Python Message Encrypter

About This Project

The Python Message Encrypter is a project that demonstrates different encryption techniques used to secure messages. This is a great beginner project for learning about string manipulation, cryptography basics, and Python functions.

Encryption Methods

1. Caesar Cipher

Shifts each letter by a fixed number of positions in the alphabet. Named after Julius Caesar who used it for military communications.

2. ROT13

A special case of Caesar cipher with a fixed shift of 13. Since the alphabet has 26 letters, ROT13 is its own inverse.

3. Reverse Cipher

Simply reverses the entire message. A simple but effective method for basic obfuscation.

4. Base64 Encoding

Converts binary data to ASCII text. Not encryption, but commonly used to encode data for transmission.

Source Code

# Python Message Encrypter
# Demonstrates different encryption techniques

import base64

def caesar_cipher(text, shift):
    result = ""
    for char in text:
        if char.isalpha():
            ascii_offset = 65 if char.isupper() else 97
            result += chr((ord(char) - ascii_offset + shift) % 26 + ascii_offset)
        else:
            result += char
    return result

def rot13(text):
    return caesar_cipher(text, 13)

def reverse_cipher(text):
    return text[::-1]

def base64_encode(text):
    return base64.b64encode(text.encode()).decode()

def base64_decode(text):
    return base64.b64decode(text.encode()).decode()

def main():
    print("Python Message Encrypter")
    print("1. Caesar Cipher")
    print("2. ROT13")
    print("3. Reverse Cipher")
    print("4. Base64 Encode")
    print("5. Exit")
    
    while True:
        choice = input("\nSelect option: ")
        
        if choice == '1':
            text = input("Enter message: ")
            shift = int(input("Enter shift (1-25): "))
            print(f"Encrypted: {caesar_cipher(text, shift)}")
        
        elif choice == '2':
            text = input("Enter message: ")
            print(f"Encrypted: {rot13(text)}")
            print(f"Decrypted: {rot13(rot13(text))}")
        
        elif choice == '3':
            text = input("Enter message: ")
            print(f"Encrypted: {reverse_cipher(text)}")
            print(f"Decrypted: {reverse_cipher(reverse_cipher(text))}")
        
        elif choice == '4':
            text = input("Enter message: ")
            encoded = base64_encode(text)
            print(f"Encoded: {encoded}")
            print(f"Decoded: {base64_decode(encoded)}")
        
        elif choice == '5':
            break

if __name__ == "__main__":
    main()

Example Output

Input: "Hello World"

Caesar (shift 3): "Khoor Zruog"

ROT13: "Uryyb Jbeyq"

Reverse: "dlroW olleH"

Base64: "SGVsbG8gV29ybGQ="

Learning Objectives

Understand basic string manipulation in Python
Learn about ASCII and character encoding
Implement functions for encryption algorithms
Work with the base64 module
Handle user input and menu-driven programs