Solving coded messages isn’t as hard as you think, but the reason why may surprise you. Most people assume that messages are encoded to obscure their meanings. But that’s only partially true. Messages are encoded to hide their contents from everyone but the recipient. In other words, the best coded messages are designed to be decoded, but only by the right person.

To solve a coded message, think about it as a lock. The key to solve a coded message is also called a key. The type of key to use depends on what kind of coded message you have. So the first step in solving any coded message is to figure out what kind of code is being used. Hints may come in the form of patterns, like repeated words or sets of numbers. Some types of coded messages include book ciphers, Ottendorf ciphers and bifid ciphers.

Solve a coded message by figuring out how it was written. Then, do those steps backward to reveal the original text.

How to Solve a Book Cipher

A book cipher is a type of cipher that uses a common book as its key text. People who pass messages using book ciphers choose common books for an added level of secrecy: No one will suspect anything strange is going on if two people have the same copy of a Harry Potter book. Two people possessing the same edition of an uncommon book looks much more suspicious.

To encode a message using a book cipher, first, choose a common book to use as your key text. Make sure the person you’re sending your coded message to also owns that book. Next, write your message out in plain language. Then grab a new sheet of paper, and open your book. Find words and phrases that correspond to parts of your original text. Write their placement in your book on your second sheet of paper. Write the placements in sets of numbers that indicate where in the book to find those phrases. These number sets will include a number for the page, the paragraph and the line of the word. Separate each by a comma, and put the set in parentheses or brackets so things don’t get confusing.

Though book ciphers have the word “book” in their name, any other common piece of text can be used as well. Just be sure that you and the recipient of your message have the same version of the text. Otherwise, your page and line numbers might not be the same, and your cipher won’t work!

How to Solve an Ottendorf Cipher

An Ottendorf cipher is like a book cipher but more intricate. An Ottendorf cipher is the best kind of cipher to use if you’re writing a message with uncommon words or proper nouns because Ottendorf ciphers are coded down to the level of individual letters.

To create an Ottendorf cipher, follow the same steps you would to create a book cipher. But instead of stopping at the word level, go one step further. Each four-number numerical set you write will indicate the page, line, word and letter in that word necessary to decipher the code.

Other Types of Coded Message

Other types of coded messages include bifid ciphers, shift ciphers, substitutions and more. To solve any coded message, use the same technique. First, determine what type of coded message it is. That is your lock. Now figure out the key.