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Re: [ietf-smtp] quoted-unprintable ?

2021-03-25 11:33:14
Ned Freed <ned(_dot_)freed(_at_)mrochek(_dot_)com> wrote:

The advantage of BINARYMIME over base64 is that base64 is 33% bigger
since it encodes six bits per octet rather than 8.  It occurs to me
that since everone these days supports 8BITMIME, one could invent a
quoted-unprintable encoding that encodes only the characters that are
special, CR LF NUL.  (To play it safe I'd also encode 0xff). This gets
you about a 2% size increase and stays compatible with 8BITMIME.

It's actually kind of tricky if you want to avoid pathological cases.
Combining the encoding with compression is the simplest way to avoid
that, since it's unlikely in the extreme that the compression scheme
will spit out a high percentage of any specific character.

Stuart Cheshire and Mary Baker have a super elegant binary escaping scheme
called "consistent overhead byte stuffing" (COBS) that has a guaranteed
overhead of less than 1%.

f.anthony.n.finch  <dot(_at_)dotat(_dot_)at>
Fisher, German Bight, Humber, Thames, Dover, Wight, Portland:
Southwest 4 to 6, occasionally 7 later. Slight or moderate, becoming
mainly moderate, occasionally rough later except in Dover and Thames.
Showers. Mainly good.

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