePublicSenderMessagedigestfunctionthree basic tenets of secure transfer: data encryption,interference prevention, and user authentification.Messageauthenticationcode1 The sender takes a document and produces a messageauthentication code (MAC) using a message-digest function.3 The sender attaches the encrypted MAC to the documentand encrypts both with the recipient's public key.2 The senderencrypts the MACwith their private key.4 When the recipient receives the document,they can decrypt it with their private key.Sender5 The recipient produces a local copy of the document's MACusing the same message-digest function the sender used.RecipientRecipient6 The recipient decrypts the sender'sMAC using the sender's public key.7 The recipient compares its local copy of the MAC to thesender's unencrypted MAC.
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