Re: [idn] Re: Just send UTF-8 with nameprep

[Martin Duerst <duerst@w3.org>]

At 21:12 01/07/18 -0500, Eric A. Hall wrote:

>Any domain name which is entered as an IDN would need to have the IDN flag
>enabled, but must not have the legacy flag enabled. These IDNs must only
>be used to answer IDN queries, and must not be processed through legacy
>query paths, as they would likely be used to answer queries being issued
>by older applications in that scenario. We must not allow UTF-8 IDNs to to
>be processed by older applications, since they may be issuing queries
>based on a local encoding (such as 8859-n or windows-nnnn or MacRoman or
>whatever). Using these IDNs to answer legacy queries will absolutely
>definitely cause some kind of unintended consequence, and we will get a
>lot of heat for the failure.

The chance that when a legacy resolver passes through a local encoding
and this matches with a UTF-8 entry is extremely low. The reason for this
is that UTF-8 has a very peculiar byte pattern. For details, please see my
paper at
http://www.ifi.unizh.ch/mml/mduerst/papers/PDF/IUC11-UTF-8.pdf.

Regards,   Martin.