Subject: Re: Differences between Kerbeors revisions and PKINIT

From: Jeffrey Altman <[email-masked]>
Date: Sat, 5 Aug 2000 2:14:34 EDT

> Isn't requiring the first bit of the "data" portion of the UTF-8 encoded
> character to be a 1 unless the character is decimal 127 or lower
> sufficient to catch those ambiguous invalid codings?  I thought the main
> reason why there were both legal and illegal sequences for the same
> character value was primarily because you can encode a character that
> would only take a single octet in six superficially-valid octets by making
> most of the data portion of the encoding 0 (for example).

I would have to go back and look at the code.  We implemented the UTF8
parser in Kermit over a year ago so things are not quite as fresh in
my mind.  :-)

Markus Kuhn's web site has more details on this.  As well as a good
selection of utf8 sample demonstrating the illegal inputs that must be
caught.  There are several variations.

> (Sorry for the digression; I just implemented UTF-8 support for wildmat
> matching for NNTP standardization support, so this is all fresh in my
> mind.)

How do you handle the matching of compatibility characters (identical
glyphs with different names at different code points that might be
interchanged by the user); or characters which can be represented as a
single character or as a base character and one or more combining
characters?

                  Jeffrey Altman * Sr.Software Designer
                 The Kermit Project * Columbia University
               612 West 115th St * New York, NY * 10025 * USA
     http://www.kermit-project.org/ * [email-masked]

---

From: Russ Allbery <[email-masked]>
Date: 05 Aug 2000 00:08:38 -0700

> single character or as a base character and one or more combining

I don't, currently.  Thankfully, for NNTP, it's probably not necessary.
wildmats are used mostly to match newsgroup names, where it's going to be
very clear in the standard that software treats newsgroup names as byte
strings in a lot of circumstances and therefore hierarchy administrators
have to pick a single "spelling" and stick with it everywhere, or things
like names in From addresses, Subject lines of threads, or other similar
places where while there may be alternate "spellings" of the words, one
generally only cares about one at a time since software preserves the
"spelling" on followups / only uses one all the time / etc.

-- 
Russ Allbery ([email-masked])             <http://www.eyrie.org/~eagle/>