Sunday, June 14, 2015

What's A Crytogram and How Do I Solve Them?

When people started using codes for messages, a simple code was good enough. Check out substitution codes and Augusta's code in the blog. As people got familiar with codes, they realized that they could be "broken", even if you didn't have a decoder ring. People got so good at breaking substitution codes that they started using them as puzzles called cryptograms. Cryptograms are still printed in some newspapers and you can buy books full of them at the supermarket, but the internet allows you to enjoy solving cryptograms anytime you want to.

A cryptogram is a block of text which has been made unreadable through the use of what is called a "substitution cypher"(Check it out in the blog list). This means that each letter used in the original text has been substituted with another (G becomes A, F becomes P, etc.). Letter/word positions, spaces and punctuation remain unchanged.

Instead of making up some cryptograms, I have put a link to a site that specializes in cryptograms below. I'm also going to list some of their hints on how to solve them.

Solving Cryptograms

 #1. Start with the one-letter words.
Many, if not most puzzles, will have one or more words which are composed of only a single letter. In the English language, the only two commonly used one-letter words are I and a, so it's usually a safe bet that any single-letter word in your puzzle can be decoded to one of those two.

#2. Frequency analysis and the importance of ETAOIN.
Frequency analysis is a fancy term for a simple idea - certain letters appear far more often in the English language than others. That's where ETAOIN comes in handy. No, that's not the name of an exotic tribe or an extinct tongue. ETAOIN is simply a mnemonic device combining the six letters which appear most frequently in the English language. The letter 'E' appears much more frequently than any other letter in the alphabet, with 'T' the most common after that, 'A' the third most common, and so on.
How does this help? Well, you'll notice in our ( cryptograms, we provide a number below each letter. That number tells you how often that particular letter appears in the puzzle (i.e. that letter's "frequency analysis"). If, for example, a letter appears twelve times in a puzzle, much more often than any other letter, then it is a very good bet (though by no means certain) that that letter can be decoded to one of the ETAOIN group. More often than not, it will decode to 'E' or 'T'.

#3. Contractions and possessives are your friend.

You may have hated learning about contractions, but here in crypto-land, contractions are extremely useful! Contractions are simply words that combine two words into a shorter, single word by replacing certain internal letters with an apostrophe. Some examples are don't, they've, he'll, he's, I'm, she'd, etc. Possessives also use apostrophes in a similar way, to show ownership - i.e. woman's, child's, dog's, etc.
The reason contractions and possessives are so useful in decoding cryptograms is that only a small number of letters can be used in them immediately after the apostrophe. Possessives will only ever use 'S' - contractions have more options, however:
Common Endings for Contractions (With Examples)

'Twon't don't isn't aren't weren't shouldn't didn't can't
'She's she's it's
'DI'd he'd she'd they'd
'REthey're you're
'VEthey've you've
'LLI'll he'll she'll they'll it'll

#4. Move on to the two- and three-letter words.
By now you maybe have placed an 'A' or an 'I' on the board, if there were any one-letter words available, and maybe you've even placed an 'E' or a 'T' via frequency analysis. At this point you may start to see some two- and three-letter words which now have a single letter decoded in them. There are only a handful of common two-letter words, and not very many more three-letter words, so you can start analyzing each to see where they may and may not fit.
Most Common Two- and Three-Letter Words

Two Letters:of to in it is be as at so we he by or on do if me my up an go no us am
Three Letters:the and for are but not you all any can had her was one our out day get has him his how man

Be especially sure to search for appearances of 'THE' and 'AND' - two of the most commonly used words in the english language. Even if no letters have yet been decoded you can often use frequency analysis (remember ETAOIN?) to find one or both of these words. Look for three letter words with a frequency analysis pattern of HIGH-MEDIUM-HIGH (for 'THE') and HIGH-HIGH-MEDIUM (for 'AND').

#5. Look for digraph patterns.

Certain less-common letters in the english language tend to "pair up" with other letters in two-letter sequences commonly referred to as "digraphs." 'H' is one example - particularly when it is the last letter of a word. A partially-decoded word like ----H, for example, will probably end in -CH, -PH, -SH or -TH, just because there are very few other letters that can pair up with H near the end of a word.
Useful Letters with Commonly Appearing Digraphs


It is also extremely useful to look for double-letter digraphs, i.e. letters which appear in duplicate (one directly after the other) in the same word. These can often be a dead giveaway, and especially so in 3- and 4-letter words. Only two vowels, 'E' and 'O', are commonly used as double-letter vowel digraphs.
Common Words with Double-Letter Digraphs

3 Lettersall add bee boo ell ebb egg fee goo too tee see
4 Lettersball been beer beet beep bell boom boot book bull butt call cell coon dell doll door doom fall fell feel feet foot food fool fuss full gull gall hall hell heed heel hill hull hoop hood hoof hoot jeep keen keel keep less lees mall need peel pall pool poof poll poor peek pass root reel reef reed roll room rood sass sell seen seem seed seek seer seep soon soot sill tall tell teen teem teed tool wall well watt weed week weep

#6. Consider common prefixes and suffixes

Longer words with more than 5 or 6 letters will often contain prefixes and/or suffixes, both of which can be a big help in decoding a puzzle. Try to keep some of the more common prefixes and suffixes in mind for these longer words, and see if any of them might fit the bill.
Common Prefixes and Suffixes

PrefixesDE- DIS- EN- EM- IN- IM- MIS- OVER- PRE- RE- UN-

Some of those suffixes also have frequently appearing, longer variants which can sometimes decode additional letters:
Common Suffix Variants


#7. Remember the more common words.

We've already covered common words with one, two and three letters, but there are a handful of other, longer words which also appear frequently in the english language.
Common English Language Words

4 lettersthat with have this will your from they know want been good much some time very when come here just like long make many more only over such take than them well were
5 lettersabout where which their there today every would after other being first great these since under where while after
6+ lettersthrough people between before

I like cryptograms, but they are hard to make up and take a lot of effort to solve. One of my favorite places for cryptograms is here: - online and printable cryptograms.
You can get your cryptograms with the letters already counted and a "used letter" list that updates as you fill in the chart. The hints above are from this site.

No comments:

Post a Comment

Comments are always welcome.