Re: [idn] IDN spoofing

Philippe Verdy <vpi92 at yahoo dot fr> wrote:

> The bad thing about your argument is that you are trying to mix
> uppercase and uppercase letters. But for IDN, only lowercase letters
> are really made distinct and encodable, as uppercase letters are case
> folded to lowercase. So let's just concentrate on the set of letters
> that really are distinct in lowercase because this is the form where
> DNS servers will make distinctions in ASCII letters.

The equivalence of upper and lower case letter might become troublesome when
working with the Unicode set. For example, Latin and Greek "A" are equal.
Then this forces lowercase "a" and alpha top become equivalent, despite the
fact that no-one familiar with these scripts will confuse them. This example
is pretty easy, and for IDN's it only means that one cannot define an
equivalent name (there is no problem if there is another Greek/Latin
character separating the name), so one can perhaps live by it. But having
too much equivalences may make the name-separating semantics to collapse in
unwanted ways.

  Hans Aberg