Caesar Cipher using Python

main.py

alphabet = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
            'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p',
            'q', 'r', 's', 't', 'u',
            'v', 'w', 'x', 'y', 'z']

direction = input("Type 'encode' to encrypt, type 'decode' to decrypt:\n")
text = input("Type your message:\n").lower()
shift = int(input("Type the shift number:\n"))


def encrypt(plain_text, shift_amount):
    cipher_text = " "
    for letter in plain_text:
        position = alphabet.index(letter)
        new_position = position + shift_amount
        new_letter = alphabet[new_position]
        cipher_text += new_letter
    print(f"The encrypted code is {cipher_text}")


encrypt(plain_text=text, shift_amount=shift)

# Decrypting cipher

alphabet = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u',
            'v', 'w', 'x', 'y', 'z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p',
            'q', 'r', 's', 't', 'u',
            'v', 'w', 'x', 'y', 'z']

direction = input("Type 'encode' to encrypt, type 'decode' to decrypt:\n")
text = input("Type your message:\n").lower()
shift = int(input("Type the shift number:\n"))


def decrypt(plain_text, shift_amount):
    decipher_text = " "
    for letter in plain_text:
        position = alphabet.index(letter)
        new_position = position - shift_amount
        new_letter = alphabet[new_position]
        decipher_text += new_letter
    print(f"The decrypted code is {decipher_text}")


decrypt(plain_text=text, shift_amount=shift)


# Reorganising the code
def caesar(start_text, shift_amount, cipher_direction):
    end_text = " "
    if cipher_direction == "decode":
        shift_amount *= -1
    for letter in start_text:
        position = alphabet.index(letter)
        new_position = position + shift_amount
        end_text += alphabet[new_position]
    print(f"The {cipher_direction}d is {end_text}")


caesar(start_text=text, shift_amount=shift, cipher_direction=direction)