Re: [openpgp] Deprecating compression support

"Derek Atkins" <derek@ihtfp.com> Mon, 18 March 2019 13:32 UTC

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Date: Mon, 18 Mar 2019 09:31:55 -0400
From: "Derek Atkins" <derek@ihtfp.com>
To: "Neal H. Walfield" <neal@walfield.org>
Cc: "Justus Winter" <justuswinter@gmail.com>, openpgp@ietf.org
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Archived-At: <https://mailarchive.ietf.org/arch/msg/openpgp/54b5omdKzEgKzyoAJOanisnLw2Y>
Subject: Re: [openpgp] Deprecating compression support
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Hi,

On Mon, March 18, 2019 9:22 am, Neal H. Walfield wrote:
> Hi Justus,
>
> Thanks for bringing this up.
>
> On Mon, 18 Mar 2019 13:07:21 +0100,
> Justus Winter wrote:
>> I propose to deprecate compression support in OpenPGP.
>> ...
>> I realize that we cannot suddenly drop decompression support, but I
>> would suggest to stop emitting compressed data packets.  If this
>> proposal gathers traction, I would be happy to suggest a change to the
>> standard.
>
> I propose that we change the standard to say:
>
>   - Compliant implementations MUST NOT emit compressed data packets.

I would lessen this a tiny bit and say SHOULD NOT.  I can still imagine
cases where one MAY want to emit a compressed data packet, especially if
the sender and receiver have some out-of-band knowledge.

>   - For backwards compatibility, compliant implementations MAY
>     decompress compressed data packets.

I would also change this to SHOULD, because IMHO backwards compatibility
is important and there are decades of compressed data out there.

> Obviously, we should deprecate the "Preferred Compression Algorithms"
> subpacket as well.
>
> Note: removing compression support was one of the original goals:
>
>   Subject: [openpgp] details of 4880bis work
>   From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
>   Message-ID: <5527B621.3040104@cs.tcd.ie>
>   Date: Fri, 10 Apr 2015 12:38:09 +0100
>   Archived-At:
> <http://mailarchive.ietf.org/arch/msg/openpgp/ll36RGS81vXSXkVey0cR0zZ7WkI>
>
>   ...
>
>   g) remove compression entirely

I am not against removing it, but it should be deprecated first IMHO.

>   ...
>
> :) Neal

-derek

-- 
       Derek Atkins                 617-623-3745
       derek@ihtfp.com             www.ihtfp.com
       Computer and Internet Security Consultant