IDNAbis -- must not miss I18N presentation
By nico on Aug 01, 2007
At last week's 69th IETF meeting (in Chicago) there was a presentation on the IDNAbis effort at the SAAG meeting on Thursday that anyone with an interest in I18N should look at and listen to (the presentation starts about 28 minutes into the recording).
For me the biggest takeaway is this: if you want Unicode version agnosticism, and you \*should\* want that, then you need to think carefully about where unassigned codepoints will be dealt with. In particular, IF you use ACE encoding on the wire in your protocols then you need only worry about Unicode versions supported at the client end -- a very important point. Of course, administrative authorities must be the ones to enforce rules about Unicode version use, and about use of codepoints heretofore considered dangerous, the latter in context- and language-specific ways (another crucial, and brilliant, insight in the IDNAbis presentation).
One of the attributes of the IDNAbis proposal is that a lot of constraints from stringprep would be relaxed significantly, to the point where we can, and should, consider the use of A-labels (meaning, the output of toASCII(), that is, punycoded strings), on the wire in critical protocol elements. In particular I'm thinking that Kerberos V I18N should just shove ACE into all instances of GeneralString in the protocol, augmented with UTF8String and OCTET STRING (for legacy names from just-send-8 deployments) aliases of principals and realm names to support migrations.