Codebusters

Codebusters is an event in which teams of up to 3 work together to decode encrypted messages using cryptanalysis techniques for both modern and historical ciphers. 

The event begins with an initial timed cipher-- if solved within 10 minutes of the event start, extra points are awarded. If completed correctly after 10 minutes, base points are awarded. Competitors can split up the problems, and work on them individually or collaboratively. Points are awarded based on correct answers, and if partially completed, are based on the number of correct letters.

Ciphers

Ciphers can include: Caesar, Atbash, mono-alphabetic substitution (Aristocrats, Patristocrats), Affine, Vigenère, Baconian, Xenocrypt, Pollux and Morbit, and Rail Fence cyphers.  

Resources

You may bring writing utensils and up to 3 basic calculators (non-programmable, not graphing, non-scientific). You may not bring references. 

During the test, you will be given a resource sheet with the Morse Code Table, English/Spanish letter frequencies, Vigenère table, Baconian mapping and modulus inverse tables as needed for the questions on the exam. You will be given scratch paper.

Rules PDF – LINK

Resource material is not allowed in this event. However, the team or group is provided with charts such as an English/Spanish letter frequency chart or a baconian chart, etc. 

Materials:

• Pencil

• Calculator

YouTube playlist with some (not all) tutorials/explanations – LINK

PuzzleBaron Aristocrat practice – LINK   (super fun!)

dCode cipher identifier (w/ explanations) – LINK

Codebusters resouces page 

2021 UT Invitational Practice Test, Key

2022 MIT Invitational Practice Test, Key

2022 Northwestern Invitational Practice Test and Key

2022 UChicago Invitational Practice Test and Key