Codebusters Test Codebusters Pattern Recognition 2

Question 1

In an Aristocrat cipher, the ciphertext letter 'Q' appears far more frequently than any other letter. What is the most likely plaintext equivalent?

Accepted Answer

E

Answer

Z

Answer

X

Answer

Q

Question 2

A ciphertext word reads 'VHOO'. What common English word does the ABCC double-letter pattern suggest?

Accepted Answer

TELL

Answer

WORD

Answer

SHIP

Answer

FAST

Question 3

In a Caesar cipher with a shift of 13 (ROT13), what does the ciphertext 'URYYB' decode to?

Accepted Answer

HELLO

Answer

WORLD

Answer

CODES

Answer

GAMES

Question 4

Which digraph (two-letter combination) appears most frequently in standard English text?

Accepted Answer

TH

Answer

QU

Answer

ZX

Answer

BV

Question 5

A ciphertext contains the single-letter word 'X'. What are the two most likely plaintext letters it represents?

Accepted Answer

A or I

Answer

E or T

Answer

S or N

Answer

O or R

Question 6

In a Patristocrat cipher, spaces between words are removed. Which technique is most useful for finding word boundaries?

Accepted Answer

Identifying frequently repeated 2-3 letter sequences

Answer

Trying all 25 Caesar shifts

Answer

Converting letters to numbers

Answer

Matching Morse code dot-dash patterns

Question 7

A ciphertext ends with the 4-letter pattern 'JKKJ'. Which common English word has the same ABBA structure?

Accepted Answer

NOON

Answer

ABLE

Answer

TION

Answer

NESS