In <200106271429(_dot_)KAA01122(_at_)astro(_dot_)cs(_dot_)utk(_dot_)edu> Keith
Moore <moore(_at_)cs(_dot_)utk(_dot_)edu> writes:
2. That there should only be ONE way to encode a given domain name (or
local-part, for that matter).
it's very likely that things will end up this way, for the simple reason
that folks don't want to break existing DNS servers and caches. so
even though there might be multiple ways to encode a non-ascii domain name
in Unicode (say, using combining and non-combining characters), after
canonicalization and ascii-encoding these should all fold to the same
representation.
Yes, but what I had in mind was that, even after you had normalized the
domain name according to the Unicode rules plus the IDN rules, you could
still land up with a domain name like
#(_at_)$*#$Q*$Q(_dot_)foo(_dot_)ch
(where #(_at_)$*#$Q*$Q is some chinese characters, but the rest in in ASCII,
and my apologies if 'ch' is not china). Now that has to be encoded to fit
within an RFC 2822 addr-spec. The question is: Do you encode just the
non-ASCII bits of it, or do you encode the whole lot, of can you choose
several ways, for example (using a fairly obvious hex encoding just to
illustrate the point):
=2340242a2324512a2451=.foo.ch
or =2340242a2324512a24512e666f6f=.ch
or =2340242a2324512a24512e666f6f2e6368=
Those might all pass through mailing systems (possibly morphing along the
way) and arrive at the correct destination, but any digital signature
which included them would break, unless one of them is declared to be the
canonical form.
Another long-term solution to all this, of course, is to use UTF-8 in mail
headers, and then the whole problem goes away (so far as mail is concerned
- the DNS might still need to be fixed). But that solution is not
immediately available (sendmail would break, for a start). However, Ned
did say some while back that he would work on UTF-8 in mail headers,
presumably as an extension to RFC 2821. Is that still his intention?
--
Charles H. Lindsey ---------At Home, doing my own thing------------------------
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