text: from tools.crypto_helper import AES
  from tools.file_helper import read_base64_encoded_text_file
  
  def CBC_decrypt():
      file_bytes = read_base64_encoded_text_file("10.txt")
      key_bytes = bytes("YELLOW SUBMARINE", "utf-8")
      iv = bytes([0]*16)
  
      plain_bytes = AES.CBC.decrypt(cipher_bytes=file_bytes, key_bytes=key_bytes, iv=iv)
      # same lyrics as in challenge 7 !!
      print(plain_bytes.decode("utf-8"))
  
  if __name__ == "__main__":
      CBC_decrypt()
      print("End of program")
  