code: def _prep_crypto_msg(message):
      
      signature = message['signature']
      certificate = message['certificate']
      sliced_signature, sliced_certificate = [], []
      for x in range(0, len(signature), 76):
          sliced_signature.append(signature[x:x+76])
      for x in range(0, len(certificate), 76):
          sliced_certificate.append(certificate[x:x+76])
  
      message['signature'] = u'\n'.join(sliced_signature) + u'\n'
      message['certificate'] = u'\n'.join(sliced_certificate) + u'\n'
      return message
docs: Split the signature and certificate in the same way M2Crypto does.
  
      M2Crypto is dropping newlines into its signature and certificate. This
      exists purely to maintain backwards compatibility.
  
      Args:
          message (dict): A message with the ``signature`` and ``certificate`` keywords.
              The values of these two keys must be byte strings.
  
      Returns:
          dict: The same message, but with the values of ``signature`` and ``certificate``
              split every 76 characters with a newline and a final newline at the end.