Caesar Cipher — Encrypt & Decrypt Text

An interactive Python implementation of the classic Caesar Cipher, letting you encrypt and decrypt messages with any shift value.

Overview

The Caesar Cipher is one of the oldest known encryption techniques: each letter in a message is shifted a fixed number of positions down the alphabet. This notebook implements both encryption and decryption with a simple interactive loop — enter a message and a shift value, and get the transformed text back.

Example from the notebook:

Would you like to (e)ncrypt or (d)ecrypt a message? (e/d): d
Enter your message: jgnnq aqw
Enter the shift value: 2
Decrypted message: hello you

How It Works

• caesar_cipher_encrypt(plaintext, shift) — shifts each alphabetic character forward by shift positions using modular arithmetic (% 26), preserving case
• caesar_cipher_decrypt(ciphertext, shift) — reverses the shift to recover the original message
• Uppercase and lowercase letters are handled independently, so case is preserved
• Any shift value works — shifts wrap around the alphabet thanks to the modulo operation
• An interactive main() loop lets you encrypt/decrypt repeatedly until you choose to quit

Tech Stack

• Python 3 — pure standard library, no external dependencies
• Jupyter Notebook (developed in Google Colab)

Getting Started

1. Clone the repository:

   git clone https://github.com/techieshreya/Encrypt-and-Decrypt-text-using-the-Caesar-Cipher-algorithm.git

2. Open encrypt_decrypt.ipynb in Jupyter Notebook or Google Colab.

3. Run the cell and follow the prompts to encrypt or decrypt your message.