Caesar Cipher

This project provides a simple, robust implementation of the Caesar cipher in Python. The Caesar cipher is a classic encryption technique that shifts each letter in the plaintext by a fixed number of positions in the alphabet.

Features

• Encrypt and decrypt messages using a shift value
• Preserves case (uppercase/lowercase)
• Non-alphabetic characters are not changed
• Command-line interface for easy use
• Well-structured, type-annotated code

Usage

Command Line

python caesar.py enc 3 "Meet me at 10"
python caesar.py dec 3 "Phhw ph dw 10"

• enc: Encrypt the message
• dec: Decrypt the message
• 3: The shift amount (can be any integer)
• The text must be in quotes if it contains spaces

Example

Encrypt:

python caesar.py enc 5 "Hello, World!"
# Output: Mjqqt, Btwqi!

Decrypt:

python caesar.py dec 5 "Mjqqt, Btwqi!"
# Output: Hello, World!

Module Usage

You can also import and use the cipher in your own Python code:

from caesar import caesar_cipher

encrypted = caesar_cipher("Secret Message", 4)
decrypted = caesar_cipher(encrypted, -4)
print(encrypted)  # Output: Wigvix Qiwweki
print(decrypted)  # Output: Secret Message

Requirements

• Python 3.6 or higher
• No external dependencies

License

See LICENSE for details.