C is for Cipher

C is for Cipher

Ciphers. Codes. Carrier pigeons. They all hint at mystery and intrigue. We’re going to skip over the carrier pigeons for today, but it’s a fascinating topic that I definitely recommend looking into sometime!

Let’s start with what codes and ciphers are. Both are ways to send secret messages, but do you know the difference between the two? Did you know there was a difference between them? Many people don’t and use the two words interchangeably, but they aren’t quite the same thing. 

One definition says a cipher is a “method in which the basic unit of concealment is the the letter. In comparison, a code is a form of concealment in which the basic unit is the word.” (David E. Newton, Encyclopedia of Cryptology)


Codes replace words with other words. An easy example is to think about code names. Instead of using your real name, you might call yourself Dark Eagle or Mango Man in order to conceal your identity. Code names and phrases are often used in correspondance to protect a letter’s real meaning from anyone who interecepts it. Corrie ten Boom, whose family helped many people during the Holocaust, received a note in prison saying, “all the watches in your cabinet are safe.” Since watchmaking was her family’s business, this word wouldn’t arouse suspicion, but indicated to her that the people they were helping were all right.

(You can read more about this in Corrie ten Boom’s book, The Hiding Place.) 

c is for ciphers and codes for kids


Instead of substituting words, ciphers replace individual letters with different letters or symbols. Sometimes these ciphers are then additionally scrambled to make them especially card to decipher. 

The simplest cipher is one called a shift cipher. You’ve probably seen one of these before. Each letter of the alphabet is “shifted” over one or more places, and the reader needs to know how much to shift over in order to uncover the message. For instance:

A = D 
B = E
C = F

and so on.

Morse Code is not actually a code, and there are debates over whether or not it’s a cipher. Some say it’s a substitution cipher, while others espouse that’s it an encoding system and not a cipher, due to the key being public. What do you think?

Check out the awesome resources linked below, then send an encrypted message to a friend and see if they can crack it. Don’t forget to include the key!

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