Re: [Json] secdir review of draft-ietf-jsonbis-rfc7159bis-03

John Cowan <cowan@ccil.org> Sat, 11 March 2017 02:09 UTC

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From: John Cowan <cowan@ccil.org>
Date: Fri, 10 Mar 2017 21:08:35 -0500
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To: Benjamin Kaduk <kaduk@mit.edu>
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Cc: Julian Reschke <julian.reschke@gmx.de>, draft-ietf-jsonbis-rfc7159bis.all@ietf.org, secdir@ietf.org, ietf@ietf.org, "json@ietf.org" <json@ietf.org>
Subject: Re: [Json] secdir review of draft-ietf-jsonbis-rfc7159bis-03
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On Thu, Mar 9, 2017 at 12:53 AM, Benjamin Kaduk <kaduk@mit.edu>; wrote:

If that's what's supposed to happen, it should probably be more
> clear, yes.  (But aren't there texts that have valid interpretations
> in multiple encodings?)
>

Not if the content is well-formed JSON and the only possible encodings are
UTF-8, UTF-16, and UTF-32.  It suffices to examine the first four bytes of
the input.  If there are no NUL bytes in the first four bytes, it is UTF-8;
if there are two NUL bytes, it is UTF-16; if there are three NUL bytes, it
is UTF-32.  This works because the grammar requires the first character to
be in the ASCII repertoire, and the NUL *character* (U+0000) is not allowed
at all.

-- 
John Cowan          http://vrici.lojban.org/~cowan        cowan@ccil.org
I don't know half of you half as well as I should like, and I like less
than half of you half as well as you deserve.  --Bilbo