Re: [idn] stringprep comment 2

["Adam M. Costello" <idn.amc+0@nicemice.net.RemoveThisWord>]

Soobok Lee <lsb@postel.co.kr> wrote:

> 6. Unassigned Code Points in Stringprep Profiles
>
> This section describes two different types of strings in typical
> protocols where internationalized strings are used: "stored strings"
> and "queries".
>
> Is this classification from over-simplifications ? only two types?  Is
> there any 3rd type possible?

I think what this section really depends on is that whenever two strings
are compared, at least one of the strings must have been prepared using
strict stringprep (no unassigned code points allowed), while the other
may have been prepared using loose stringprep (unassigned code points
allowed).  This allows false negatives (where the strings don't match
even though you wish they did), but prevents false positives (where the
strings match even though they shouldn't).

Applications and protocols need to do whatever is necessary to guarantee
that whenever two strings are compared, at least one was prepared using
strict stringprep.  Typically they would satisfy that requirement by
classifying strings into "stored strings" and "query strings", using
strict stringprep on the stored strings, and never comparing two query
strings.  But it's up to each application/protocol to define that
classification for its own strings.

Perhaps the document should say something like that.

AMC