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

[Jon Callas <[e-mail]>]

> On Sep 10, 2018, at 11:23 AM, Neil Hunsperger <Neil_Hunsperger=[e-mail]> 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