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How to Solve Ciphers

A cipher is a method of writing secret messages, using a code to encrypt the text. There are many different types of ciphers, and a good detective should be familiar with as many as possible to give them the best chance of deciphering any encoded message they may encounter.

No one is born knowing how to go about decoding these ciphers, so we've put together some handy guides for all our detectives.

If you know what cipher it is you're dealing with, click below. Otherwise carry on reading to discover some tips on how to decode basic messages or determine what type of cipher has been used.

General Tips for Deciphering Messages

Firstly, you should look for any words that might imply the kind of cipher you’re dealing with, e.g. shift, substitution, rail etc. If you can identify the type of cipher you're dealing with, you'll be able to use the best methodology to solve it.

Next, you should look for any hints to the alphabet that might have been used. For example, if the cipher uses symbols instead of letters, how many symbols are used - if it’s 26 then it’s probably just the alphabet, if it’s 36 then you are probably dealing with the alphabet plus numbers.

Look for a possible key. If you’re dealing with a Vigenere cipher, then you will need to identify what the key is. Are there any highlighted or underlined phrases or any references to specific sections of a book, website or other text?

Look for the characters that are written most often - this of course will only work with ciphers where the alphabets are fixed. However, it’s useful to know that the most common letters in English are, in order: E, T, A, O, I, N. You can read more about the most common letters and words on our Substitution Cipher page.

Is the text written in one long string, or are there spaces between, indicating words? Are there apostrophes? If so you can begin to guess that any single letter words are either A or I and that the letters after apostrophes are most likely S, T, D, M, LL, or RE.