Ciphers

Codes require a codebook. Ciphers do not.

Morse Code

Until the early 1920s, radio transmissions were in Morse Code, not voice. Dots and dashes make it a binary code like the 0’s and 1’s used in electronics. Each letter has a signal based on its frequency in English. The code tree begins with E with one dot, and T with one dash.

Code Tree

Morse Codebooks were used to lower the cost of sending telegrams, or to keep the contents a secret. Instead of sending a whole phrase or sentence, a single word could be used. If you want to hear a message in Morse Code, the Morse Code translator is a great place to visit. You can type in a message, translate it to Morse Code, and play it.

Signalling in Cipher

Union Army cipher disk

More info

Both armies in the Civil War used cipher disks like the one pictured above which allowed messages to be easily encoded and decoded. There was a standard flag code that gave each letter a numerical combination of 1s, flag right and 2s, flag left. Cool animation here

Freemason’s Cipher or Masonic Cipher

The Freemason’s Cipher has been around a long time. It was used in the American Civil War to send secret messages.  It is also sometimes called the Pigpen Cipher. Read more history here. Try an interactive online here.

http://crypto.interactive-maths.com/pigpen-cipher.html

Caesar Cipher

More info

The Caesar Cipher is a simple shift cipher. Each letter in the original message, plaintext, is shifted a specific number of positions in the alphabet to create the ciphertext. Encode/decode here.

  • The shift key is two. (Plaintext)
  • Vjg ujkhv mga ku vyq. (Ciphertext)

Vigenère Cipher

More Info  The widget here explains how it works.  The decoder here is fun.

You start with a table of shifting alphabets:

http://www.dcode.fr/vigenere-cipher

Add to that a Key word that is repeated the length of the plaintext message. The letter from the Key begins each row, the letter in the message each column. “GREAT FUN” becomes “JLFOB XXH” when encoded with DUBOIS as the Key.  Try it yourself, or go here and the computer will do it for you.

From teacher to writer, in 500 weeks or less.