Lesson Plan: Creating a Caesar Cipher

Lesson Overview

In this lesson, students will learn about the Caesar cipher, a simple encryption technique. They will then implement their own Caesar cipher encoder and decoder using Python.

Learning Objectives

Implement a basic Caesar cipher in Python.
Encrypt and decrypt messages using their implementation.
Modify the cipher to incorporate the same cipher letters / numbers as before.

Lesson Structure

1. Pseudocode for Caesar Cipher (10 min)

Discuss the logic:

Choose a shift value.
Convert each letter to its ASCII value.
Shift the value and convert it back to a letter.
Handle uppercase and lowercase letters separately.
Preserve non-alphabetic characters (spaces, punctuation).

2. Implementing the Caesar Cipher in Python (20 min)

Step 1: Writing the encryption function

 def caesar_cipher_encrypt(text, shift):
  encrypted_text = ""
  for char in text:
  if char.isalpha():
 ********* missing Code *************
  Step 2: Writing the decryption function
   def caesar_cipher_decrypt(text, shift):
  return caesar_cipher_encrypt(text, -shift) 
  Step 3: Testing the functions
   message = "Hello, World!"
  shift_value = 3
  encrypted_message = caesar_cipher_encrypt(message, shift_value)
*************** missing Code *********************
  print(f"Decrypted: {decrypted_message}") 
  3. Enhancements & Challenges (15 min)
  
    Modify the function to allow for non-alphabetic character shifts.
    Add user input functionality.
    Create a function that brute-force decrypts a message (trying all 25 shifts).
    Implement a Caesar cipher using list comprehensions.
  
  4. Q&A and Wrap-up (5 min)
  
    Review key concepts.
    Discuss real-world applications of simple ciphers.
    Homework: Research frequency analysis and how it can be used to break the Caesar cipher.
  
  Assessment
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      You will drop off 4 files into Google Classroom:
			• Your files will be: (Remember the python program is dropped off first.)
			• PX_lastname_CeasarCipherPython.py (Actual Python code)
			• PX_lastname_CeasarCipherPython.png (Screenshot in the Cyber Range)
			• PX_lastname_CeasarCipherPython.txt (Source code as Text)
			• PX_lastname_CeasarCipherPython.mp4 (Video running the program)