Mixing scripts (Re: Unicode versions (Re: Criteria forexceptional characters))

[Martin Duerst]

At 21:39 06/12/21, Soobok Lee wrote:

>Local character sets might provide  some clues.

Clues, yes, but not much more.

>They often contain
>multiple scripts in single local charset in order to serve the need
>of everyday language life of local language communities.
>
>I think this statement is very reasonable:
> "If it is possible to "localize" an IDN label in any single local charset,
>   the label should be allowed, however many scripts it spans across.
>   Even for some of those, UA can display in punycode form."

See more below for why this is a bad idea.

>Labels of Simplified Han Ideo + Hangul Syllables  cannot be
>typed in or displayed in either of KSC5601(Korea) and  GB2312(China).
>So they should be disallowed somewhere between IDNA,UA and registries.

The quoted statement above only says what should be allowed,
so I don't see how it follows that combinations of simplified
Han and Hangul should be disallowed. And there are quite a few
simplified Han that are indistinguishable from traditional Han
(and use just one codepoint),


>Greek local charset(iso-8859-7) does not contain any cyrillic char,
>Cyrillic local charset(iso-8859-5) does not contain any greek char.

Please do your homework and have another close look at your local
charset, KSC 5601.

Similar to JIS X 0208 and GB 2312, it contains not only (full-width
copies of ASCII) Latin, but also Greek and Cyrillic. Greek is
handy in math and physics, and Russia is close to all three
countries, and a few small alphabets didn't really take up
too much space besides the large number of Hanzi/Kanji/Hanja/Hangul.

So the idea of saying "if these appear in the same local charset,
they must be safe" is a very dangerous one. None of these charsets
have been tested with something as exposed to serious criminals
as domain names, and none of these charsets has been designed
with spoofing issues anywhere in mind.

Regards,    Martin.



#-#-#  Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University
#-#-#  http://www.sw.it.aoyama.ac.jp       mailto:duerst at it.aoyama.ac.jp