Codebusters Test Graduation Requirements 4

Question 1

In Codebusters, what does it mean when a cipher is labeled 'K1' in the key phrase system?

Accepted Answer

The keyword is placed starting at letter A in the plaintext alphabet

Answer

The keyword is placed starting at letter A in the ciphertext alphabet

Answer

The cipher uses a single-letter key

Answer

The cipher is at difficulty level 1

Question 2

What is the graduation requirement for understanding 'Morbit' cipher used in advanced Codebusters events?

Accepted Answer

A cipher using Morse code fragments encoded with a key

Answer

A cipher based on monoalphabetic bit-shifting

Answer

A cipher derived from the Polybius square with nulls

Answer

A columnar transposition using a 4×4 grid

Question 3

Which technique is a graduation requirement for cracking the columnar transposition cipher?

Accepted Answer

Anagramming columns to find readable digrams

Answer

Frequency analysis of individual letters

Answer

Applying the Kasiski test for key length

Answer

Using the index of coincidence on each row

Question 4

For Codebusters graduation at the invitational level, which of these cipher types is students are NOT required to encode (only decode)?

Accepted Answer

Porta cipher

Answer

Caesar cipher

Answer

Atbash cipher

Answer

Morse code

Question 5

What graduation skill involves using the 'unicity distance' concept to determine when enough ciphertext exists to uniquely solve a cipher?

Accepted Answer

Information theory application to cryptanalysis

Answer

Index of coincidence measurement

Answer

Key length determination in Vigenere

Answer

Frequency analysis threshold assessment

Question 6

In Science Olympiad Codebusters, what happens if a team submits an answer sheet before the event time expires?

Accepted Answer

Time stops for that team and final score is recorded

Answer

They receive a 10% bonus on their score

Answer

They may continue working on remaining ciphers

Answer

They receive extra time to double-check answers

Question 7

Which graduation requirement concept explains why 'one-time pad' ciphers are theoretically unbreakable?

Accepted Answer

The key is truly random and never reused

Answer

The key is longer than the message

Answer

The cipher uses modular arithmetic

Answer

The key is stored securely off-site