Re: [idn] Legacy charset conversion in draft-ietf-idn-idna-08.txt

["James Seng" <jseng@pobox.org.sg>]

- mapping to/from legacy encoding to ISO/IEC 10646 is available on the
CDROM, if you buy the CDROM version from your standard body.

- IDNA already specify (or suggested) that if the apps is using legacy
encodings, it should transcode to Unicode first.

-James Seng

> This last sentence seem to brush a practical problem under the rug.
> Most systems aren't Unicode based today, so in fact most systems will
> have to implement this unspecified transcoding.  The Unicode
> consortium has not specified how to transform Unicode to/from legacy
> encodings.  There are some unofficial mappings for ISO 8859-1 charsets
> on www.unicode.org/Public/MAPPINGS/, but even unofficial mappings for
> other charsets (in particular CJK) is not present.
>
> Real world scenario: My machine uses ISO-8859-1.  I enter 0xB5.  How
> is this transcoded into Unicode?  U+00B5 or U+03BC?  There are many
> similar examples.
>
> I think the third paragraph of the security consideration should more
> clearly express that IDNA actually is vulnerable to the attack if
> machines, like most machines on the Internet, use legacy encodings.
>
> Some high-level insight on the problem:
> http://www.cl.cam.ac.uk/~mgk25/unicode.html#conv
>
>
>