Scouts learn to use shift cyphers (also known as a Caesar cypher) to encode and decode messages.
- Encoded text
- Shift cipher code wheels (see attachments)
- Sample of encoded and decoded text.
Explain to Scouts that...
- A shift (or Caesar) cypher is one where each letter is replaced with another one.
- It's called a shift cypher because the whole alphabet shifts places to change the letters to new ones
- It was used by Roman general Julius Caesar!
- A computer could break it quite quickly, but a person may take a while if they don't know the key to solve it.
- A code wheel and keyword will help you encode and decode a message quickly.
- Show Scouts some scrambled cypher text.
- Scout Scouts a code wheel.
- Demonstrate that when you line up the code wheel right, it gives you the key to code or decode a message.
- Decode one or two words using the
- Guide Scouts through decoding a phrase or short message.
- Help Scouts to encode their own message (perhaps their name?) and exchange it with a friend to see if they can decode it.
- Questions to ask: Is it much harder without the keyword? Can we sometimes guess what the shift is based on common letters?