5.08 Limits of Algorithms

5.8 Limits of Algorithms Curriculum Page

Portfolio Reflection Questions:

1. (POGIL) A password scheme consists of a minimum password length and the different types of symbols (i.e., letters, numbers, specials) that can be used in the password. Using the Password Strength Calculator, determine the optimal scheme for withstanding a brute force attack of at least 10 years by an ordinary PC performing 100 million tests per second.
   • The optimal scheme for withstanding a brute force attack of at least 10 years by an ordinary PC performing 100 million tests per second is to have a password that is long with many different types of symbols. A password that would take more than 10 years to crack has a length of at least 9, with a combination of uppercase letters, lowercase letters, numbers, and special keyboard characters.
2. (POGIL) According to this 2012 article, a password-cracking computer can try 350 billion passwords per second. How would you have to modify your scheme to withstand a 10-year attack by this specially designed computer?
   • You would need to increase the length of the password to 11 and include uppercase letters, lowercase letters, numbers, and special keyboard characters.
3. (POGIL) That article was written in 2012. Password cracking technology has probably gotten a lot better. Suppose the number of passwords that can be checked per second doubles every year, use the Password Strength Calculator to determine an optimal password scheme for the year 2020?
   • An optimal password scheme for the year 2020 is a password that has a length of at least 12 and includes uppercase letters, lowercase letters, numbers, and special keyboard symbols. By the year 2020, it would mean that the computer would try 6 billion 4 hundred million guesses per second.
4. (POGIL) For the routes starting and ending at Trinity College, identify the nearest neighbor route and the optimal route. What does this show you about the nearest neighbor heuristic?
   • The nearest neighbor heuristic route isn’t always the optimal choice. There can be other ways to find a route that would be faster than just going point by point, finding the nearest spot. As seen through our nearest neighbor route, it is 8.2 miles vs our optimal route which is 6.2 miles.