A session symmetric key between two parties is used
Answer: A
Correct answer: Only once
A session key is generated for a single exchange and discarded afterwards. Using it once limits the amount of ciphertext produced under any one key and means that a key compromised later cannot decrypt earlier traffic.
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Encryption and decryption provide secrecy, or confidentiality, but not
Answer: B
Correct answer: Integrity
Encryption hides the content but does not protect it from alteration: an attacker who cannot read the ciphertext may still change bits in it, and the receiver would decrypt something different without knowing. Integrity therefore needs a hash or a MAC in addition to the encryption.
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When data must arrive at receiver exactly as they were sent, its called
Answer: B
Correct answer: Message Integrity
Integrity is the guarantee that the message arrives exactly as it was sent, with no bit altered. Confidentiality is a separate guarantee, that nobody else can read it.
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Firewalls are used to protect against --------
Answer: C
Correct answer: unauthorised access
A firewall controls which connections may be made to and from a machine, so what it prevents is access by people and programs that have no business there. It does not inspect files for viruses, which is a separate job.
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A portion of the Polymorphic virus, generally called a …………………….. , creates, a random encryption, key to encrypt the remainder of the virus.
Answer: D
Correct answer: mutation engine
The part of a polymorphic virus that generates the random key and rewrites the encrypted body is called the mutation engine. The other three names are not used.
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The type(s) of auto executing macros, in Microsoft word is/are
Answer: D
Correct answer: All of the above
Word supports all three kinds: command macros that replace a built-in command and run when it is invoked, auto macros that run on events such as opening or closing a document, and the AutoExec macro that runs when Word itself starts. Each gives a macro virus a way to execute without the user choosing to run anything.
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The altering of data so that it is not usable unless the changes are undone is
Answer: B
Correct answer: encryption
Encryption transforms data by a reversible algorithm so that it is unreadable without the key, and readable again once the transformation is undone. Compression also alters data reversibly but its purpose is to reduce size, not to conceal; biometrics identifies people and ergonomics concerns workplace design.
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Select the correct order for the different phases of virus execution. i) Propagation phase ii) Dormant phase iii) Execution phase iv) Triggering phase
Answer: A
Correct answer: ii, i, iv and iii
A virus passes through four phases in order: it lies dormant after infection, then propagates copies of itself into other programs, then is triggered by some event, and only then executes its payload. Spreading before acting is what makes a virus dangerous, so propagation must precede execution.
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Which of the following is known as Malicious software?
Answer: D
Correct answer: malware
Malware is the contraction of malicious software, and it covers viruses, worms, trojans, spyware and ransomware alike. The other three words are not terms in use.
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Message confidentiality or privacy means that sender and receiver expect
Answer: B
Correct answer: Confidentiality
Confidentiality, or privacy, is exactly the expectation that nobody but the intended receiver can read the message. Integrity, authentication and nonrepudiation are the other three services and answer different questions.
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