Codebusters Workshop

Caleb “Klebb” Chiang

Sierra Vista Invitational 2024

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Agenda

Introduction

Team Strategy & Structure

Micro- Strategies

General Advice & How to Learn

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Introduction

Hi! I’m Klebb (they/he).

• Junior @ University of Illinois Urbana-Champaign
• Mathematics & Secondary Education
• Prev. Hopkins JHS, Mission San Jose HS
• Competed 2014-2021, ESing 2021-Just Now!

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Overview

• We will NOT focus on how each cipher works, rather strategies for competing effectively
• Target is intermediate teams, but everyone can take something away from this
• Note that these are strategies that worked for me (and the people I’ve worked with), not necessarily everyone!
• I will not answer anything about “good” vs. “bad” scores

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Team Strategy & Structure

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A Quick Thought Exercise

For the sake of argument, assume that there are 50*3 = 150 total “working minutes” among the three team members

Having 2 people work on a question for 3 minutes means you spend 6 “working minutes”, while doing it alone may only take 4 minutes…

When, if ever, is it worth it to spend more working minutes than needed on a question? When does “actual time” matter?

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Timed Question

Put at least 2 people on timed question! 3-person setups also can work depending on your team

Find a setup to write on different parts of the question

• One right-handed & one left-handed person works great

Transition into the test as smoothly as possible

• Have one person look through the test & split up papers as the other two finish

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The Test

Have a plan going in of who is doing what ciphers

• Find roles that work for your team based on your individual abilities
• Be flexible! Adapt your plan to the needs of the test

Designate a team leader/shotcaller to make final decisions

Keep morale up, especially if and when unexpected situations arise; make “all good” your motto mid-test

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Endgame

Shift gears in the final ~10-15 minutes away from “doing the test” to finishing individual questions

Team Leader should make a rough roadmap of what to finish in order of priority at this point

• Very common to double up on questions starting now

Be prepared to adjust strategy as needed

Play extra aggressive here!

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Communication

Codebusters communication comes in 3 main forms: facilitation, help, and morale

Facilitation: Test-wide strategy, what questions are on what page, when you finish or start a question, etc.

Help: Individual question needs: asking for word patterns, Morse Code, cipher mechanics, etc.

Morale: Keeping team spirits high, especially if someone can’t figure out a question

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Communication (2)

Good communication is frequent, clear, and positive.

“Keeping the vibes up” is important; you’re a team, so work together and build off of one another!

Make sure everyone is on the same page on what is done, and what needs to be done by whom

Call out whenever you’re stuck on a question for help, or to move on if you’re stuck.

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Communication (3)

Example! Here are some quotes from a session we recorded after the MIT Invitational a couple weeks ago:

“Porta, pat, I’ll take this page, … Word bacon, I can take a stab at I guess, and this is some more Aristos, which I think you can take a look at” (hands page)

“K3 done, can I have ref? I’m going to do Porta now”

“It [cryptarithm] will be probably sort of rough, so don’t beat yourself up over it; if you’re staring at it and not getting anywhere then just move on it’s okay”

“Okay, done with this Frac. Morse” “Okay, Xeno here” “Yeah I think I’ll do that now”

“Oh it’s just the… does anyone know the really long fish name off the top of their head?”

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Micro-Strategy

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Why Aristocrats First

Aristocrats are the most fundamental cipher in Codebusters:

• They often make up around 30% of a test
• The skills you learn from doing Aristocrats translate to every other cipher in some way

No matter your role on your team, I recommend being at least somewhat proficient at Aristocrats

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Stop Relying on (only) Frequency

It’s a common mistake to over-rely on frequency

Try to think of Aristocrats on at least 4 levels: letters, letter combinations, words, phrases/sentences/clauses

Word patterns should become your best friend; you probably use some already like ABCADB = PEOPLE

Think about sub-parts of words like -TION, -ING, or -ED

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Use Grammar & Syntax

Thinking bigger picture on the phrase to sentence level can be very powerful, as you can potentially get a lot of information in a very short amount of time

Small things like subject-verb agreement can get you free letters at the very least (usually an S or ARE or something)

Knowing which parts of speech are possible depending on where you are in the sentence limits the guesswork you need

Punctuation can provide conjunctions, contractions, etc.

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Quick Grammar Quiz/Lesson!

What is…

• A noun?
• A verb?
• A subject vs. an object?
• A preposition?
• A clause?
• Indirect speech?
• An Oxford Comma?

You don’t need to know these terms, but try to think about how sentences are constructed, and how you can use that to your advantage

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Example of How I Used Grammar Once

2021 GGSO C #13: You've received a secret message encoding the location of a suspicious package. Using a Patristocrat cipher, determine the location in question.

MFORC SBRGB TNCGZ PXRXS SPSBR JTSBC PPVPF

SBRCN IBSBT FOXNO R

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Abusing K1 & K2

K1 & K2 are very exploitable; use them to your advantage!

As soon as you have an idea where the key is in the alphabet (or just an idea where it is not), start filling in letters alphabetically!

Take advantage of the infamous VWXYZ trick, and its cousins the PQ and JK tricks. These low-frequency letters stick out in tables and don’t usually show up in keys!

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Worked Examples!

2023 MIT C #22

2023 SV B #2

2023 SV B #20

2023 SV B #23

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Xenocrypts & Patristocrats

Spanish is very regular in comparison to English, so even if your vocabulary is limited a strong understanding of Spanish’s rules and grammar will get you very far

For Patristocrats especially, scan the entire ciphertext first to look for anything that may be useful. Noticing a few letters appear together repeatedly can be a break-in (MIT 2020).

Practice, practice, practice!

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General Advice & How to Learn

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Practicing vs. Studying

Codebusters is a practice event, not a study event!

Question: What is Codebusters actually about?

My Answer: Not really cryptography, that’s for sure. Instead, maybe:

• Linguistics
• Puzzle-solving
• Pattern-recognition
• Strategy Development?

Get away from thinking about this event in terms of its “content”; instead think more about the skills you’re building.

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How to Practice

Codebusters is a lot like learning any other skill, be it a musical instrument, sport, language, or card magic.

• Practice a little bit regularly (e.g., 30 minutes each day)
• Long practice sessions also have their use for endurance and to practice team strategy
• Practice both with your team & individually; stay sharp!
• Taking some time to develop strategy is worth it too!

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How to Practice (2)

• Scrimmage with teammates and/or other teams
• Friendly competition makes improvement fun and challenges you to give your best effort
• Practice with different test/cipher compositions
• Use sites like cryptograms.org wisely
• Great for learning a lot very quickly early on
• Results diminish over time, but still useful for warm-up/staying sharp
• Aristocrats are important for everyone to be proficient at

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How to Practice (3)

Let me share how I learn new ciphers each year:

1. Read up on how the cipher works & play around with an encoder/decoder
2. Work through one example slowly in full detail, possibly with known plaintext
3. Do a few more practice examples until I’m comfortable

It’s really that simple! Don’t spend too long reading; spend more time doing.

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Playing Aggressive

Two schools of thought on how to approach Codebusters:

• Deduction: Solve questions using step-by-step processes, making sure or almost-sure logical decisions along the way
• Intuition: Solve questions by making assumptions based on patterns and checking if they work after/as you go

In other words, low- vs. high-risk playstyles

Which do you gravitate towards? Why?

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Playing Aggressive (2)

I tend to lean more towards intuition, the main reason being speed

• Try to suppress the fear of being wrong:
• Make fast, bold guesses (e.g., words & phrases vs. letters)
• Constantly sanity check your work as you go
• Trust your intuition that is built up from practice

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Other Miscellaneous Tips

Warming up on competition day is important! Do some cryptograms, play some 24, solve a crossword, etc.

Don’t worry too much about memorizing things like Morse Code, Baconian alphabet, etc. They’ll come with time as you use them!

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Questions?

(I may do some examples too)

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