local part of e-mail addresses

[Werner Koch]

On Tue, 21 Jul 2015 13:24, neal at walfield.org said:

> introduces a potential for false positives.  However, I think it is
> extremely rare that email addresses like neal at walfield.org and
> Neal at walfield.org are distinct.  Thus, I think in this case,
> regularizing is the right approach.

I concur.  People actually tend to change capitalization of mail
addresses so that common MUA configurations ignore the case.

GnuPG's PKA system hashes the local-part but downcases all plain ASCII
characters first.  Characters with the MSB set are not touched and
hashed verbatim.  The reason for that the latter is that the rules for
changing the case of characters > 127 depend on the locale and are
sometimes not correctly implemented if at all well defined.  This is all
done on the UTF-8 encoding without any IDNA transformation.


Salam-Shalom,

   Werner


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