Caesar Cipher

Caesar Cipher Project:

The Caesar cipher is an ancient encryption algorithm used by Julius Caesar. It encrypts letters by shifting them over by a certain number of places in the alphabet. We call the length of shift the key. For example, if the key is 3, then A becomes D, B becomes E, C becomes F, and so on. To decrypt the message, you must shift the encrypted letters in the opposite direction. 

Write a program that lets the user encrypt and decrypt messages according to this algorithm.

The Program in Action

When you run the program, the output will look like this:

PROGRAM START--

Do you want to (e)ncrypt or (d)ecrypt?

> e

Please enter the key (0 to 25) to use.

> 4

Enter the message to encrypt.

> Meet me by the rose bushes tonight.

QIIX QI FC XLI VSWI FYWLIW XSRMKLX.

PROGRAM START--

Do you want to (e)ncrypt or (d)ecrypt?

> d

Please enter the key (0 to 26) to use.

> 4

Enter the message to decrypt.

> QIIX QI FC XLI VSWI FYWLIW XSRMKLX.

MEET ME BY THE ROSE BUSHES TONIGHT.