Re: [Mimi] Metadata Minimal MIMI (MIMIMI)

Hi Brendan,

Thanks for the feedback, I’ll address your points inline:

> At first glance, it seems this approach has the same efficiency as using encrypted handshake messages. That is, when I add a user to a group, I need to upload an encrypted blob whose size scales linearly with the number of members in the group. Is that right?

On the contrary, the proposal is to use public messages so that the DS can do what it would normally do without pseudonyms: Parse the public messages and keep a copy of the GroupInfo/ Public tree on the server to maximise efficiency. In other words, adding a new member to a groups only requires the sender to send a Commit and a Welcome. The invited member can then fetch the ratchet tree from the server. Conversely, when using External Commits, new joiners can fetch the ratchet tree from the server.

> I'm also concerned about the property that, if I'm ever added to even one group with a user, then I learn their connection key. Then I can use their connection key to de-anonymize them in any other group, regardless of whether I've been in that group or not.

It's a valid concern, just ending up in a group with another member shouldn’t give that member access to you beyond that group. That’s why connection keys must only be shared in 1:1 connections and not in other groups. Obviously the draft is not specific enough in that regard at this point. We need to flesh this out some more.

Raphael

> 
> On Fri, Apr 5, 2024 at 5:34 AM Konrad Kohbrok <konrad.kohbrok@datashrine.de <mailto:konrad.kohbrok@datashrine.de>> wrote:
>> Hi folks,
>> 
>> Raphael and I just uploaded an I-D with a proposal that sketches a pseudonym-based MIMI variant that aims to reduce MIMI’s metadata footprint. You can find it here: https://datatracker.ietf.org/doc/draft-kohbrok-mimi-metadata-minimalization/
>> 
>> We have been working on this approach for a while now and have already implemented and run a variant of what’s described in the I-D.
>> 
>> The I-D is quite high-level for now to make the concepts easier to grasp. If people are interested we can fill in gaps and add details in the next iterations.
>> 
>> Looking forward to continuing the discussion around metadata in the context of MIMI and any questions regarding our I-D!
>> 
>> Cheers,
>> Konrad
>> 
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