[idn] Fast nameprep vs. slow nameprep

["D. J. Bernstein" <djb@cr.yp.to>]

Patrik writes:
> With the introduction of IDN, we can no longer "just" edit the config 
> files in whatever applications.

The worst case---for places like Japan, where we've heard that you can't
even type a dot without special effort---is that the operating system
needs ONE domain-name-typing tool as part of the keyboard interface.

I'm explicitly assuming that we _won't_ allow names needing nameprep in
configuration files. Bad names disappear as soon as they leave the
keyboard. That's fast nameprep. The changes are isolated inside the
keyboard interface.

You're implicitly assuming that we _will_ allow names needing nameprep
in configuration files. That's slow nameprep. It's horribly expensive.
Hundreds of programs will need to learn about nameprep.

---Dan