# Caesar Cipher

The Caesar cipher is one of the simplest and best-known encryption techniques. It is a substitution cipher that operates by shifting the letters of the alphabet a certain number of positions to encrypt and decrypt messages. This cipher is named after Julius Caesar, who is said to have used it for communication.

In the Caesar cipher:

- Each letter of the alphabet is shifted by a fixed number of positions.
- For example, with a shift of 3, 'A' becomes 'D', 'B' becomes 'E', 'C' becomes 'F', and so on.
- The shifting wraps around, so 'Z' becomes 'C', and 'Y' becomes 'B'.
- Non-alphabetic characters, such as spaces or punctuation, remain unchanged.

The number of positions shifted is often referred to as the "key" or "shift value" of the cipher. It determines the amount by which each letter is shifted.

Here's an example of encrypting the message "HELLO" with a Caesar cipher and a shift of 3:

- 'H' becomes 'K'
- 'E' becomes 'H'
- 'L' becomes 'O'
- 'L' becomes 'O'
- 'O' becomes 'R'

So, "HELLO" would be encrypted as "KHOOR" using a Caesar cipher with a shift of 3.

To decrypt a message encrypted with a Caesar cipher, you perform the reverse operation. You shift each letter in the opposite direction by the same number of positions to retrieve the original message.

The Caesar cipher is a straightforward and easily understood encryption technique. However, due to its simplicity, it is considered a weak cipher and can be easily deciphered through brute force or frequency analysis.

Despite its lack of security, the Caesar cipher serves as a foundation for more complex encryption algorithms and provides a starting point for learning about cryptography.