Re: Proposed XMPP Extension: End-to-End Encrypted Contacts Metadata

On 15 Jan 2026, at 10:52, Daniel Gultsch <[email protected]> wrote:
> 
> Hi,
> 
> On Thu, Jan 15, 2026 at 11:37 AM Daniel Gultsch <[email protected]> wrote:
> 
>> Title: End-to-End Encrypted Contacts Metadata
>> Abstract:
>> This specification describes how to encrypt contacts metadata to
>> minimize server exposure.
>> 
>> URL: https://xmpp.org/extensions/inbox/contacts-e2e.html
> 
> honestly I’m not entirely sure I like this. My naive implementation
> would just stick a bunch of <item xmlns='jabber:iq:roster'
> jid='[email protected]'/> in some sort of wrapper element into on
> singleton roster node. No multiple items, not separate node for
> groups. Just re-use the same <group/> children from jabber:iq:roster.
> I reckon for most medium sized rosters the encryption overhead is the
> bottle neck instead of the bandwidths constrains of one items vs
> multiple items.

For ’normal’ rosters, I think the many-items thing is an irritation rather than helpful. For a stpeter roster, though, you could start running into issues with size limits trying to put everything into a single item, I think? Of course, if you *do* have a multi-thousand item roster, one item per roster item is also unfortunate, so I suspect neither of these approaches is truly ideal.

On a different note - I’m curious why, in a spec that’s concerned with reducing metadata leakage, it’s requiring that you advertise to to world that you support this. I suspect the disco is both redundant and counterproductive :)

/K
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