Event Rules
Are you allowed to bring your own notes to the Codebusters study event at competition?
No, it is prohibited.
What is the bonus cipher (usually)
Baconian, Columnar, or Nihilist
What is the Caesar cipher?
This cipher shifts every letter a fixed number down the alphabet. Julius Caesar famously used it.
What is the Aristocrat cipher?
messages with spaces (sometimes encoded with a K1 alphabet)
How would you decode ABC in caesar cipher in a shift of 3?
"ABC" becomes "DEF".
Because you shift it to the right 3 times.
What do you do in Codebusters?
You are supposed to decipher encrypted messages using cryptanalysis.
What is the Caesar cipher?
Shift each letter in the ciphertext backward through the alphabet by the number of positions used in the original encryption.
In a simple substitution cipher, this common letter appears most frequently in English and is often a good starting guess.
E
What is the alphabet from in the Atbash Cipher?
A=Z, swap A and Z, so instead of ABC it is ZYX, and so on.
What would happen if you started before the judges told you to start, and why?
The judges would disqualify you because you are supposed to start when the judges tell you.
Do you get more points if you finish before others, or is it the same?
You get more points
What is the Baconian cipher?
Specialized ciphers based on codes or patterns.
This cipher uses a repeating keyword to shift letters multiple different amounts instead of just one fixed shift.
Vigenère cipher
What is the alphabet from in the Caesar Shift Cipher?
A=S It starts from S, and goes STUVWXYZABCDEFHIJKLMNOPQR
If the most common letter in the ciphertext is X, would it be safe to immediately assume X = E? Why or why not?
No — it’s not always safe to immediately assume X = E. This is because in English, E is the most common letter, so it’s a good starting hypothesis.
When can teams start the test, and when must they stop?
Teams cannot open the test or write before the start signal, and must stop immediately when time is called.
What is the Xenocrypt cipher
Similar to Aristocrat, but in a foreign language (usually Spanish).
This code represents letters using dots and dashes and is often tested in Codebusters.
What is the alphabet in the Affine Cipher?
A=0, so instead of ABC, it is A=0, B=,1 C=2.
You solve half of a cipher but get stuck. A) Keep working on it. B) Switch to another cipher and come back. And why?
B is the correct answer because you can always come back and refresh your brain and do ciphers you know how to do.
How do the scoring each question?
Points may be deducted for errors, but small mistakes (e.g., 1-2 letters) on certain ciphers might not lose points. No letter can decode to itself in Aristocrats, Patristocrats, or Xenocrypts.
What is the Porta cipher
The Porta cipher is a 16th-century polyalphabetic substitution cipher using 13 reciprocal, sliding alphabets controlled by a keyword.
In an Atbash cipher, the alphabet is reversed. If A becomes Z and B becomes Y, this letter would be the encrypted form of M.
N
This term refers to a cipher that keeps the same letter substitutions throughout the entire message.
Monoalphabetic cipher
In a transposition cipher, the frequency of letters in the ciphertext is the same as in the original plaintext. true or false and why?
True because A transposition cipher rearranges letters, so it does not change any letters.