Learn String Manipulation by Building a Cipher - Step 83

Tell us what’s happening:

Describe your issue in detail here.

How is it that the expected output is the orignal text for the encryption print() statement?

if the original text is such that → text = ‘mrttaqrhknsw ih puggrur’, why do we also expect the encrypted output to be :

encryption = encrypt(text, custom_key)
print('Encrypted text: ’ + encryption)

Expected output :
Encrypted text: mrttaqrhknsw ih puggrur (which is wrong if we are encrypting )

Your code so far

text = 'mrttaqrhknsw ih puggrur'
custom_key = 'python'

def vigenere(message, key, direction=1):
    key_index = 0
    alphabet = 'abcdefghijklmnopqrstuvwxyz'
    final_message = ''

    for char in message.lower():

        # Append any non-letter character to the message
        if not char.isalpha():
            final_message += char
        else:        
            # Find the right key character to encode/decode
            key_char = key[key_index % len(key)]
            key_index += 1

            # Define the offset and the encrypted/decrypted letter
            offset = alphabet.index(key_char)
            index = alphabet.find(char)
            new_index = (index + offset*direction) % len(alphabet)
            final_message += alphabet[new_index]
    
    return final_message

def encrypt(message, key):
    return vigenere(message, key)
    
def decrypt(message, key):
    return vigenere(message, key, -1)

/* User Editable Region */

encryption = encrypt(text, custom_key)
print('Encrypted text: ' + encryption)
decryption = decrypt(encryption, custom_key)
print(decryption)

/* User Editable Region */

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Challenge Information:

Learn String Manipulation by Building a Cipher - Step 83

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Hello Tumishang,

They are building up to making the decrypt function to work as you would except. You will see it in the following excersises. It just takes a bit to get there.

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