Codebreaking 101 · Part 2 of 8. A friendly, no-maths series for brand-new cryptogram solvers. A new part arrives every Wednesday.
Last week, in What Is a Cryptogram?, we met the swap code and its three house rules, and cracked a first tiny case together. If you missed it, go and have a look. I’ll keep the kettle on.
This week is the trick I reach for first, every single time: start with the tiny words. If you’ve been wondering how to solve cryptograms as a beginner without staring at the page until the letters start staring back, this is your way in.
Think of a cryptogram as a room full of suspects. The long words are smooth talkers with a story for everything. The tiny words are the nervous witnesses in the corner: there are only so many things they could be, and with gentle questioning, they talk.
Why tiny words crack the case
A one-letter word can only be one of a very short list of real words. A two-letter word has a few dozen options. A three-letter word has more, but a handful of them turn up so often that they’re nearly always worth trying first.
And remember house rule one from Part 1: a swap is a swap for the whole message. So every tiny word you crack hands you letters you can use everywhere else. Three little words can easily give you six or seven letters, and that’s often enough to make the long words blush and confess.
The one-letter suspects: A and I
In everyday English, a word made of a single letter is almost always A or I. (Very occasionally an old poem says “O”, as in “O night, O stars”, but poets are a law unto themselves.)
- One single-letter word? It’s A or I. Pencil in both and let the rest of the message decide.
- Two different single-letter words? Lovely. One is A and the other is I, because each code letter stands for just one real letter.
- Is the lonely code letter itself an I? Then it must be A. House rule two: no letter stands for itself.
The two-letter line-up
Two-letter words are the busiest little words in the language. Here are the regulars worth knowing by heart:
OF, TO, IN, IT, IS, BE, AS, AT, SO, WE, HE, BY, OR, ON, DO, IF, ME, MY, UP, AN, GO, NO, US, AM
No need to memorise it today. Just notice the families:
- Same first letter: IT, IS, IN and IF all start with I. OF, ON and OR all start with O. If two code words share a first letter, try those families.
- Same last letter: IT and AT end in T. TO, SO, DO, GO and NO end in O.
- A word that turns up again and again in a short message is a good candidate for IT, IS, OF or TO.
Once you know which one-letter word is I, the two-letter words starting with that code letter fall like dominoes: IT, IS, IN.
The three-letter heavyweights: THE and AND
As we saw in Part 1, THE is the most common word in English, so a three-letter word that appears more than once is a strong suspect for THE. AND is never far behind it.
Two quick tests help you tell them apart:
- If you already know a one-letter word is A, then a three-letter word that starts with that same code letter is very often AND.
- If you know which code letter is T (from IT or TO, say), a three-letter word starting with it is often THE.
Other three-letter regulars worth trying: FOR, ARE, BUT, NOT, YOU, ALL, WAS, HIS, HER, HAS and ONE.
Your pocket cheat sheet
- Circle every one- and two-letter word.
- Decide A or I for the lonely letters.
- Look for two-letter twins that share a letter (IT and IS, TO and IT).
- Find the repeated three-letter word and try THE. Try AND next to an A.
- Write every new letter in across the whole message, then step back and read.
Case one: the warm-up
Here’s a short line I wrote for this lesson, packed with tiny words. See how far you get using only the small ones, then fill in the rest:
TX TQ D XBDF, DZI XWY MOXUYB HZAGQ TX.
Clue 1: the lonely letter. D stands alone, so it’s A or I.
Clue 2: the two-letter twins. TX and TQ start with the same code letter, and TX turns up twice, at the very start and the very end. Which family of two-letter words shares a first letter and loves to bookend a sentence?
Clue 3: the three-letter pair. Once you know D, look at DZI. And once you know the code letter for T, look at XWY.
Fill in what you’re sure of, pencil in what you suspect, and see who walks out of the shadows.
Open the sealed envelope: the solution
The message: IT IS A TRAP, AND THE BUTLER KNOWS IT.
- TX and TQ share a first letter: the I family. So T = I, and the twins are IT and IS. That gives X = T and Q = S.
- T is now I, so the lonely D can’t be I as well. D = A.
- DZI is A__: AND. So Z = N and I = D.
- XWY starts with T: THE. So W = H and Y = E.
- Now the long words: XBDF reads T_A_, and “it is a T_A_” can only be a TRAP. HZAGQ is _N__S: KNOWS. And MOXUYB, now __T_ER, is our old friend the BUTLER. He always knows.
The full key we found: D=A, M=B, I=D, Y=E, W=H, T=I, H=K, U=L, Z=N, A=O, F=P, B=R, Q=S, X=T, O=U, G=W.
Five tiny words did nearly all the work. The long words just had to own up.
Case two: the stretch
This one is longer, and it’s positively stuffed with tiny words. One hint: there are two different one-letter words in it. You know what that means.
H FHO VFZ JZI HD S KAAJ AP NAZQG KI VFZ OAAW, SDO DA ADZ HG VA VATYF HV.
Open the sealed envelope: the solution
The message: I HID THE KEY IN A BOOK OF POEMS BY THE DOOR, AND NO ONE IS TO TOUCH IT.
- H and S are both one-letter words, so one is A and the other is I.
- VFZ appears twice: try THE. So V = T, F = H and Z = E.
- SDO starts with S. If S were I, we’d need a three-letter word starting with I. If S is A, it’s AND, the second heavyweight. So S = A, D = N and O = D, which makes H = I.
- The two-letter words fall like dominoes: HD = IN, HG = IS, HV = IT, VA = TO (so A = O), DA = NO and AP = OF.
- FHO = HID, ADZ = ONE and OAAW = DOO_: DOOR. “I hid the _E_” is surely a KEY, so KI is _Y: BY. Then KAAJ is BOOK, NAZQG (_OE_S) is POEMS, and VATYF (TO__H) is TOUCH.
The full key we found: S=A, K=B, Y=C, O=D, Z=E, P=F, F=H, H=I, J=K, Q=M, D=N, A=O, N=P, W=R, G=S, V=T, T=U, I=Y.
Count them: fifteen of the nineteen words were three letters or fewer. That’s why this trick is the first thing I teach.
Three tiny traps to avoid
- Don’t ink it in. A and I can swap places on you. Use a pencil until the message reads like English.
- Don’t force THE. If a repeated three-letter word has the same first and last letter (like DID or DAD), it can’t be THE. Move on to the next suspect.
- Don’t forget rule two. No letter stands for itself, so a code T is never a real T. It sounds obvious, but it saves a lot of wrong turns late at night.
If you’re wondering whether all this puzzling is good for your brain, I’ve looked at what the research actually says in Are Puzzles Good for Your Brain? (spoiler: modest conclusions, lovely hobby).
Coming up in Codebreaking 101
- What is a cryptogram?
- The tiny-word trick: A, I, THE and AND (you are here)
- Apostrophes and letter patterns
- Letter frequency, without the maths
- Double letters and word shapes
- Stuck? What real codebreakers do next
- Your first full-size cryptogram, start to finish
- From beginner to Armchair Detective
Your next move
Put the tiny-word trick to work on today’s free Daily Cryptogram. Circle the short words first and watch how fast the rest gives way. If you get stuck, you can reveal a letter (up to three) or switch on “Show mistakes” while you learn.
When you’re ready for a whole evening of codes, True Crime Cryptograms from my Armchair Detective Casebook series is a lovely next step. Pour the tea, sharpen the pencil, start with the tiny words.
And since it’s November and the gift lists are starting to appear: if there’s a puzzle lover in your life, Christmas Cryptograms makes a cosy little stocking stuffer. (Buying one for yourself “to check it’s suitable” is entirely acceptable detective procedure.)
Want new cases before anyone else? Join The Case File Letter, my little dispatch of fresh puzzles and book news.
Next Wednesday: apostrophes and letter patterns, the clues hiding in plain sight. Bring your pencil, and keep an eye on that butler.
— Ivy
Ready for a real case?
Try today’s free Daily Cryptogram, or pick up a casebook.