Thanks for the info @trevnorris!

Regarding ```Buffer::Data()``` returning a ```char*```, it should look like this then?

```char* data = Buffer::Data(args[0]);
  if (data == NULL)
    return Undefined(node_isolate);

  int i = certificate->VerifySpkac(const_cast<const char*>(data), length);

  return Boolean::New(i > 0);```

I do appreciate all the help you and @bnoordhuis have been giving me