Unit 3

    Scenario #1: The agent shuts down your computer. (Yes/No)
    Scenario #2: The agent breaks your ISP Connection. (Yes/No)
    Scenario #3: The agent breaks one 15110 website server. (Yes/No)
    Scenario #4: The agent corrupts a packet sent to your computer. (Yes/No)
    Scenario #5: The agent breaks one router. (Yes/No)
    Scenario #6: The agent breaks one DNS server. (Yes/No)
    

Solution:

Scenario #1: Success: Yes
    

Why: Your computer is the connection from you to all of the sites and the internet. Without your computer, you will not be able to access the 15110 website and you will need to repair it in order to regain the connection. Therefore, the agent will be successful in breaking your computer’s connection and your visit to the 15110 website (provided you don’t use your phone to go!)

Scenario #2: Success: Yes
    

Why: Your ISP is critical to establishing a two-way connection between you and the internet: 1) It sends the packets your computer distributes to the rest of the internet. 2) All response packets must go back through the ISP to reach your computer again. This makes the ISP a bottleneck to the rest of the internet, therefore, breaking the ISP connection would render you without a way to access the internet and by extension send packets to access the 15110 website.

Scenario #3: Success: No
    

Why: Usually, a company has multiple servers that can handle traffic to a website, therefore in the breakage of one server, the traffic will be rerouted to another server. Therefore, if the agent breaks one 15110 website server, another 15110 website server will provide you with the information needed to access the website. Critically, all 15110 website servers will need to go down by the agent for it to be successful (as no where else to reroute). Thus, the agent is not successful in breaking the connection between you and the 15110 website in this scenario. Woohoo!

Scenario #4: Success: No
    

Why: Before engaging with the packet, your computer has a checksum that checks whether the packet is corrupted. If the packet is corrupted, then your computer will send a request for new packets from the 15110 website. Therefore, by corrupting a singular packet, the agent is not successful in breaking the connection between you and the 15110 website in this scenario. Woohoo!

Scenario #5: Success: No
    

Why: Routers, which form the core part of the internet, are heavily decentralized and connected. This means that not one router controls all of the traffic of the internet and they can easily send the requests between the routers if something happens to an individual router. That’s exactly what happens here. If one of the routers goes down because of the agent, then the traffic is rerouted to another router. Therefore, the agent is not successful in breaking the connection between you and the 15110 website in this scenario. Woohoo!

Scenario #6: Success: No
    

Why: DNS Servers are numerous and spread across the world. This means that if something happens to one DNS server your request simply gets redirected to a functioning DNS Servers. Therefore, the agent is not successful in breaking the connection between you and the 15110 website in this scenario. Woohoo!

    1. Break all DNS servers in the world
    2. Break all routers in the world
    3. Break all servers for 15110 website
    

Solution:

• #1. No, the agent cannot feasibly break all DNS servers. DNS servers are decentralized and are numerous in the world. Thus, even if some DNS servers are impaired, there are other DNS servers that your requests can be sent to. (no really, unless the agent has a superpower that can take down every DNS server in the world electrically this will not happen).
• #2. No, the agent cannot feasibly break all routers. Like DNS servers, DNS servers are decentralized and heavily connected, in which traffic that is disrupted can be sent to another router. (the agent would need a similar superpower to part 1).
• #3. Yes. The agent could feasibly take down all the servers associated with the 15110 website. Unlike DNS servers and routers, while there are multiple servers that could host websites like 15110, it is still possible to take out all these servers as it is not spread out or in high numbers like DNS servers or routers.

Solution: D

Solution (just examples, there are many correct answers!):

DDOS: A hacker writes code that repeatedly places orders to a business’ website, causing the website to crash for all users.
Man in the Middle: Someone sets up a fake router at Hunt Library and intercepts all patrons’ personal information like logins and passwords.

Solution:

• You visit a course Canvas page using HTTPS, log in with your password, and safely download a homework assignment -> None
• You try to log into an online game for a tournament, but the game server is flooded with fake traffic from thousands of hacked computers -> DDOS
• You attempt to connect to a coffee shop network called "FreeCafeWifi", but it is operated by a hacker who intercepts your credentials -> Man in the Middle

Solution:

1. “Unyyxgzwlm”

Below is how we reached this answer:
2. “Kizvmoqm Umttwv”
3. “Gdkkn Vnqkc”

Solution:

1. “Pennsylvania”

Below is how we reached this answer:
2. “University”
3. “It’s me!”

• If an algorithm is symmetric; that means that there is a shared key that needs to be known by both parties before messages can be exchanged.
• On the other hand, in a(n) asymmetric algorithm, parties have their own keys.

1. Caesar Cipher is a symmetric encryption algorithm.
2. RSA is an asymmetric encryption algorithm.

Solution:

D: Kelly uses Franceska's public key to encrypt the message and Franceska uses Franceska's private key to decrypt the message.

Solution (answers may vary):

RSA is more secure because the keys generated are huge prime numbers, which are very difficult to guess (via bruteforce algorithm) and therefore make decrypting a solution or message very difficult.

RSA is considered secure because it relies on the mathematical difficulty of factoring the product of two very large prime numbers. Currently, there is no known polynomial-time algorithm to solve this on a classical computer, making it significantly more secure than the Caesar Cipher.

The Caesar Cipher is breakable in constant time with respect to key search (finding the key for encoding/decoding, there are only 26 possible shift values to try in total), and linear time with respect to message length.

Solution (answers may vary):

The Caesar Cipher runs in polynomial time, as there are only 26 total possibilities to check in the worst-case scenario.

On the other hand, RSA is an NP problem because it involves mathematical operations on very large prime numbers, which are very difficult to guess via bruteforce (see above).
This means that RSA is a more secure algorithm due to its significantly larger time complexity.

Solution:

• Automation: You can write a program to repeat an action indefinitely .
• Action at a distance: You don’t have to be physically present to begin a security attack.
• Technique propagation: It’s easy to distribute security vulnerability code to others.

Solution:

Passwords are used to verify a person, often through a login with the username as the identity they’re claiming and the password as the verification.

Certificates are used to verify a website by establishing a secure connection with it before encrypted or sensitive information is exchanged.