caesarcipher.py

import string

def encrypt(message, shift):
    """
    Encrypts a message using the Caesar Cipher.
    Each letter is shifted forward by the shift amount.
    Numbers and symbols are left unchanged.
    """
    result = ""
    
    # Loop through every character in the message
    for char in message:
        
        # If it's an uppercase letter
        if char.isupper():
            # ord() converts a character to its ASCII number
            # e.g. ord('A') = 65, ord('Z') = 90
            # We subtract 65 to get 0-25, add shift, use % 26 to wrap around
            # then add 65 back to get the ASCII number of the new letter
            shifted = (ord(char) - 65 + shift) % 26 + 65
            result += chr(shifted)  # chr() converts ASCII number back to character
        
        # If it's a lowercase letter
        elif char.islower():
            # Same process but lowercase starts at ASCII 97
            shifted = (ord(char) - 97 + shift) % 26 + 97
            result += chr(shifted)
        
        # If it's a number, symbol, or space — leave it unchanged
        else:
            result += char
    
    return result

def decrypt(message, shift):
    """
    Decrypts a Caesar Cipher message.
    Decrypting is just encrypting with the opposite shift!
    """
    return encrypt(message, -shift)

def brute_force(message):
    """
    Tries all 25 possible shifts and prints them all.
    This is how a hacker would crack a Caesar Cipher —
    since there are only 25 possibilities, you can try them all instantly.
    This is why Caesar Cipher is not secure by modern standards!
    """
    print("\n🔓 BRUTE FORCE — All possible decryptions:")
    print("-" * 50)
    for shift in range(1, 26):
        attempt = decrypt(message, shift)
        print(f"Shift {shift:2d}: {attempt}")
    print("-" * 50)

def get_gandalf_reaction(mode):
    """
    Gandalf reacts to what you're doing in character.
    """
    if mode == "encrypt":
        reactions = [
            "🧙 'Clever! Even the Eye of Sauron could not read this!'",
            "🧙 'Your message is now hidden, like the entrance to Moria!'",
            "🧙 'Excellent! A secret worthy of the White Council!'",
        ]
    elif mode == "decrypt":
        reactions = [
            "🧙 'The message reveals itself, like dawn breaking over Mordor!'",
            "🧙 'Ah, the secret is laid bare! Knowledge is power, my friend!'",
            "🧙 'Like the inscription on the One Ring — all things are revealed in time!'",
        ]
    else:
        reactions = [
            "🧙 'We try all paths, like searching every passage in Moria!'",
            "🧙 'Brute force — not elegant, but effective. Even I am not above it!'",
            "🧙 'A wizard tries every door until one opens!'",
        ]
    
    import random
    return random.choice(reactions)

def main():
    print("🧙 GANDALF'S CAESAR CIPHER TOOL")
    print("=" * 50)
    print("*unrolls an ancient scroll and peers at it*")
    print("A most ancient form of secret communication...\n")

    while True:
        print("\nWhat would you like to do?")
        print("1. Encrypt a message")
        print("2. Decrypt a message")
        print("3. Brute force crack a message")
        print("4. Quit")
        
        choice = input("\nEnter your choice (1-4): ").strip()

        if choice == "1":
            message = input("\nEnter your message: ")
            
            while True:
                try:
                    shift = int(input("Enter shift amount (1-25): "))
                    if 1 <= shift <= 25:
                        break
                    print("Please enter a number between 1 and 25!")
                except ValueError:
                    print("Please enter a valid number!")
            
            encrypted = encrypt(message, shift)
            print(f"\n🔐 Original:  {message}")
            print(f"🔒 Encrypted: {encrypted}")
            print(f"🔑 Shift key: {shift}")
            print(f"\n{get_gandalf_reaction('encrypt')}")

        elif choice == "2":
            message = input("\nEnter encrypted message: ")
            
            while True:
                try:
                    shift = int(input("Enter shift amount (1-25): "))
                    if 1 <= shift <= 25:
                        break
                    print("Please enter a number between 1 and 25!")
                except ValueError:
                    print("Please enter a valid number!")
            
            decrypted = decrypt(message, shift)
            print(f"\n🔒 Encrypted: {message}")
            print(f"🔓 Decrypted: {decrypted}")
            print(f"🔑 Shift key: {shift}")
            print(f"\n{get_gandalf_reaction('decrypt')}")

        elif choice == "3":
            message = input("\nEnter message to brute force: ")
            print(get_gandalf_reaction('brute_force'))
            brute_force(message)

        elif choice == "4":
            print("\n🧙 'Keep your secrets well, and trust them only to the worthy. Farewell!'")
            break

        else:
            print("❌ Invalid choice — even Gandalf needs clear instructions!")

if __name__ == "__main__":
    main()