IDNA2008: concerns about inconsistent mappings, and german sharp s

Alireza Saleh saleh at nic.ir
Thu Dec 11 07:29:36 CET 2008


Dear Markus,

We have the same problem for Arabic-Script character ZWNJ ( Zero With 
Non-Joiner ) . IDNA2003 says that this character should be removed 
before generating the A-label.  But in IDNA2008, this character 
categorized as CONTEXT because its unicode's property is 'joining'. As 
it is a necessary character for some languages using Arabic-script, it 
is possible for us to define a safe contextual rule for it and use it in 
IDN lables. Without having a contextual rule, IDNA2008 treats the same 
as IDNA2003 in case of ZWNJ. I don't know if it is possible to propose 
the same solution for 'eszett' and the other mapping characters.

Alireza


Markus Scherer wrote:
> Dear IDNA-updaters,
>
> I recently learned about some details about IDNA2008 and was 
> encouraged to voice concerns on this list.
>
> If I understand correctly, IDNA2008 -- unlike the 2003 version -- will 
> not prescribe a particular set of character mappings. I am concerned 
> that this will lead to implementations behaving inconsistently, and, 
> for users, unpredictably, leading to navigation to the wrong web sites 
> or getting an error message for what seems like (and used to be) a 
> minor variation (for example, a casing difference).
>
> In particular, as a native German speaker, I am concerned about what I 
> understand to be the effect on using German domain names -- regarding 
> the '�' ("sharp s", also mis-named "eszett").This character is mostly 
> equivalent to "ss", and normal uppercasing turns it into "SS" (except 
> maybe on passports). Because of this near-equivalence, there is some 
> amount of confusion about when to use "�" vs. "ss". In particular,
>
>     * In Switzerland, "�" is never used and always replaced with "ss".
>     * The orthography change of 1996 changed the rules about � vs. ss
>       and changed many very common words. Anyone who learned to write
>       before the reform (like me) is prone to either still write the
>       old way or be inconsistent, in addition to normal
>       spelling imperfections.
>     * For several years, prominent newspapers and publishers refused
>       to adopt the new orthography or flip-flopped in their adoption.
>
> The old IDNA standard mapped "�" to "ss". I understand that IDNA2008 
> does not include this mapping (or indeed any other), but does permit � 
> in unmapped domain names. This means that it will be possible for 
> equivalent domain names (flu�.de <http://fluss.de> vs. fluss.de 
> <http://fluss.de>) which used to be mapped to the same form (fluss.de 
> <http://fluss.de>) to now point to unrelated web sites (where one 
> might be a phishing site mimicking the other), or a user who used to 
> be successful following a link "flu�.de <http://fluss.de>" may now 
> find that their browser fails to connect.
>
> Please review this decision!
>
> It seems like for best consistency and interoperability, the updated 
> IDNA standard should include mappings that are compatible extensions 
> of the 2003 version, except to fix errors and security issues, and in 
> particular should maintain the folding of equivalent domain names to a 
> common representative.
>
> Failing that, it would help to continue to not allow the "�" in domain 
> names, except as input to an implementation which maps it to "ss" as 
> before.
>
> If that were not adopted either, then users can only hope that all 
> registrars either automatically treat all equivalent forms as aliases 
> or forbid registering a domain name if an equivalent one exists 
> already. (A connection error would be better than a phishing trap.) I 
> am pessimistic about all relevant registrars to learn about this (or 
> anything that's not required by the spec), understand it, and apply it 
> consistently.
>
> Sincerely,
> markus
>
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