Need to decrypt an AES encrypted string that was encrypted in flutter https://pub.dev/packages/encrypt

Questions / Help
3

Thanks for the reply ChristopheBelpaire,

does the iv argument have to be binary when given to the one_time function and the key can be a string?
because when i try Base.decode16! the key i get (ArgumentError) non-alphabet digit found: “%” as that how other Help with crypto module - crypto_one_time method - (ArgumentError) argument error Issue - #2 by NobbZ users have done

  # Use AES 128 Bit Keys for Encryption.
  @block_size 16

  def encrypt(plaintext) do
    # create random Initialisation Vector
    iv = "}Lq5Wu~nkr\Vdfm~"
    # sample secret_key is a 32 bit hex string
    secret_key = "%8R=&PfC5SXT:pRF2vF[5zCTy}M7CX]J"
    plaintext = pad(plaintext, @block_size)
    encrypted_text = :crypto.crypto_one_time(:aes_128_cbc, secret_key, iv, plaintext, true )
    encrypted_text = ( iv <>  encrypted_text )
    :base64.encode(encrypted_text)
  end

  def decrypt(ciphertext) do
    secret_key = "%8R=&PfC5SXT:pRF2vF[5zCTy}M7CX]J"
    ciphertext = :base64.decode(ciphertext)
    <<iv::binary-16, ciphertext::binary>> = ciphertext
    decrypted_text = :crypto.crypto_one_time(:aes_128_cbc, secret_key, iv, ciphertext, false )
    unpad(decrypted_text)
  end

  def unpad(data) do
    to_remove = :binary.last(data)
    :binary.part(data, 0, byte_size(data) - to_remove)
  end

# PKCS5Padding
  def pad(data, block_size) do
    to_add = block_size - rem(byte_size(data), block_size)
    data <> :binary.copy(<<to_add>>, to_add)
  end
end