Comments on draft-ietf-idnabis-defs-10

James Mitchell james.mitchell at ausregistry.com.au
Mon Aug 31 01:29:21 CEST 2009


Punycode encode copies all ASCII characters verbatim;  all U-labels containing at least one ASCII letter character will exhibit this behaviour.

Example, xn--bucher-kva decodes to bücher whereas XN--BUCHER-KVA decodes to BüCHER.

James

> -----Original Message-----
> From: idna-update-bounces at alvestrand.no [mailto:idna-update-
> bounces at alvestrand.no] On Behalf Of Vint Cerf
> Sent: Monday, 31 August 2009 6:28 AM
> To: Patrik Fältström
> Cc: Wil Tan; Andrew Sullivan; idna-update at alvestrand.no; John C Klensin
> Subject: Re: Comments on draft-ietf-idnabis-defs-10
> 
> you should not be able to reproduce this if I have understood the
> encoding/decoding algorithm. I thought it treated upper and lower case
> ascii as equal value for purposes of encoding and decoding.  this was
> to allow upper/lower case ascii to be case insensitive in the
> punycoding algorithm, I believe.
> 
> v
> 
> On Aug 30, 2009, at 3:54 PM, Patrik Fältström wrote:
> 
> > On 30 aug 2009, at 20.22, Wil Tan wrote:
> >
> >> However, if certain characters in an A-label have
> >> been uppercased, the Punycode decoding algorithm (due to its mixed-
> >> case
> >> annotation feature) may produce invalid U-label because the ASCII
> >> characters
> >> will be in capital letter form.
> >
> > Can you give examples of when this happens? I can not see this
> > result in the punycode algorithm. I also just did some tests with
> > mixed ascii, latin and chinese characters, and can not reproduce.
> >
> >   Patrik
> >
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