What is Codebusters?
Codebusters is a team cryptography event where you break encoded messages using frequency analysis, cribs, math, and cipher-specific techniques. It shows up in both middle and high school, but the cipher list and difficulty differ by division, so train from the current rules for your level.
Cipher differences by division
Always confirm against this year's official rules. These are the families teams train most.
Division B ciphers
- Aristocrats & Patristocrats
- Caesar / Affine / Atbash-style ciphers
- Vigenère and related keyword ciphers
- Baconian, Morse, and other specials in the rules
- Hill cipher when included for the season
Division C ciphers
- Harder aristocrats / patristocrats under tighter time
- Xenocrypts (Spanish frequencies + cognates)
- Affine, Vigenère, Hill, and number-theory topics as listed
- Pollux, Baconian, Porta, and other specials from the rules
- Fractionated Morse / running key variants when included
Daily: 1-2 timed aristocrats. Weekly: one mixed packet. Before invitationals: a full timed run with locked partner roles.
Workshop videos
These are the Codebusters Day 1 and Day 2 sessions from my SciOly Tutor summer workshop (Div B). Watch them here, then use the links below for rules, practice tools, and more.
Day 1 workshop
Intro to Codebusters and the core ciphers we covered in Div B session 1.
Open on YouTubeDay 2 workshop
Follow-up session with more ciphers, practice, and timing tips from Day 2.
Open on YouTubeRules, wiki & tools
Official rules
Current Codebusters event page from SOINC.
SOINC CodebustersRules manuals
Download the Div B / Div C manuals for your season.
SOINCScioly wiki
Event overview, strategies, and community notes.
Wiki: CodebustersToebes Codebusters
Practice tests, timers, and cipher generators.
toebes.comTest exchange
Past tests for timed partner practice.
Scioly testsMore SciOly Tutor videos
Other cipher walkthroughs and strategy videos on the channel.
YouTube channel