Howto

The Crypto-Cross_Up puzzle is a new take on the classic cryptogram.

What is a Cryptogram?

The cryptogram has been around for centuries as a way to keep messages a secret. A substitution alphabet is made by assigning a different letter to each letter of the alphabet. For example:

abcdefghijklmnopqrstuvwxyz
↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕↕
emwpjuyqdfhvscbkanrtxilozg

Using this alphabet we can convert a plain text message to an encrypted message by substituting the original letter for the cipher letter.

hello friend
↕↕↕↕↕↕↕↕↕↕↕↕
qjvvb undjcp

The process can be easily reversed, if you know the substitution alphabet.

There are several techniques used to read a message if you do not know the substitution alphabet. These include: counting letter frequencies, looking for common prefix and suffix patterns, looking for common digraph (two letter) pairs, trial and error, and looking for clues in the problem’s name.

What is a Crypto-Cross-Up?

A Crypto-Cross-Up is actually two cryptograms presented at the same time. The horizontal words have been encrypted with one substitution cipher and the vertical words have been encrypted with a different cipher. Letters that occupy the crossing points, in the puzzle, have the same substitution in both ciphers. This is a good place to start when deciphering the puzzle. Each puzzle is printed with a blank puzzle for you to fill in with the original words and an area where you can work on figuring out the cipher.

Each Crypto-Cross-Up has a name. The name is important. It will give you a clue about the words you are looking for in the puzzle. For example a puzzle named “Baseball” might contain team names, player positions, or words you might hear at a baseball game. All words will be connected to the puzzle name in some way.

Words in the puzzle may be proper nouns (names or places) and compound words. All words are written in lower case to make the search a little trickier. Punctuation and spaces in compound words are also removed. For example “Cincinnati Reds” would be “cincinnatireds” in the puzzle.

If you get totally stuck, there is a ‘hint’ available on the solutions page for each puzzle. This hint will tell you specifically how the words are related to the puzzle title. Once you know this, finding words that match the pattern of some of the encrypted words will expose letters on other words.

Playing the Crypto-Cross-Up On-line

This site includes a few puzzles that you can play for free online. When the puzzle is displayed, you may click on any letter in the ciphertext, plaintext, or the alphabet and enter the letter you believe it to be. It will be automatically updated throughout the plaintext and the alphabet.