Computer Security Questions and Answers

Answer: A

Correct answer: Message Nonrepudiation

Nonrepudiation means the sender cannot later deny having sent the message. A digital signature provides it, because only the sender's private key could have produced the signature.

Answer: A

Correct answer: Message authentication code

A MAC is a hash computed with a secret key, so it proves both that the message is unaltered and that it came from someone holding the key - integrity and authentication together.

Answer: B

Correct answer: Computer Virus

Self-replication is the defining property of a virus: it copies itself into other programs, and those copies spread when the host programs are run or shared. A pen drive can carry a virus but does not replicate anything itself.

Answer: A

Correct answer: Lock the computer with a password

Locking the session requires the password to be re-entered before anything can be reached, so it protects the data. A screen saver only hides the screen and turning off the monitor only darkens it - in both cases everything remains open to anyone who touches the keyboard.

Answer: D

Correct answer: None of the above

A firewall is a protective measure, not a threat: it filters connections to and from a machine. It is neither a virus, nor a worm, nor a security threat of any kind, so none of the three categories fits.

Answer: A

Correct answer: macro

A macro virus lives in the macro language of a document rather than in an executable, so it travels wherever documents travel - which in practice means email, freely and among very large numbers of users. It is also platform independent for the same reason, since it needs only the application, not the operating system.

Answer: D

Correct answer: Code Red

Code Red was a worm that spread through Microsoft IIS web servers in 2001. AVG, Avast and McAfee are all antivirus products, which makes Code Red the odd one out.

Answer: C

Correct answer: Receiver site

Encryption happens where the message originates and decryption where it is read, so the message is in ciphertext for the whole of its journey. That is what protects it in transit.

Answer: A

Correct answer: Bomb

A payload that waits for a condition before acting is called a bomb - a time bomb when the trigger is a date, a logic bomb when it is some other event. The delay is what the name refers to.

Answer: D

Correct answer: Asymmetric-Key

In an asymmetric system the sender encrypts with the receiver's public key, so only the holder of the matching private key can read the message. That gives confidentiality without the two parties ever having shared a secret in advance.