Caesar Cipher

The Caesar Cipher is a simple encryption technique that shifts each letter in a message by a fixed number of positions down the alphabet. It's named after Julius Caesar, who allegedly used it to communicate secretly.

How It Works

1. Alphabet Definition:

   • We define an alphabet containing uppercase and lowercase letters: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.

2. Encryption (Shift Right):

   • To encrypt a message, we shift each letter by a specified key value to the right (positive shift).
   • Non-alphabetic characters (such as spaces or punctuation) remain unchanged.

3. Decryption (Shift Left):

   • To decrypt a ciphertext, we shift each letter by the negative of the key value (leftward shift).

Usage

1. Encrypt:

   • Call the encrypt function with a positive key value and the plaintext you want to encrypt.
   • Example: encrypt(3, "HELLO") results in "KHOOR".

2. Decrypt:

   • Call the decrypt function with the negative of the key value and the ciphertext you want to decrypt.
   • Example: decrypt(3, "KHOOR") results in "HELLO".

Example

# Encrypt
encrypted_text = encrypt(5, "SECRET MESSAGE")
print("Encrypted:", encrypted_text)  # Output: "XJHWJY RJXXFLJ"

# Decrypt
decrypted_text = decrypt(5, encrypted_text)
print("Decrypted:", decrypted_text)  # Output: "SECRET MESSAGE"

Feel free to experiment with different keys and messages! 🗝️🔒