[messaging] pond alike lists (was: pond alike group messaging)

[azul]

Hi,

Mike Hearn:
> You're asking about encrypted/secure mailing lists, am I right?
Yes, exactly.

> Simplicity is always a good thing to aim for. How is a fancier solution
> with advanced crypto better than saying "The list moderator runs a tightly
> written web forum package via Tor".
I see your point. The forum is what we have right now. I think it could
actually be more simple.

For the admin:
Setting up a tor hidden service web forum is not trivial, registering a
new list could be. Currently you also need another channel to confirm
only the right people sign up or you need to distribute invitations
through a secure channel.

For the subscribers:
They have to remember the url, install tor-browser or use tails, create
a username and password and login regularly.
Instead i imagine a flow similar to establishing a contact with pond.
You would still have to install the software - but then you only type in
a shared secret and the name for the list and you're done.

On the server:
On the server the forum probably sits on top of some LAMP stack - lot's
of attack surface there. Far more than with pond right now. Sth. for
lists would probably be a bit more complex. But nothing compared to the
whole web stack we inherited.

On the client
You have a set of different webbrowsers (or only tor-browser if you're
lucky). Either way these are far more complex than a program that ONLY
does secure mailing lists and does it right.

So I hope the end result would be something more simple. Simple enough
to audit.
What seems complex right now is the task to build it. I totally agree
with that.

> This web forum would not have end to end encryption in the classical sense
> of course, but how does it differ in practice?
> 
>    - The list moderator sees all messages. But that's expected behaviour.
Your assumption is that list moderator = server owner. In a lot of real
world scenarios people use a few centralised list providers because it's
hard to setup servers securely. This would not matter as much if as
little information as possible was exposed to the server

>    - Anyone in the group sees all messages in the clear. But that's
>    expected behaviour.
Yes - but at the same time they leak a lot more information to someone
observing their internet connection. How often do they connect, when,
for how long, how much data do they transmit? With equally sized packets
and random breaks in between pond hides most of these details.

>    - If the server is seized, the taker can see all the messages. But if
>    the server *is run by* the list moderator, this is strictly equivalent
>    anyway: someone who wants to see all messages without being formally added
>    can just take the computer/credentials of anyone on the list.
Well - you can do a few more things when you compromise a forum... Log
the times people login, see what they actually read, try to deanonymize
them using browser bugs, alter the contents of the forums, etc.

> The primary advantages being you don't need to distribute software, there's
> no key distribution issues etc.
I think pond really solves the key distribution very nicely. I would
like to see a similar equivalent for mailing lists.
The software distribution also is an issue for anything that uses tor. I
think the tor-browser-launcher got a lot of things right. I would like
to see a pond-launcher. But in the long run i hope all of these tools
end up in the default install of linux distributions anyway.


Azul