Re: [xmpp] message size

Alexander Holler <holler@ahsoftware.de> Sat, 08 March 2014 10:46 UTC

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Date: Sat, 08 Mar 2014 11:46:00 +0100
From: Alexander Holler <holler@ahsoftware.de>
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To: kevin@kismith.co.uk, Ashley Ward <ashley.ward@surevine.com>
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Cc: XMPP Working Group <xmpp@ietf.org>
Subject: Re: [xmpp] message size
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Am 06.03.2014 15:49, schrieb Kevin Smith:
> On Thu, Mar 6, 2014 at 2:44 PM, Ashley Ward <ashley.ward@surevine.com> wrote:
>> On 6 Mar 2014, at 14:40, Kevin Smith <kevin@kismith.co.uk> wrote:
>>> On Thu, Mar 6, 2014 at 2:35 PM, Ashley Ward <ashley.ward@surevine.com> wrote:
>>>> On 6 Mar 2014, at 14:28, Dave Cridland <dave@cridland.net> wrote:
>>>>
>>>>> You're saying to include, pre-encrypt, something like <spacer:junk xmlns:spacer='urn:...'>123465</spacer> in the plaintext order to defeat message size analysis of the ciphertext?
>>>>
>>>> It's XML - you could always just use <!-- --> comments or whitespace.
>>>
>>> Comments are slightly problematic, on account of being illegal.
>>
>> True - I often forget that XMPP isn't entirely XML compliant!
> 
> The stream isn't a real XML document (stream restarts break this) but
> not allowing comments doesn't stop it being XML, just a subset.

And just using whitespace is the most elegant solution. No necessary
changes and no obvious problems. So instead of

<message>foobar</message>

using

<message >foobar</message>

or e.g.

<message    >foobar</message      >

or something similiar is imho the most preferable way to add unused
plaintext.

Regards,

Alexander Holler