Re: [idn] stringprep comment 6: casefold and then noramlization is not enough

["Soobok Lee" <lsb@postel.co.kr>]

----- Original Message ----- 
From: "David Hopwood" <david.hopwood@zetnet.co.uk>
To: <idn@ops.ietf.org>
Sent: Tuesday, February 12, 2002 6:23 PM
Subject: Re: [idn] stringprep comment 6: casefold and then noramlization is not enough


> -----BEGIN PGP SIGNED MESSAGE-----
> 
> Soobok Lee wrote:
> > As I and David Hopwood suggested in the list,
> > 
> >   NFC(casefold(x)) or NFKC(casefold(x)) are not correct for <I dot above>
> > and <I><dot above>.
> 
> I suggest that the detail of this should be discussed on the
> unicode@unicode.org list.
> 
> Suffice it to say that it would be irresponsible to proceed with publication
> of the stringprep or nameprep draft just yet. 

I agree.

> I intend to propose a
> replacement for stringprep/nameprep that is simpler, more efficient, and
> that takes account of all the comments that have been made (including
> Hangul normalisation, BiDi, and spoofing, but excluding TC/SC).

Cheers!  I will help you  anytime if you want my aids. :-)


> 
> > The steps for preparing strings are:
> > 
> > 1) Map -- For each character in the input, check if it has a mapping
> > and, if so, replace it with its mapping. This is described in Section 4.
> > 
> > 2) Normalize -- Possibly normalize the result of step 1 using Unicode
> > normalization. This is described in Section 5.
> > 
> > 3) Look for prohibited output -- Check for any characters that are not
> > allowed in the output. If any are found, return an error. This is
> > described in Section 6.
> > 
> > The above steps MUST be performed in the order given to comply with this
> > specification."
> > 
> > Please suggest a proof that this last enforcement is necessary and sufficient.
> > 
> > I suggest the last "MUST" be changed to "MAY".
> 
> That would make the problem worse.

Maybe. It's clear that many changes should be made.
As suggested by many contributers, *more steps* should be introduced and interposed.

Soobok Lee