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Re: [openpgp] A way to securely define cleartext signature charset

2018-09-10 18:53:26


On Sep 10, 2018, at 11:23 AM, Neil Hunsperger 
<Neil_Hunsperger=40symantec(_dot_)com(_at_)dmarc(_dot_)ietf(_dot_)org> wrote:

I'll add a data point. Some years back, the PGP Desktop product added an 
unsigned "Charset" header to its ASCII armor. The result looked like this:

And for what it’s worth, section 6.2 of RFC 4880 says:

     - "Charset", a description of the character set that the plaintext
       is in.  Please note that OpenPGP defines text to be in UTF-8.  An
       implementation will get best results by translating into and out
       of UTF-8.  However, there are many instances where this is easier
       said than done.  Also, there are communities of users who have no
       need for UTF-8 because they are all happy with a character set
       like ISO Latin-5 or a Japanese character set.  In such instances,
       an implementation MAY override the UTF-8 default by using this
       header key.  An implementation MAY implement this key and any
       translations it cares to; an implementation MAY ignore it and
       assume all text is UTF-8.

All those MAYs are there because of the real world considerations. People still 
use JIS all over the place, for example, and this allows them to mark their 
text and have it work correctly. (That’s why we put it in both the standard and 
software. The examples of Latin-5 and JIS were real.) On the other hand, there 
was a completely reasonable objection that there are not only silly character 
sets that one could make up (nods to the computer language “Whitespace”), and 
real-world issues of what happens when the diehard Latin-5 people start sending 
messages to the diehard JIS people, and the resulting N^2 testing matrix.

Thus, this section lets an implementation throw its hands up in the air and 
scream wherever and whenever it wants, while giving a decent way to clearsign 
Japanese text.

        Jon

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