Today’s Wonder of the Day was inspired by Keaton from Lake Wales. Keaton Wonders, “What is the Ceaser Cipher?” Thanks for WONDERing with us, Keaton!

Would you know what to do with a message that read, “Dwwdfn dw gdzq”? How about “Uhwuhdw”? Do those make any sense to you? No? Of course not! They were written using a Caesar Cipher.

The Caesar Cipher is a basic technique for encryption. It substitutes certain letters of the alphabet for others so that words aren’t immediately recognizable. Named for Julius Caesar, a Roman emperor who used it, the Caesar Cipher is also called the Caesar Shift or Shift Cipher.

How does a Caesar Cipher work? It’s easier than you might think! To encrypt a message, you start by listing the letters of the alphabet. Then, you’ll list the letters again right next to the first list. But first, you decide on a shift value. The shift value determines which letter the second list starts with.

For example, the messages above were written with a shift value of three. That means, instead of starting the second list with the letter “A,” we shifted down three letters, to the letter “D.” It looked like this:

A   D

B   E

C   F

D   G

...and so on.

Once you’ve listed the alphabet a second time, you’re ready to write messages. Each time you would use a letter on the left list, you substitute the letter on the right. So you would substitute “D” for “A,” “E” for “B,” and so on for the rest of the alphabet.

So, in this example, “Dwwdfn dw gdzq” means “Attack at dawn.” Can you figure out what “Uhwuhdw” is? That’s right, it means “Retreat”! Early Caesar Cipher messages were used often by ancient militaries. These are messages they could have actually sent!

Today, the Caesar Cipher has another use. If you use the Internet at home or school, you already know that people send a lot of information over the Internet every day. And plenty of that information—like passwords, social security numbers, and debit card numbers—need to be kept safe. This is done using encryption.

The Caesar Cipher is just one method of encryption, and it’s a fairly simple one. Websites responsible for personal data use much more advanced encryption techniques. However, young programmers often learn the basics of encryption using the Caesar Cipher

The Caesar Cipher might be a pretty basic encryption technique, but it’s still fun to use! Do you have any secret messages to send? How long do you think it would take someone to crack a Caesar Cipher? Give it a try! You never know what sensitive information you may need to protect.

Standards: NGSS.PS4.C, CCRA.R.4, CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.10, CCRA.W.2, CCRA.W.9, CCRA.L.1, CCRA.L.2, CCRA.W.4, CCRA.SL.1

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