Codebusters Test Graduation Requirements 5

Question 1

Which cipher, required for Codebusters national-level graduation, uses a tableau of 26 shifted alphabets selected by a keyword letter?

Accepted Answer

Vigenere cipher

Answer

Beaufort cipher

Answer

Playfair cipher

Answer

Four-square cipher

Question 2

When a Codebusters competitor analyzes a cipher and finds an IC of approximately 0.038, what type of cipher are they most likely facing?

Accepted Answer

A Vigenere cipher with a long key

Answer

A Caesar cipher with small shift

Answer

An Aristocrat monoalphabetic cipher

Answer

A Rail Fence transposition cipher

Question 3

The Playfair cipher, a graduation requirement at higher Codebusters levels, encrypts plaintext in units of how many letters?

Accepted Answer

Digrams (pairs)

Answer

Single letters

Answer

Trigrams (triplets)

Answer

Quadgrams (quads)

Question 4

For Codebusters graduation requirements, what is a 'null' in the context of cipher messages?

Accepted Answer

A meaningless character inserted to disguise message length or structure

Answer

A letter that always encrypts to itself

Answer

A zero value in a mathematical cipher

Answer

The final letter in every encoded message

Question 5

In Codebusters competition rules, what does the term 'keyword alphabet' mean for a substitution cipher?

Accepted Answer

An alphabet where a keyword is written first, then unused letters follow in order

Answer

The set of letters used only in the keyword

Answer

The alphabet used exclusively for the cipher key

Answer

A scrambled alphabet generated by a random process

Question 6

What graduation competency requires Codebusters competitors to solve a cryptarithm, such as SEND + MORE = MONEY?

Accepted Answer

Assigning digits 0-9 to letters so the arithmetic equation holds true

Answer

Finding a keyword that encodes the equation text

Answer

Applying Caesar shifts to the arithmetic operators

Answer

Using frequency analysis on repeated letter patterns in the equation

Question 7

At which Science Olympiad competition tier do Codebusters graduation requirements first include the Hills cipher (matrix multiplication cipher)?

Accepted Answer

National level

Answer

Invitational level

Answer

Regional level

Answer

State level