Codebusters Test Curriculum Framework 3

Question 1

In a columnar transposition cipher, what role does the keyword play in the decryption process?

Accepted Answer

It provides the order in which columns are read to reconstruct the plaintext

Answer

It determines the Caesar shift for each column

Answer

It identifies which letters to skip during decryption

Answer

It sets the number of rails used in the transposition

Question 2

Which cipher is based on encoding letters as pairs of numbers using a Polybius square?

Accepted Answer

Polybius checkerboard cipher

Answer

Porta cipher

Answer

Beaufort cipher

Answer

ADFGVX cipher

Question 3

In the context of Codebusters, what does 'index of coincidence' measure?

Accepted Answer

The probability that two randomly chosen letters in a text are identical

Answer

The number of repeated letters in the ciphertext

Answer

The average shift value of a Caesar cipher

Answer

The key length of a Vigenère cipher in absolute terms

Question 4

The Kasiski test is used in Codebusters to:

Accepted Answer

Estimate the keyword length of a Vigenère cipher by finding repeated sequences

Answer

Verify that a Caesar shift has been applied correctly

Answer

Count digraph frequencies in a substitution cipher

Answer

Determine whether a transposition or substitution cipher was used

Question 5

A Codebusters team encounters a cipher where letters are replaced by symbols from a pigpen-style grid. This is best described as:

Accepted Answer

A symbolic substitution cipher

Answer

A transposition cipher

Answer

A steganographic cipher

Answer

A running key cipher

Question 6

In a Baconian cipher, each plaintext letter is represented by:

Accepted Answer

A 5-character sequence of A's and B's (or binary)

Answer

A pair of Morse code symbols

Answer

Its position in a Polybius square

Answer

A two-digit number from 01 to 26

Question 7

In Codebusters, which property makes a one-time pad (OTP) theoretically unbreakable?

Accepted Answer

The key is truly random, at least as long as the message, and used only once

Answer

It uses an extremely long repeating keyword

Answer

It applies multiple layers of transposition before substitution

Answer

It encrypts digraphs instead of individual letters