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curriculum/challenges/english/blocks/learn-string-manipulation-by-building-a-cipher/65552b14e803731fe3c1e4ca.md

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--description--

Next, modify your encryption and decryption variables by calling encrypt and decrypt, respectively, in place of vigenere.

--hints--

Your encryption variable should have the value of encrypt(text, custom_key).

js
({ test: () => assert.match(code, /^encryption\s*=\s*encrypt\s*\(\s*text\s*,\s*custom_key\s*\)/m) })

Your decryption variable should have the value of decrypt(encryption, custom_key).

js
({ test: () => assert.match(code, /^decryption\s*=\s*decrypt\s*\(\s*encryption\s*,\s*custom_key\s*\)/m) })

--seed--

--seed-contents--

py
text = 'Hello Zaira!'
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
--fcc-editable-region--
def encrypt(message, key):
    return vigenere(message, key)
    
def decrypt(message, key):
    return vigenere(message, key, -1)
    
encryption = vigenere(text, custom_key)
print(encryption)
decryption = vigenere(encryption, custom_key, -1)
print(decryption)
--fcc-editable-region--