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Posted by on May 6, 2020 in TellMeWhy |

What Is a Caesar Cipher? How Is It Used Today?

What Is a Caesar Cipher? How Is It Used Today?

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.

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, with a shift of 1, A would be replaced by B, B would become C, and so on. Julius Caesar, apparently used it to communicate with his generals.

Caesar cipher is a very simple encryption method and is easily cracked if one studies the frequency of repeating letters. To improve the strength of the encryption method a more complex key could be used.

Instead of shifting by 1, a pattern of shifts could be used: For example, 1,4,5,1. This pattern would be repeated and would be more difficult to crack using frequency analysis. Mathematically, using a simple shift of 1 means a character can be 1 of 26 possibilities. Using a key with 4 parts, a character can now be one of 26 * 26 * 26 * 26 = 456976 combinations. Much more difficult to crack!

pattern of shift value

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!

Content for this question contributed by Brian Brogan, resident of Cincinnati, Hamilton County, Ohio, USA