Codebusters Test Curriculum Framework 2 — Questions and Answers
Question 1: In the Codebusters Science Olympiad event, which cipher uses a 5x5 grid of letters where I and J share one cell?
- Playfair cipher (Correct answer)
- Vigenère cipher
- Rail fence cipher
- Caesar cipher
Correct answer: Playfair cipher
The Playfair cipher uses a 5x5 key square where I and J are combined into a single cell to fit the 26-letter alphabet.
Question 2: When analyzing a monoalphabetic substitution cipher in Codebusters, which letter in English plaintext has the highest expected frequency?
- A
- E (Correct answer)
- T
- S
Correct answer: E
The letter E is the most frequently occurring letter in standard English text, appearing approximately 13% of the time.
Question 3: Which Codebusters cipher type encrypts by writing the message along multiple diagonal rails and reading off row by row?
- Columnar transposition
- Rail fence cipher (Correct answer)
- Route cipher
- Grille cipher
Correct answer: Rail fence cipher
The rail fence cipher writes plaintext diagonally across a specified number of 'rails' and reads the ciphertext row by row.
Question 4: In the Codebusters curriculum, an 'aristocrat' differs from a 'patristocrat' primarily because:
- It uses a keyword to generate the cipher alphabet
- It retains the original word spacing from the plaintext (Correct answer)
- It uses numbers instead of letters for ciphertext
- It requires a Vigenère tableau to solve
Correct answer: It retains the original word spacing from the plaintext
An aristocrat preserves the original word spacing, while a patristocrat groups all letters into fixed-length blocks, removing word boundaries.
Question 5: The Vigenère cipher is considered polyalphabetic because it:
- Uses multiple cipher wheels simultaneously
- Encrypts each letter using a different Caesar shift based on a repeating keyword (Correct answer)
- Changes the cipher alphabet after every 26 letters
- Requires two separate keys to encrypt a message
Correct answer: Encrypts each letter using a different Caesar shift based on a repeating keyword
The Vigenère cipher applies a different Caesar shift to each letter based on the corresponding letter of a repeating keyword, creating multiple cipher alphabets.
Question 6: In Codebusters scoring, what is the primary advantage of completing a timed question (with a bonus) over a non-timed question?
- Timed completions earn triple points
- Timed completions earn additional bonus points on top of the base score (Correct answer)
- Only timed questions count toward the final team score
- Timed questions cannot be penalized for wrong answers
Correct answer: Timed completions earn additional bonus points on top of the base score
In Codebusters, solving the timed question earns a base score plus a time bonus, rewarding teams that solve it quickly and accurately.
Question 7: Which mathematical concept is fundamental to the RSA encryption algorithm sometimes referenced in advanced Codebusters problems?
- Matrix multiplication
- Prime factorization of large numbers (Correct answer)
- Polynomial long division
- Fibonacci sequences
Correct answer: Prime factorization of large numbers
RSA security relies on the computational difficulty of factoring the product of two large prime numbers.
Codebusters Test Curriculum Framework 2
In the Codebusters Science Olympiad event, which cipher uses a 5x5 grid of letters where I and J share one cell?