Codebusters
Welcome to Codebusters! In this event, teams will cryptanalyze and decode encrypted messages using cryptanalysis techniques for historical and modern advanced ciphers.
The information below should not be interpreted as an extension of the rules. You can find free online copies of the current rules for download on the 2026 Rules page of the Science Olympiad website. The official rules in the current Rules Manual take precedence.
RESOURCES & LINKS 2026 coming soon!
- New '26 Webinar - Codebusters - Advice & Preparation Ideas
- Codebusters Overview - (Updated for 2025) Use this link to access an overview of the Codebusters event containing information about various ciphers as well as instructional resources
- Cipher Summary - Use this link to find a breakdown of the Codebusters ciphers by Division & Tournament Type
- Codebusters Example Resource Sheet - This document provides teams and coaches with an example of what a Codebusters Resource Sheet could look like at a tournament. It is important to understand that the actual sheet may defer from what is posted here as it should be customized for each tournament by the Event Supervisor.
- Generating Cryptarithms for Science Olympiad Codebusters Video
- American Cryptogram Association - has many examples of Aristocrats and Patristocrats, as well as some Xenocrypts
- Recommended Book Resources
- Lesson Plan on Cryptography
Science Olympiad Store Materials
- Updated -Codebusters Starter Pack
- Codebusters Digital Download DVD
- 2026 National Test Packet
- 2025 National Test Packet
- 2024 National Test Packet
- 2023 National Test Packet
- 2022 National Test Packet
PRACTICE PROBLEMS & TESTS
- Practice Test - 2026 BullSO Invitational
- Practice Test - 2026 Wichita Heights High School Invitational
- Practice Test - 2026 GullSO Invitational
- Practice Test - 2026 Northview Invitational
- Practice Test - 2026 Hawk & Hornet Invitational
- Practice Test - 2025 Bulls SO Invitational
- Practice Test - 2025 UW River Falls Border Battle
- Practice Test - 2025 Purdue Invitational
- Practice Test - 2025 Northview Invitational
- Practice Test - 2025 UT Austin Invitational
- Practice Test - 2025 Mira Loma Science Olympiad Invitational
- Practice Test - 2025 Mason High School Invitational
- Codebusters Test Generator and Help Guide from NCSO
- Practice Test - 2024 Brown University Invitational
- Practice Test - 2024 Case Western Reserve University Invitational
- Practice Test - 2023 Northview Invitational
- Practice Test - 2023 UGA Invitational
- Codebusters Exam Archive
- Additional practice problems
- Codebusters Activities
- Cryptoclub practice problems
- Practice Test - 2024 GullSO Invitational
- Practice Test - 2023 Columbia University Invitational
- Practice Test - 2023 University of Michigan Invitational
- Practice Test - 2023 MIT Invitational
- Practice Test - 2023 Northmont Invitational
- Practice Test - 2023 Ohio State University Invitational
- Practice Test - 2023 Carolina Science Olympiad Invitational
- Practice Test - 2022 UT Austin Invitational
- Practice Test - 2022 Rickards Invitational
- Practice Test - 2022 Highlands Invitational
- Practice Test - 2022 BullSO Invitational
- Practice Test - 2022 National Invitational
- Practice Test - 2022 SOLVI Invitational
- Practice Test - 2022 MIT Invitational
- Practice Test - 2022 Northwestern Invitational
- Practice Test - 2022 UChicago Invitational
- Practice Test - 2021 UT Austin Invitational
- Practice Test - 2021 BirdSO Invitational
EVENT SUPERVISOR RESOURCES
In addition to the resources on the Event Supervisors page, Codebusters Event Supervisors should be sure to use the following resources:
- Event Logistics Resource
- Practice Exam Writing Tool and Training Video
- Codebusters Exam Writer