information-security-caesar-cipher

Caesar Cipher Encryption & Decryption (Python)

Project Description

This project implements the Caesar Cipher encryption and decryption algorithm using Python. It was developed as part of the Information Security Lab assignment (Spring 2026).

The Caesar Cipher is one of the oldest and simplest encryption techniques. It works by shifting each letter in a message by a fixed number of positions in the alphabet.

Example: HELLO (Shift 3) → KHOOR

Features

• Encrypts text using Caesar Cipher
• Decrypts encrypted text
• Maintains uppercase and lowercase letters
• Keeps spaces and special characters unchanged
• User input for message and shift value

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Technologies Used

• Python 3

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How to Run the Program

1. Make sure Python 3 is installed.
2. Download the .py file.
3. Run the program using:
4. Enter your message and shift value when prompted.

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Security Analysis

The Caesar Cipher is a substitution cipher with only 25 possible shift keys.
It is not secure against modern attacks because:

• It can be broken using brute-force easily.
• It is vulnerable to frequency analysis.
• The key space is very small.

However, it is useful for understanding basic cryptography concepts and modular arithmetic.

Author

Sayeda Aliza Hashmi
Software Engineering Student
COMSATS University Islamabad