13b - Internet Security

Question 1

What are two purposes of the addition of the digital signature to a message?

Answer 1

• To authenticate/confirm identity of sender
• To detect if message has been tampered with/altered/changed

Question 2

What is the difference between Symmetric Key and Public Key encryption?

Answer 2

• Symmetric key encryption: the same key/process/algorithm is used for encrypting and decrypting
• Public Key encryption: a public key and a private key are used in combination; one to encrypt, the other to decrypt

Question 3

Why is a firewall needed if the school wants to connect to the Internet?

Answer 3

• To prevent unauthorized access to a private network
• To safeguard the school’s network against hackers
• To block internal access to specific external sites
• To block certain ranges of IP addresses
• To close ports

Question 4

List four measures that can be used to reduce the threat posed by viruses.

Answer 4

• Use Anti-Virus Software
• Implement a Firewall
• Use a Proxy Server
• Employ Spam Filters
• Use Web Filters
• Utilize Digital Certificates
• Use Digital Signatures/Checksums

Question 5

What is the key exchange problem in relation to a symmetric cipher?

Answer 5

How to pass the key from the sender to the receiver without it being intercepted securely

Question 6

What is a Virus?

Answer 6

Program that attaches itself to/conceals itself within another program/file; Self-replicating; Has malicious purpose

Question 7

Explain the difference between a virus and a worm.

Answer 7

• Worm duplicates by exploiting network security weaknesses
• Worm is standalone software
• Worm replicates without user action
• Virus copies itself by attaching to other files
• Virus conceals itself within another file
• Virus relies on user running program to replicate it